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Guide to the installation of PV Systems 2nd Edition

1. DTI Pub URN 06 1972 Preface to 2nd edition 2006 Since the first edition 2002 the guide has been updated to reflect the significant experience gained with in the UK PV industry under the DTI solar PV grants programmes Other major changes covered include 1 Engineering Recommendation G83 1 2003 issued to replace ER 677 1 1 additional guidance for off grid battery systems 1 guidance for larger systems connected under ER G59 1 1 Part P Building Control notification Requirements ETSU Report No ETSU S P2 00355 REP 1 Authors BRE EA Technology Halcrow Group SunDog Energy 2nd Edition Sundog Energy Halcrow Group Energy Saving Trust Acknowledgments Thanks to the following for commenting on the drafts IEE HSE ESD Intersolar NAPS Systems NHBC Dulas CREST DTI Engineering Inspectorate EST Solarcentury Special thanks to Martin Cotterell First Published 2002 2nd Edition 2006 The work described in this report was carried out under contract as part of the DTI Sustainable Energy Programmes The views and judgements expressed in this report are those of the contractor and do not nec essarily reflect those of the DTI This guide was originally prepared by BRE and others on behalf of the DTI Every effort has been made to ensure that the information given herein is accurate but no legal responsibili ty can be accepted by the DTI BRE and their collaborators for any errors omissions or misleading statements Crown Copyr
2. For controllers with a separate battery sense function a fused battery sense cable can be installed 2 5 2 Battery over current protection A battery stores significant energy and has the capacity to deliver large fault currents Proper fault protection must be provided An over current device must be installed in all active non earthed conductors between the battery and the charge controller The over current device either a fuse or circuit breaker must e have a trip value as specified within the charge controller manual be rated for operation at d c at 12596 of the nominal battery voltage e have an interrupt rating greater than the potential battery short circuit current The length of cable between the over current device and battery terminal must be as short as practicable 2 5 3 Battery disconnection A means of manual isolation must be provided between the charge controller and the battery either combined with the over current device or as a separate unit The isolator must be double pole d c rated and load break and the length of the cable between it and the battery must be as short as practicable Isolation is to be installed and the system designed so that the PV array cannot directly feed the loads when the battery has been disconnected Combined fault protection and isolation Acircuit breaker provided for battery fault current protection may be used to provide isolation if it is rated as an isolat
3. 2 3 3 Inverters Inverters must carry a Type Test certificate to the requirements of SA Engineering Recommendation G83 1 or comply with all other parts of ER G83 1 unless specifically agreed by an engineer employed by or appointed by the DNO for this purpose and in writing Note A key safety consideration is that the PV system will disconnect when the distribution system is not energised This is to prevent the hazardous situation of the photovoltaic system feeding the network or local distribution system during a planned or unscheduled loss of mains Such an event is termed islanding and presents a potential danger to those working on the network distribution system Type Tests established through ER G83 1 ensure that an inverter is properly prevented from such islanding operation Other considerations addressed by ER G83 1 include the prevention of harmonics EMC compatibility and d c injection In order to simplify the earthing requirement an inverter with an isolating transformer is recommended see section 2 2 1 a This would protect against the possibility of a c exciting the d c side and remove the requirement to earth the array frame but does not override any need to connect the frame to earth for lightning protection purposes The inverter must be capable of withstanding the maximum array voltage and current as calculated in section 2 1 2 This must include any initial overvoltage period which is a featur
4. amp d c In Equipotential Zone Note freestanding ground mounted or building roof mounted arrays away from building metalwork will normally not be within the equipotential zone However a solar thermal system or other building linked metalwork installed within reach may extend the equipotential zone outside the normal building envelope Install amp bond to earth spike Bond direct to Consumer Note do not take PME out of Earthing Terminal equipotential Zone Note Use 10mm braid or equiv Note Use 10mm braid or equiv b Equipotential Zone is defined as a zone in which exposed conductive parts and extraneous conductive parts are maintained at substantially the same potential by bonding such that under fault conditions the differences in potential between simultaneously accessible exposed and extraneous conductive parts will not cause electric shock Extraneous conductive parts are conductive parts liable to introduce a potential generally earth potential and not forming part of the electrical installation such as a water pipe outside tap a metal downpipe anything conductive that is connected to Earth but not electrically part of the system c PME Protective Multiple Earthing an earthing arrangement whereby the supply neutral and earth are combined into a single conductor Where the incoming supply is PME the majority of domestic supply arrangements the PME earth cannot be take
5. PV Array d c Junction Box Danger contains live parts during daylight Do not disconnect d c plugs and sockets under load turn off a c supply first PV array d c isolator Danger contains live parts during daylight Inverter Isolate a c and d c before carrying out work PV system main a c isolator See Section 2 1 12 2 3 3 2 3 2 Do not work on this equipment until it is isolated from both mains and on site generation supplies Isolate on site generator at Isolate mains supply at 4 3 PV Installation Guide Appendix A 4 5 Operation amp maintenance manual The user manual should include as a minimum the following information System data e copy of the basic system information e A single line electrical schematic of the manuals and data sheets for the following system components m PV modules m Inverter m Other relevant product documentation Test results amp commissioning data of the test amp commissioning documentation see Appendix A B amp C e Table of inverter protection settings under over voltage under over frequency etc Operation amp maintenance data Procedures for verifying correct system operation A checklist of what to do in case of a system failure Shutdown isolation and startup procedures Maintenance amp cleaning recommendations if any Considerations for any future building works ad
6. i e overvoltage protection the junction or combiner boxes Connected to inverter serial No Array insulation Resistance Test voltage Ref IEC 60364 713 04 Pos Earth _ Equipment Required Test method Annex 1 Earth Insulation resistance test device Comments Insulation gloves Goggles Safety boots short circuit box if required Appendix C cont References Procedure 1 The test should be repeated for each Array as minimum It is also possible to test individual strings if required 2 Wear the safety shoes gloves and goggles 3 Where the test is to be undertaken between Earth and short circuited Array positive and Array negative cables short circuit the cables with an appropriate short circuit junction box 4 Connect one lead from the Insulation Resistance test device to the array cable s as per the NOTE above 5 Connect the other lead from the Insulation Resistance device to Earth as per NOTE above 6 Secure all the test leads eg with cable ties 7 Follow Insulation Resistance Test Device instructions to ensure the test voltage is according to table 1 and readings in M Ohms 8 Follow Insulation Resistance Test Device instructions to perform the test 9 Ensure system is de energised before removing test cables or touching any conductive parts Table 1 Test method System Voltage Test voltage Minimum Impedance V
7. a live system See requirements of Regulation 14 of Electricity at Work Regulations 1989 As current limiting devices PV module string circuits cannot rely on fuse protection for automatic disconnection of supply under fault conditions as the short circuit current is little more than the operating current Once established a fault may remain a hazard perhaps undetected for a considerable time Good wiring design and installation practice will serve to protect both the system installers and any persons subsequently coming into contact with the system from an electric shock hazard operator owner cleaner service engineers etc e Undetected fault currents can also develop into a fire hazard Without fuse protection to clear such faults protection from this fire hazard can be achieved only by both a good d c system design and a careful installation PV presents a unique combination of hazard due to risk of shock falling and simultaneous manual handling difficulty All of these hazards are encountered as a matter of course on a building site but rarely all at once While roofers may be accustomed to minimising risks of falling or injury due to manual handling problems they may not be used to dealing with the risk of electric shock Similarly electricians would be familiar with electric shock hazards but will not be used to handling large objects at heights Hazards associated with PV installation are outlined in th
8. and can get an electric shock to earth The electric shock voltage will increase with the number of series connected modules The use of insulated tools and gloves together with insulating matting to stand or sit on can mitigate this hazard PV Installation Guide Installation Sitework An electric shock may also be experienced due to the PV array developing a ground leakage path Good wiring practice double insulation and modules of Class Il construction can significantly reduce this problem but in any installed systems leakage paths may still occur Any person working on a PV system must be aware of this and take the necessary precautions 4 0 SYSTEM INSPECTION TESTING amp COMMISSIONING REQUIREMENTS DOCUMENTATION amp LABELLING 4 1 Inspection and testing Inspection and testing of the completed system to the requirements A 74 of BS 7671 must be carried out and documented Provision of this documentation is a requirement of Part P of the Building Regulations see section 2 4 2 The inspection and testing of a c circuits is comprehensively covered within BS 7671 and supporting technical guides Inspection and testing documentation typically comprises 3 forms an installation certificate which includes a schedule of items inspected and a schedule of test results The inspection and testing of d c circuits particularly testing PV array circuits requires special considerations Appendix C covers the inspection an
9. any installation being performed by a non PV specialist eg a PV array being installed by a roofer Plug and socket Y connectors can also be used to replace a junction box It is good practice to keep Y connectors in accessible locations and where possible note their location on layout drawings to ease troubleshooting in future PV Installation Guide Design Connectors must be d c rated Connectors must have the same or greater voltage and current ratings as the string d c main cable to which they are fitted A sign Do not disconnect d c plugs and sockets under load turn off a c supply first must be fixed next to connectors except those that are inaccessible to anyone except trained personnel in the course of PV maintenance or fault finding Connectors must not be used as the means for d c electrical switching see 2 1 12 as d c arcs can cause permanent damage to some connectors Note Plugs used in this application can be damaged by arc currents if disconnected under load While connectors are sometimes suggested as an alternative to specifying a d c rated switch such use is not permitted Connectors should be touch safe ie to a standard of ingress protection not less than IP 21 Class II and shrouded and be of a design totally dissimilar in appearance to any connectors used for the a c system 2 1 8 Other inline cable junctions In general cable junctions will be either by an approved p
10. are current limiting devices even under short circuit conditions the output current of a module will not rise above a certain level Isc Operating a module in short circuit is in general of little consequence indeed many charge controllers in battery charging systems routinely short circuit an array output For small systems the simplest approach is to ensure that the string cables are suitably rated such that they may safely carry the maximum possible fault current This method relies on oversizing the string cables such that the fault current can be safely accommodated Such a method does not clear the fault but simply prevents a fire risk from overloaded cables String fuses are required for systems of four or more strings see string fuse section for more information For a system with string fuses cables may be sized by applying the standard voltage and current multiplication tactors 2 1 6 Main d c Cable For a system of N parallel connected strings with each formed of M 4 74 series connected modules d c main cables must be rated as a minimum at Voltage X M x 1 15 Current lsc stc X N x 1 25 2 1 7 d c Plug and Socket Connectors PV specific plug and socket connectors are commonly fitted to module cables by the manufacturer Such connectors provide a secure durable and effective electrical contact They also simplify and increase the safety of installation works They are recommended in particular for
11. are shown below to help when reading this Guide They should not be used for a particular installation without taking into account the special circumstances of each individual installation pieoq uopnquisip U GOW 9104 c peas uoneljejsur Bugsa yun ur BOW eseud o uonoeoid 6GO BIA peroeuuog Ajddns Ss0 0E yijds suspenu sBuuis Ad ML wood jue d ur UOREJJEJSU Jun Aejdsip Addns DY wi T MAPS SR SRR AR ce REG BH w En fn vad p ul ajqeinoas p J0 EJOSI PE Sh So a as woos jued 4001 uo uonejjeysui uojoajoid dE fpi a EM mm e mm E ET zzz _ emn m jem 1 2 zzz mm mmm er em a a e m 2 m 4 _ ea NADA em mam UOBN S Ad Domestic a UOREJ EJSU o e asnoy Bunsix3 Aiddns ONG Aun FS HE UMI ELO yun jeuinsuo yun 1euinsuoo ui e noejoJd pejoeuuo
12. cover the possible increase in voltage current In addition some modules have an electrical output that is considerably higher during the first weeks of operation This increase is on top of that produced by temperature irradiance variation Typically operation during this period will take Voc Isc and nominal power output well above any value calculated using a standard multiplication factor To avoid oversizing for this eventuality the array could be left disconnected for that initial period Refer to the manufacturer for this information 2 1 3 PV Array Design Installations within the UK using currently available G83 1 type approved inverters typically operate with array voltages in the range of 120 to 500Vd c However it is to be noted that in some circumstances an array design can be implemented where the array is split into sub arrays with an open circuit voltage of less than 120 V PV Installation Guide Design Note The reason for reducing below 120 Vd c is that d c represents a different hazard to a c While an a c shock causes muscular spasms which may allow the person being shocked to retract or withdraw d c causes a continuous muscular contraction which may force the victim into contact for a longer period Risk data recommends reducing the potential shock level to below 120 if practicable Although a shock of 120 is unlikely to kill it could cause the victim to lose balance or concentr
13. during and after the installation phase The long term safety of the system can be achieved only by ensuring that the system and components are correctly designed and specified from the outset followed by correct installation operation and maintenance of the system Consideration of operation under both normal and fault conditions is essential in the design stage to ensure the required level of safety This aspect is covered in the DESIGN section of this guide PV Installation Guide Introduction It is then important to ensure that the long term safety of the system is not compromised by a poor installation or subsequent poor maintenance Much of this comes down to the quality of the installation and system inspection and testing regime This is covered in the INSTALLATION section of this guide Similarly much can be done during the planning and design stage to ensure that the installation is safe for the installers In some circumstances the application of the CDM regulations will be required Projects that employ fewer than five people on site and that last less than 30 days or involve fewer than 500 person days of work are exempt All key safety issues affecting the design and installation process are discussed in the guide The main safety issues are e The supply from PV modules cannot be switched off so special precautions should be made to ensure that live parts are either not accessible or cannot be touched during ins
14. of voltage and comprising all the conductors and other electrical and associated equipment used to conduct electricity for the purposes of conveying energy to one or more Customers installations street electrical fixtures or other Networks Islanding Any situation where a section of electricity Network containing generation becomes physically disconnected from the DNOs distribution Network or User s distribution Network and one or more generators maintains a supply of electrical energy to that isolated Network ROCs Renewable Obligation Certificates equivalent to 1MWh of PV generation PV Installation Guide Design 2 0 DESIGN 2 1 Design Part 1 d c System 2 1 1 PV Modules 2 1 1 1 Standard Modules Modules must comply with the international standards IEC 61215 in the case of crystalline types or IEC 61646 in the case of thin film types Modules must also carry a CE mark The use of Class II modules is generally recommended and strongly recommended for array open circuit voltages of greater than 120 V 2 1 1 2 Building integrated products modules These products should comply with IEC module requirements as above If no specific IEC Certificate is available eg for a one off bespoke product a statement and evidence from the manufacturer is required to prove general compliance In addition for integrated products where the PV forms part of the building envelope eg PV roof tiles proof of compliance
15. selection and sizing The selection of a battery is generally out of the scope of this document However some key considerations to be flagged are e is the battery fit for purpose i e appropriately rated for its duties In the majority of cases a true deep cycle battery will be required e does it have an adequate storage capacity and cycle life is a sealed or vented battery more appropriate for the particular installation e will the battery be made up of series cells or parallel banks While series cells will generally give better performance practical considerations may influence the design In general though banks with more than four parallel units are to be avoided The sizing of a battery is generally out of the scope of this document However for an effective charging regime where a PV array is the only charge source the battery would normally be sized so that the output of the PV array falls between the manufacturer s maximum and minimum recommended charge rates Charge discharge rates C are commonly expressed as an hourly rate derived from the formula Rate Capacity Ah Time h For example a C10 charge rate for a 500Ah battery would take place at 50A Charge rates between C5 and C20 are often used in systems with vented lead acid batteries for example 2 5 7 Battery installation labelling In an enclosed location ventilation must be provided to battery WA installations with an air inlet at low level and
16. string positive and negative parts Note While the installer will be handling live cables during the subsequent module installation because the circuit is broken at the d c switch disconnector there is no possibility of an electric shock current flowing from the partially completed PV string The maximum electric shock voltage that should ever be encountered is that of one individual PV module Where it is not possible to pre install a d c isolator eg a new build project where a PV array is installed prior to the plant room being completed cable ends connectors should be put temporarily into an isolation box and suitably labelled as per d c junction box section 2 1 9 Cables are to be well supported especially those cables exposed to the wind Cables must be routed in prescribed zones or within mechanical protection They must also be protected from sharp edges 3 3 3 Live working If it is unavoidable to work in any enclosure or situation featuring 64 simultaneously accessible live PV string positive and negative parts this must be performed either by utilising insulating gloves tools insulating materials for shrouding purposes and appropriate personal protective equipment see Regulations 4 4 14 and 15 of Electricity at Work Regulations 1989 HSE HSG 85 and BS EN 60903 and BS EN 60900 or by covering the PV array or by working at night with appropriate task lighting When covering PV panels during instal
17. to Note 2 in G83 1 For the connection of small embedded generators with a rating greater than 16A per phase the DNO may choose to use this Engineering Recommendation if it is considered to be more appropriate than G59 1 For example the connection of a 5kVA PV array or a 10kVA Wind Turbine This would however need to be agreed in advance and in writing with the DNO e Larger installations under G59 1 Written approval from DNO to be gained prior to works Commissioning in conjunction with DNO engineer or as required by DNO 1 5 Note on Layout This guide is split into two main parts the first detailing issues that need to be addressed during the design phase of a project and the second covering installation and sitework It is important to note however that many design issues covered in the first section may have a significant impact on the practical installation process covered in the second Throughout the guide the following format has been adopted to show the levels of authority for each guideline Bold text in blue against a shaded box with two ticks indicates mandatory and or broadly recognised requirements must Text in blue with one tick indicates recommended practice should Text marked as notes and in italics indicates explanatory material Introduction PV Installation Guide Commercial building b 1 6 Ready Reference to the Guide Example schematics for the two main types of system
18. to fault currents flowing though the d c system Two key problems need addressing overloaded string cables and significant module reverse currents both of which can present a considerable fire risk Fault analysis shows that the maximum fault current flowing in a string cable to be N 1 x Isc A system of three or fewer strings cannot generate sufficient fault currents to present hazardous module reverse currents Hence with three or fewer strings fuses can be omitted providing that string cables are suitably rated Such a method does not clear the fault but simply prevents a fire risk from overloaded cables The installation of string fuses can provide protection against fault currents in all other cases While some fault combinations are less likely than others in order to provide full protection of all cables and modules string fuses are required in both the positive and negative legs of the string cabling See section 2 1 5 Note As in section 2 1 9 it is required that some suitable means of electrical isolation be provided This will also enable engineers to separate out individual strings for testing and tracing faults A system fitted with suitable removable string fuses provides an ideal way to accomplish this Thus while it may not be necessary to fit string fuses on an array formed from two or three strings their use may still be beneficial 2 1 11 Blocking Diodes Blocking diodes are not commonly used in a grid conne
19. tonii MENINOOKL TTENN The SSEG installation complies with the relevant sections of Engineering Signature Date Name BLOCK LETTERS FOR CONSTRUCTION Recommendation G83 1 being the person s responsible tor the construction of the electrical installation as indicated by mylour signatures below particutars of which are de scribed above having exercised reasonable sk l and care when carrying out the construction hereby CERTIFY that the construction work for which liwe have been responsible is to the best of my our knowledge and bebet in accordance with BS 7071 amended to dato except for the departure if any detailed as foliows Protection settings have been set to comply with Engineering a The protection settings are protected from alteraton except by prior written The extent of liability of the signatory is limited to the work described above as the subject of this Cerificate agreement between the DNO and the Customer or his agent For CONSTRUCTION of the instafason Signature Safety labels have been fitted in accordance with section 6 1 of Engineering Name BLOCK LETTERS FOR INSPECTION amp TESTING Recommendation G83 1 We beng the person s responsible for the inspection amp testing of the electrical installation as indicated by 4 sv rei ate Ta prod rasan wl and caro wen Cary eu e wget ei ay CER IFY that the work for which Uwe have been responsible is to the best of my our knowledge and
20. uo UOREJ EJSU Bi Ad S Buis TA 2 BUIS Ad wajsAs 2 uonej ejsul 2 e uonisod Jjo ur aqeinoas elod ejqnop 10JEJOSI uie i Yo uonelejsul 2048105 oo pauuoosp PV Installation Guide Design 1 7 List of Terms PV cell basic PV device which can generate electricity when exposed to light such as solar radiation PV module smallest completely environmentally protected assembly of interconnected PV cells PV string circuit in which PV modules are connected in series in order for a PV array to generate the required output voltage PV array mechanically and electrically integrated assembly of PV modules and other necessary components to form a d c power supply unit PV array junction box enclosure where all PV strings of any PV array are electrically connected and where protection devices can be located if necessary PV generator assembly of PV arrays PV generator junction box enclosure where all PV arrays are electrically connected and where protection devices can be located if necessary PV grid connected system a PV generator operating in parallel with the existing electricity network PV string cable cable connecting PV modules to form a PV string PV string fuse a fuse for an individual PV stri
21. where electricity supplies are usually by long overhead lines Surges may be induced on both the PV array conductors or the a c cables leading to the building 2 2 4 1 Lightning Protection Systems Where there is a perceived increase in risk of direct strike as a consequence of the installation of the PV system specialists in lightning protection should be consulted with a view to installing a separate lightning protection system in accordance with BS 6651 Note It is generally accepted that the installation of a typical roof mounted PV system presents a very small increased risk of a direct lightning strike However this may not necessarily be the case where the PV system is particularly large where the PV system is installed on the top of a tall building where the PV system becomes the tallest structure in the vicinity or where the PV system is installed in an open area such as a field If the building or dwelling is fitted with a lightning protection system LPS a lightning protection installer should be consulted as to whether in this particular case the array frame should be connected to the LPS and what size conductor should be used Note In some cases it may be possible to forgo bonding to the LPS if the array frame is sufficiently far away from it A system for determining whether it is necessary can be found in BS 6651 Code of Practice for Protection of Structures against Lightning Alternatively consult the inst
22. CDM Regulations with regard to the design installation operation maintenance decommissioning and disposal of PV installations in buildings It also provides a commentary on the UK legislative framework with particular reference to CDM Regulations hazards and risks associated with PV installations and PV issues that must be addressed in the Health and Safety Plan and Health and Safety File i Draft IEC 62446 Ed 1 Grid connected PV systems Minimum system documentation commissioning tests and inspection requirements Note This standard will define the minimum information and documentation required to be handed over to a customer following the installation of a grid connected PV system This document also describes the minimum commissioning tests inspection criteria and documentation expected to verify the safe installation and correct operation of the system This document is not written for AC module systems or systems that utilize energy storage e g batteries or hybrid systems 1 Guide CE72 Installing small wind powered electricity generating systems Energy Efficiency Best Practice in Housing 2004 Note A companion Guide for small wind systems 500W to 25kW 1 Draft IEC 62257 7 2 Technical Specification Recommendations for small renewable energy and hybrid systems for rural electrification Part 7 1 Generators Photovoltaic arrays Note This is a draft Technical Specification not a Standard but includes much use
23. G83 1 The scope has been extended in this 2nd edition to provide some guidance on larger systems and off grid battery installations Mechanical design of the PV array is not within the scope of this document BRE digest 489 Wind loads on roof based Photovoltaic systems and BRE Digest 495 Mechanical Installation of roof mounted Photovoltaic systems give guidance in this area 1 2 Standards and Regulations Any PV system must comply with Health and Safety Requirements BS 7671 and other relevant standards and Codes of Practice Much of the content of this guide is drawn from such requirements While many UK standards apply in general terms at the time of writing there is still relatively little which specifically relates to a PV installation However there are two documents which specifically relate to the installation of these systems that are of particular relevance e Engineering Recommendation G83 1 2003 Recommendations for the connection of small scale embedded generators up to 16A per phase in parallel with public low voltage distribution networks e Guidance Note 7 to BS 7671 Special Locations Section 12 Solar Photovoltaic PV Power Supply Systems ISBN 0 85296 995 3 2003 1 3 Safety From the outset the designer and installer of a PV system must consider the potential hazards carefully and systematically devise methods to minimise the risks This will include both mitigating potential hazards present
24. allers of the LPS Where an LPS is fitted PV system components should be mounted away from lightning rods and down leads see BS 6651 For example an inverter should not be mounted on an inside wall that has a down lead running just the other side of the brickwork on the outside of the building 2 2 4 2 Surge Protection measures All d c cables should be installed to provide as short runs as possible and positive and negative cables of the same string or main d c supply should be bundled together avoiding the creation of loops in the system This requirement for short runs and bundling includes any associated earth bonding conductors Long cables eg PV main d c cables over about 50 m should be installed in earthed metal conduit or trunking or be screened cables such as mineral insulated or armoured Note These measures will act to both shield the cables from inductive surges and by increasing inductance attenuate surge transmission Be aware of the need to allow any water or condensation that may accumulate in the conduit or trunking to escape through properly designed and installed vents Most grid connect inverters have some form of in built surge suppression however discrete devices may also be specified Note To protect the a c system surge suppression devices may be fitted at the main incoming point of a c supply at the consumer s cut out To protect the d c system surge suppression devices can be fitted at th
25. an outlet at the highest point in the room or enclosure Sufficient ventilation is needed to remove battery gases It is particularly important in the case of vented lead acid units as hydrogen is given off during charging and a concentration of more than 4 creates an explosion hazard Ventilation also prevents excessive heat build up BS 6133 Safe operation of lead acid stationary batteries gives a procedure for calculating ventilation requirements Battery banks must be housed in such a way that BS 6133 e access can be restricted to authorised personnel e adequate containment is assured e appropriate temperature control can be maintained Battery terminals are to be guarded so that accidental contact with persons or objects is prevented The ideal operating temperature for a lead acid battery is around 25 C temperatures significantly above or below this will lead to reduced lifetime and capacity Indeed at very low temperatures discharged batteries may freeze and burst at high temperatures thermal runaway can occur in sealed batteries Items which could produce sparks e g manual disconnects relays should not be positioned within a battery box or directly above one Battery gases are corrosive so cables and other items inside a battery enclosure need to be corrosion resistant Sensitive electronic devices should not be mounted in or above a battery box To ensure proper load charge sharing in a battery bank made
26. artment before starting the work The contractor registers under a Competent Person Scheme as approved by the office of the deputy prime minister Note An electronic version of the form is available at the Local Authority Building Control website www link2content co uk uploads buildingnotice 202005 20unprotected 1 doc and it can be submitted using their Submit a Plan scheme www labc services co uk buildingregs default asp e Engineering Recommendation G83 1 Sept 2003 Recommendations for the connection of Small scale Embedded Generators up to 16A per phase in parallel with Public Low Voltage Distribution Networks Energy Networks Association 2003 www energynetworks org dg01 asp Note This simplified connection route applies to type tested inverters for systems up to about 5kVA per phase see sect 2 4 1 Prior notification of the Distribution Network Operator DNO is not required for single installations but is required for multiple single phase installations It refers to the Electricity Safety Quality and Continuity Regulations ESQCR 2002 Draft prEN 50438 Requirements for the connection of micro cogenerators in parallel with public low voltage distribution networks is a European version which once issued will also cover systems up to 16A e Engineering Recommendation G59 1 Recommendations for the connection of Embedded Generating Plant to the Regional Electricity Compa
27. ation and so expose them to another risk e g losing balance when working on a roof Double insulation insulation comprising both basic amp supplementary insulation International Electrotechnical Vocabulary IEV 195 06 08 appropriate barriers and separation of parts must be applied to all systems with an open circuit voltage of gt 120 Vd c Class Il insulation on the d c part of the PV system even if less than 120 Vd c is strongly recommended Note Double insulation of the d c circuit d c wiring connectors etc greatly minimises the risk of creating accidental shock current paths eg via damaged cable coming in contact with PV frame and the risk of fire Having a PV junction box with negative and positive parts well separated and protected by barriers or better still by utilising separate enclosures significantly reduces the potential shock risk to the installer Note Though commonly used for the main d c cable e g for long d c cable runs in exposed locations such as on flat roofs or where cable is buried sheathed and armoured cable with two or more singly insulated cores does not constitute double insulated cable though in this application it is acceptable as it affords a good degree of fault risk reduction see 2 1 4 2C 2 1 4 d c Cables General 2 1 4 1 Cable sizing Cables must be rated as a minimum to the voltage and current ratings derived using the multiplication factors in 2 1 2 Standard de ra
28. be rated for operation at x M x 1 15 e The string fuse must have a tripping current which is less than 2 x Isc stc and the string cable current carrying capability whichever is the lower value Note The requirement for omitting string fuses in arrays with three or fewer series connected strings is valid for the majority of silicon crystalline conventional modules However when applying this rule a system designer must verify with the manufacturer that the module is capable of withstanding a reverse current of 2 x 1 15 x Isc w w PV Installation Guide Design For some modules the reverse current rating provided by the manufacturer may permit more than three parallel connected strings to be installed without string fuses In such cases the number of strings that may be connected in parallel without the use of fuses is calculated by ensuring Ir gt I ste x N 1 x 1 25 where Ir is the maximum permitted reverse current quoted by the module manufacturer The use of fuses or MCBs miniature circuit breakers is permissible provided they meet the above criteria and are rated for use in an inductive circuit and will operate for currents flowing in either direction through the device For a system of three or fewer strings with NO string fuses string cables must have a minimum current rating of Isc stc x N 1 x 1 25 Note In a PV array formed from a number of strings fault conditions can give rise
29. belief in accordance with date except for the if ary detailed as follows The SSEG installation complies with the relevant sections of BS 7671 and an gt Comments continue on seperate sheet if necessary The extent of liability of the signatory is limited to the work described above as the subject of this Cerificate For INSPECTION AND TEST of the instalabon Signature Name BLOCK LETTERS Name Signature Date Pagelof note 5 Appendix B cont Appendix B cont PARTICULARS OF SIGNATORIES TO THE ELECTRICAL INSTALLATION CERTIFICATE note of supply to be detaded on attached schedules PARTICULARS OF INSTALLATION REFERRED TO IN THE CERTIFICATE 79 ree se m wora Means of Earthing Distributors tacy C Maximum demand load Details of installation Earth Electrode where applicable Instaliation Type Electrode resistance 10 earth ne rodis tape etc vee C58 To incoming water and or gas service other elements Main Switch or Circuit breaker No of poles Current rating AURI erret qoem ementi top Fuse rating or setting Rated residual operating current lan MA and operating time of ms at lpn ory mhara on RCD m maie are und an 4 min ras COMMENTS ON EXISTING INSTALLATION I f ces c a sera o wasters sey Saanen 763 SCHEDULES note 2 The attached Schedules are part of this document and
30. ct system as their function is better served by the installation of a string fuse Historically they were specified to prevent any reverse current flowing through parallel connected strings much as a string fuse is intended to do However e the installation of a blocking diode results in a small voltage drop across the diode e blocking diodes may fail as a short circuit and therefore require regular testing Specification of string fuses can provide sufficient reverse current protection without the problems and power losses associated with a blocking diode If specified a blocking diode must have as a minimum a reverse voltage rating of 2 x Voc x number of modules in the string stc 2 1 12 d c Switch The d c switch provides a means of manually electrically isolating the entire PV array Such electrical isolation is required during system installation and subsequent system maintenance or repair work It should be located adjacent to or integrated into the inverter An additional d c switch may be specified for systems with long d c cable runs typically at the point of cable entry into the building so as to provide a means of isolating the cable for safety reasons or maintenance works e The d c switch must be double pole to effectively electrically isolate both PV array positive and PV array negative e The d c switch must be rated for d c operation Note Switching a c is less demanding than switching d c wit
31. d testing of PV array circuits and documentation to be provided 4 2 Array commissioning tests PV array string performance tests are recommended to verify performance as a check for faulty modules These will entail additional tests over and above those set out in BS 7671 and the associated guidance This may require a means of measuring solar radiation for larger installations if radiation levels are changing during testing Simultaneous monitoring of the solar radiation can present practical difficulties unless the system has a radiation sensor installed and its cable is accessible at the place where testing is carried out If radiation conditions are reasonably constant ie no sudden obscuring of direct sunlight by clouds comparing one open circuit string voltage with another will identify faulty strings Guidance on commissioning tests can also be found in appendix C 4 3 E R G83 1 and G59 1 commissioning As noted in section 2 4 1 in order to satisfy the requirements of the distribution Network Operator various tests and documentation needs to be provided See section 1 4 and 2 4 1 for more details on the process to be followed depending on the size of system Compliance with DNO requirements will include w w PV Installation Guide Installation Sitework e Inverters should be programmed such that the automatic protection system operates at m Operating voltage greater than 264 V phase to neutral m Opera
32. ditions Transmission of lightning induced surges Electromagnetic interference Two types of connection to earth need consideration a Earthing of exposed conductive parts eg the array frame b System earths where an array output cable is connected to earth The earthing arrangements recommended in this guide are based upon those given in BS 7430 BS 6651 and BS 7671 2 2 1 Earthing of exposed conductive parts array frame The majority of installations will utilise class Il modules class Il d c cables amp connectors and be connected to the mains via an inverter with an isolation transformer This approach is recommended and permits the array frame to be left floating Notes to terms used in diagram a Isolating transformer An isolating transformer is one in which the input and output windings are electrically separated by double or reinforced insulation see BS 3535 While the hazards presented by an array frame reaching the system d c potential may be significant the potential fault shock current is typically much less than that from a mains fault Hence it is the electrical separation of the mains from the d c using an isolating transformer that is the key determining factor when assessing the requirement for array frame earthing Array Frame Earthing Decision Tree Class 11 modules and Class Il Cables connectors ions amp Junction Boxes and Isolation Transformer in Inverter Note to BS 3535 between a c
33. durable Circuit Description Method of protection against indirect contact Equipment vulnerable to testing Description of Work Deviations from Wiring Regulations and special notes See notes on schedule of test results E Appendix C cont Appendix C cont Part 2 PV system commissioning test sheets Sheet 2 array test Field insulation test procedure as in draft IEC PV Array Test Report d c circuits Safety Report reference No Contractors name and address Read and make sure you understand this procedure before you start any work Insulation testing is an electric shock hazard use caution when performing the testing nstalllation address NM Do not perform the test before you have received practical training Limit the access to the working area Do not touch and take measures to prevent any other persons to touch any metallic surface lest date Signature with any part of your body when performing the insulation test Do not touch and take measures to prevent any other persons to touch the back of the Description of work under test Test instrument s module laminate or the module laminate terminals with any part of your body when performing the insulation test Whenever the Insulation test device is energised there is voltage on the testing area The equipment is to have to hav
34. e inverter end of the d c cabling and at the array To protect specific equipment surge suppression devices may be fitted as close as is practical to the device w PV Installation Guide Design 2 3 Design Part 3 a c System 2 3 1 a c Cabling An inverter supplied from a PV array must preferably be installed in a dedicated circuit in which nocurrent using equipment is connected and no provision is made for the connection of current using equipment and e no socket outlets are permitted An inverter must not be connected by means of a plug with contacts which may be live when exposed Where an electrical installation includes a PV power supply system without at least simple separation between the a c side and the d c side an RCD installed to provide fault protection by automatic disconnection of supply must be type B RCD according to BS EN 60898 IEC 60755 amendment 2 a c cables are to be specified and installed in accordance with BS 7671 The a c cable connecting the inverter s to the consumer unit should be oversized to minimise voltage drop A 196 drop or less is recommended However in larger installations this may not be practicable or economic due to the very large size of cable resulting In this case the designer should minimise voltage drop as far as possible and must remain within voltage drop limits as prescribed by BS 7671 Note When generating the voltage at the inverter
35. e DTI s free manual Photovoltaics in Buildings Safety and the CDM Regulations PV Installation Guide Installation Sitework 3 3 d c Circuits installation 3 3 1 Personnel All persons working on the live d c cabling of a Photovoltaic PV system must be experienced trained in working with such systems and fully acquainted with the voltages present on that system in particular Plug and socket connectors simplify and increase the safety of installation works see section 2 1 7 They are recommended in particular for any installation being performed by non PV specialist eg a PV array being installed by a roofer 3 3 2 Sequence of works All d c wiring should if possible be completed prior to installing a PV array This will allow effective electrical isolation of the d c system via the d c switch disconnector and PV module cable connectors while the array is installed and effective electrical isolation of the PV array while the inverter is installed Typically this would require an installation of d c switch disconnector and d c junction box es e String array positive and negative cables from the d c disconnect junction box to either end of the PV string array e PV array main cables from d c switch to inverter This should be carried out in such a way that it should never be necessary for an installer to work in any enclosure or situation featuring simultaneously accessible live PV
36. e automatic auto discharge capability String 1 2 3 4 n Array Module NOTE REGARDING TEST METHOD Quantity Two test methods are possible Array parameters Vocisto a Test between Array Negative and Earth followed by a test between Array Positive and Earth b Test between Earth and short circuited Array Positive amp Negative Protective Device Type Where the structure frame is bonded to earth the earth connection may be to any suitable Rating A earth connection or to the array frame where the array frame is utilised ensure a good d c Rating V contact and that there is continuity over the whole metallic frame Capacity kA For systems where the array frame is not bonded to earth eg where there is a class m installation a commissioning engineer may choose to do two tests i between Array cables Wiring Type gt and Earth and an additional test ii between Array cables and Frame Phase mm Earth ay For Arrays that have no accessible conductive parts eg PV roof tiles the test should be between Array cables and Building Earth String test Test method Annex 2 Voc V Test Zone Preparation Isc A Sun 1 Limit access to non authorized personnel Polarity check 2 Isolate the PV array from the inverter typically at the array switch disconnector Earth continuity where fitted 3 Disconnect any piece of equipment that could have impact on the insulation measurement R
37. e of some module types Note It is common practice for an inverter array power ratio to be less than unity see section 2 6 1 but it is important to ensure that the inverter cannot be damaged by array peak output This is particularly the case with some thin film PVs that have an initial overvoltage period See also notes regarding inverter mpp operating range in section 2 6 1 PV Installation Guide Design It is recommended that Inverters carry a sign Inverter isolate a c and d c before carrying out work 2 3 4 a c Fault Current Protection Short circuit protection for the dedicated feeder cable from the inverter s must be provided at the consumer unit This electrical protection is to be specified and installed in accordance with the requirements of BS 7671 Note Short circuit protection is not required at the inverter output If using an RCD for a c side earth fault protection see section 2 3 1 2 3 5 Metering Inverter output meter As a minimum metering at the inverter output should be installed to display record energy delivered by the PV system kWh In addition it is highly recommended for instantaneous power output kW to be displayed This will not only add to customer satisfaction it should lead to more effective fault detection A kWh meter approved by OFGEM is recommended as it may facilitate payment on ROCs and other Electricity company scheme payments as they become available The meter s
38. e part of a PV installation from a PV cell to the d c terminals of the PV inverter a c side part of a PV installation from the a c terminals of the PV inverter to the point of connection of the PV supply cable to the electrical installation Simple separation separation provided between circuits or between a circuit and earth by means of basic insulation Inverter Isolating Transformer where the input amp output windings are electrically separated by double or reinforced insulation Isolation A function intended to cut off for reasons of safety the supply from all or a discrete section of the installation by separating the installation or section from every source of electrical energy Isolator Disconnector A mechanical switching device which in the open position complies with the requirements specified for isolation An isolator is otherwise known as a disconnector A disconnector is otherwise known as an isolator Equipotential Zone where exposed conductive parts and extraneous conductive parts are maintained at substantially the same voltage potential PME Protective Multiple Earthing where the supply neutral and earth are combined into a single conductor Distribution Network Operator DNO The organisation that owns or operates a Distribution Network and is responsible for confirming requirements for the connection of generating units to that Network Electricity Network An electrical system supplied by one or more sources
39. e voltage and current requirements of the d c system the maximum values that could occur need to be assessed The maximum values originate from two PV module ratings the open circuit voltage Voc and the short circuit current Isc which are obtained from the module manufacturer The values of Voc and Isc provided by the module manufacturer are those at standard test conditions stc irradiance of 1000 W m air mass 1 5 and cell temperature of 25 C Operation of a module outside of standard test conditions can considerably affect the values of Voc stc Isc stc In the field irradiance and particularly temperature can vary considerably from stc values The above multiplication factors allow for the maximum values that may be experienced under UK conditions All other module types All d c components must be rated as a minimum from a Specific calculations of worst case Voc and Isc calculated from manufacturer s data for a temperature range of 15 C to 80 C and irradiance up to 1250 W m2 b A calculation of any increase in Voc or Isc over the initial period of operation This increase is to be applied in addition to that calculated above Note Some types of PV modules have temperature coefficients considerably different to those of standard mono and multi crystalline modules The effects of increased irradiance may also be more pronounced In such cases the multiplication factors used for crystalline silicon modules may not
40. ening an enclosure is fully aware of this A readily accessible disconnection device shall be provided to isolate individual strings Isolation shall be provided in both positive and negative string cables Note String isolation shall be achieved by any suitable means such as appropriately located plug and socket connectors or removable string fuses Any such isolation should not be carried out with the system under load The short circuit protection afforded by the cable installation throughout the rest of the d c circuit needs to be maintained in the construction and makeup of the d c junction box See IEC 60536 and IEC 61140 It is recommended that short circuit protection shall be achieved by e Fabrication of the enclosure from non conductive material e Positive and negative busbars adequately separated and segregated within the enclosure and or by a suitably sized insulating plate or separate positive and negative junction boxes e Cable and terminal layout such that short circuits during installation and subsequent maintenance are extremely unlikely 2 1 10 String Fuses For a system of N parallel connected strings with each formed of M series connected modules String fuses must be provided for all arrays formed of four or more strings Fuses must be fitted in both positive and negative string cables for all strings e The string fuse must be rated for d c operation at the fault energies present e The string fuse must
41. entification may be omitted Binding and sleeves for identification purposes shall comply with BS 3858 as appropriate 2 1 5 String Cables A string is a circuit in which PV modules are connected in series in order for a PV array to generate the required output voltage String Cables String Cables N Strings connected in parallel Main d c Cable M modules per string connected in series For a system of N parallel connected strings with each formed of M series connected modules string cables are to be rated as follows WV a Array with no string fuses of three or fewer strings only Voltage X M x 1 15 Current Isc stc X N 1 1 25 b Array with string fuses Voltage Vocst X M x 1 15 Current lc X 1 25 The sizing process for string cables in arrays with three or fewer series connected strings is valid for the majority of silicon crystalline conventional modules However when applying this rule a system designer must verify with the manufacturer that the individual modules are capable of withstanding a reverse current of 2 x 1 15 x Isc See section 2 1 10 for further information Note PV module string circuits cannot rely on conventional fuse protection for automatic disconnection of supply under tault conditions This is because the short circuit current is little more than the operating current a fuse would simply not operate A photovoltaic cell acts as a current source hence PV modules
42. ful guidance and explanation of international best practice for installation of PV systems 1 BS 6133 1995 Code of practice for Safe operation of lead acid stationary batteries Note This includes guidance on design operation amp maintenance of battery systems i BSI PD 6484 1979 Commentary on corrosion at bimetallic contacts and its alleviation Note This includes guidance on the selection of metals for mechanical design of arrays 1 BS 476 Fire tests on building materials and structures 1 BS 6399 Loading for buildings Code of practice 1 BS 5534 Code of practice for slating and tiling including shingles i BS 3535 Specification for safety isolating transformers for industrial and domestic purposes 1 BS 60947 Specification for low voltage switchgear and controlgear 1 BS3858 Specification for binding and identification sleeves for use on electric cables and wires i PD 6484 Commentary on corrosion at bimetallic contacts and its alleviation Note Information on the current Government s Grant scheme Low Carbon Buildings Programme can be found on the Energy Saving Trust website www est org uk DTI Sustainable Energy Programmes Do not work on this equipment until it is isolated from both mains and on site generation supplies Isolate on site generator at Isolate mains supply at Sample Dual Supply Label G83 1
43. h an a c supply the voltage passes through O V many times a second A switch must be rated to break d c an equivalent a c rated switch is not acceptable or safe e The d c switch should be load break rated the use of non load break switches is not recommended e The d c switch must be rated for the system voltage and current maxima as calculated in section 2 1 2 e The d c switch or switches must be labelled as PV array d c isolator with the ON and OFF positions clearly marked Switch enclosures must also be labelled with Danger contains live parts during daylight All labels must be clear easily visible constructed and affixed to last and remain legible for as long as the enclosure w w w PV Installation Guide Design Note A PV array is unusual in that it cannot be turned off terminals will remain live at all times during daylight hours It is important to ensure that anyone opening an enclosure is fully aware of this An MCB may be used as a d c switching device provided it meets all the above requirements The use of an MCB will provide protection against overcurrent and so the MCB rating must be carefully chosen so as not to operate falsely for switching surges and transients 2 2 Design Part 2 Earthing and Lightning Protection Connection of parts of a PV system to earth affects The electric shock risk to people in the vicinity of the installation The risk of fire under fault con
44. hould be located where the consumer can readily observe it Building Export meter Although not directly part of the PV system in order to enable payment on exported electricity a kWh export meter approved by OFGEM with appropriate meter reading may be required The appropriate Electricity Supplier should be contacted to find out any particular requirements and to arrange for its fitting 2 4 Design Part 4 Design Approval 2 4 1 DNO approval A mains connected PV installation generates electricity synchronised with the electricity supply Installers are obliged to liase with the relevant distribution Network Operator DNO in the following manner e Single installation covered by G83 1 notification at or before day of commissioning followed by G83 1 paperwork G83 1 appendix 3 within 30 days e Multiple installation covered by G83 1 application to proceed G83 1 appendix 2 On commissioning notification and appendix 3 as above Note For single installations of slightly greater than 16A attention is drawn to Note 2 in G83 1 For the connection of small embedded generators with a rating greater than 16A per phase the DNO may choose to use this Engineering Recommendation if it is considered to be more appropriate than G59 1 For example the connection of a 5kVA PV array or a 10kVA Wind Turbine This would however need to be agreed in advance and in writing with the DNO e Larger installations under G59 1 Written appro
45. ight 2006 Contents 1 0 INTRODUCTION 1 1 Scope 1 2 Standards and regulations 13 Safety 14 Parallel generation 15 Note on layout 1 6 Ready reference to the guide 17 List of terms 2 0 DESIGN 2 1 Design part 1 d c system 2 1 1 PV modules 2 1 1 1 Standard modules 2 1 1 2 Building integrated products modules 2 1 2 system minimum voltage and current ratings 2 1 3 PV array design 2 14 d c cables general 214 1 Cable sizing 2 1 4 2 Cable type and installation method 2 1 5 String cables 2 1 6 Main d c cable 2 1 7 d c plug and socket connectors 2 1 8 Other inline cable junctions 2 19 d c Junction box 2 1 10 String fuses 2 1 11 Blocking diodes 2112 d c switch 2 2 Design part 2 earthing and lightning protection 2 21 Earthing of exposed conductive parts array frame 2 22 System earthing d c conductor earthing 2 23 Inverter earthing 2 24 Lightning and surge protection 2 2 5 Lightning protection systems 2 2 6 Surge protection measures 23 Design part 3 a c system 2 31 ac cabling 2 3 2 a c switch disconnector 2 3 3 Inverters 2 34 fault current protection 2 3 5 Metering N O Ui Ui ur Ul 10 10 10 10 10 10 11 12 12 12 13 15 15 16 16 17 18 19 20 20 22 22 22 22 23 24 24 25 25 26 26 Contents Introduction 2 4 Design part 4 design approval 2 4 1 DNO approval 2 4 2 Planning permission 2 4 3 Building Regulations part P electrical safe
46. ion device A fuse assembly provided for fault current protection may be used to provide isolation if it has readily removable fuses eg fuse unit with disconnect mechanism w w PV Installation Guide Design 2 5 4 Cables in battery systems The requirements set out in the main sections of this guide apply Note In some circumstances a voltage drop greater than that in section 2 1 4 1 may be justified on economic grounds In addition All cables must have a current rating above that of the relevant over current device nearest downstream fuse circuit breaker Cable current ratings are to be adjusted using standard correction factors for installation method temperature grouping and frequency to BS 7671 2 5 5 PV String cable and fuse ratings String cables upstream of the charge controller must be rated to the trip current of the nearest downstream device plus the rating as calculated in section 2 1 5 A PV battery system must be designed such that the string cable string fuse design and specification reflects that fault currents may come either from the array itself from the battery or from both Again cable current ratings are to be adjusted using standard correction factors for installation method temperature grouping and frequency to BS 7671 Note Specification amp labelling for the PV cables junction boxes connectors etc should be as in the main sections of the guide 2 5 6 Battery
47. irements Virtually all domestic PV installations will fall under the scope of Part P Part P requires the relevant Building Control department to be notified and approve the work There are two routes to comply with the requirements of Part P e Notify the relevant Building Control department before starting the work Documentation will be required and a site inspection by a Building Control officer may occur Building Control charges may apply w w PV Installation Guide Design Where a contractor is registered with a Competent Person Scheme as approved by the office of the deputy prime minister Building Control can be supplied with relevant documentation after the work is completed Documentation is self certified under the Competent Person Scheme and a site visit by Building Control is not normally required Part P also reinforces the requirement for the provision of an Electrical Installation Certificate to the requirements of BS 7671 see section 4 1 Note A copy of the Building Notice notification form can be found on the Local Authority Building Control website www labc services co uk Note At the time of writing there are no defined scope competent persons schemes to cover the installation of PV systems Until a PV defined scope scheme is available full scope schemes are applicable 2 5 Battery Systems This section of the guide covers the additional requirements where a battery forms
48. jacent to the PV array eg roof works to avoid potential damage or shading of the PV array Warranty e Warranty Information G83 1 INSTALLATION COMMISSIONING CONFIRMATION FORM This form is courtesy of the Energy Networks Association ENA and can be downloaded from www energynetworks org word ER G3 1 Appendix 3 doc Engineering recommendation G83 1 SSEG installation commissioning confirmation Confirmation of commissioning of a SSEG unit connected in parallel with the public distribution network in accordance with Engineering Recommendation G83 1 One Commissioning Pro forma per installation is to be submitted to the DNO Site details Property address inc post code Telephone number Customer supply number MPAN Distribution Network Operator DNO Contact details SSEG owner Contact person Contact telephone number SSEG details Manufacturer and model type Serial number of SSEG Serial number version numbers of software where appropriate SSEG rating A and power factor under normal running conditions Maximum peak short circuit current A Type of prime mover and fuel source Location of SSEG unit within the installation Location of multi pole isolator Appendix A cont Appendix B Installer details ELECTRICAL INSTALLATION CERTIFICATE Installer Note This certificate is courtesy of the Institution of Engineering and Technol
49. lation the covering must be opaque cover the whole array and be well secured A temporary warning sign and barrier must be posted for any period while live PV array cables or other d c cables are being installed Note Covering a PV array can provide a means to prevent the need for live working In practice however this is often difficult due to the practical problems of keeping the array covered as the installation proceeds and protecting the covering from the effects of the weather 3 3 4 Shock hazard safe working practices It is important to note that despite all the above precautions an installer or service engineer may still encounter an electric shock hazard Always test for the presence of voltage of parts before touching any part of the system Where a residual electric shock hazard is encountered live working practices must be adopted see above An electric shock may be experienced from a capacitive discharge a charge may build up in the PV system due to its distributed capacitance to ground Such effects are more prevalent in certain types of modules and systems namely amorphous thin film modules with metal frames or steel backing In such circumstances appropriate and safe live working practices must be adopted An example of where such hazards may be encountered is the case where an installer is seated on earthed metal roof wiring a large PV array In such circumstances the installer must touch the PV cabling
50. lug and socket connector or contained within a d c Junction Box see below However in certain limited circumstances it may be necessary for an in line cable junction to be made eg soldered extension to a module flying lead although this should be avoided if at all possible Note Great care needs to be applied in the design and installation of in line junctions Where unavoidable such junctions need to maintain the double insulated nature of the cables as described in section 2 1 4 eg by the use of two layers of appropriately rated adhesive lined heat shrink sleeving and be provided with appropriate strain relief Such junctions would typically be done off site prior to works using fittings and tools appropriate to the cable to be jointed 2 1 9 d c Junction Box If there is more than one string the d c junction box is normally the point at which they are connected together in parallel Junctions need to be made using high quality connectors typically screw terminals The box may also contain string fuses and test points The d c junction box must be labelled as PV array d c junction box and also labelled with Danger contains live parts during daylight All labels must be clear legible located so as to be easily visible and durably constructed and affixed to last Note A PV system cannot be turned off terminals will remain live at all times during daylight hours It is important to ensure that anyone op
51. mended before the next inspection is stated on Page 1 under Next Inspection This Certificate is intended to be issued only for a new electrical installation or for new work associated with an alteration or addition to an existing installation It should not have been issued for the inspection of an existing electrical installation A Periodic Inspection Report should be issued for such a periodic inspection The Certificate is only valid if a Schedule of Inspections and Schedule of Test Result are appended Schedule of inspections a Protection against both direct and indirect contact 0 SELV note 1 Limitation of discharge ot energy b Protection against direct contact note 2 6 insulation of ive parts Barriers or enciosures Obstacles note 3 Placing out of reach note 4 Prevention of mutual detrimental influence te Proximity ot non electrical services and other influences Segregation of band 1 and band It circuits band 11 insulation used Segregation of satety circuits Identification I w LI b Presence of danger notices and other warning notices Labeling of protective devices switches and terminals 0 identification of conductors Cables and conductors a Routing of cables in prescribed zones or within mechanical protection Connection of conductors Erection methods Selection ot conductors for current carrying capaci
52. n outside the equipotential zone This is to prevent the potential shock hazard should the supply neutral ever be lost PV Installation Guide Design 2 2 2 System earthing d c Conductor earthing The bonding to earth of any of the current carrying d c conductors is not recommended However as in the note below earthing of one of the live conductors of the d c side is permitted if there is at least simple separation between the a c side and the d c side including in the inverter Note In some countries it has been the practice to bond one part of the d c current conductors to earth eg earth connection at midpoint of PV string or earthed d c negative or for performance reasons on certain types of modules to earth the d c positive Due to the increased possible earth fault paths and possible problems with commonly available European inverter types and internal earth fault detection circuitry such practice should only be made when unavoidable any connections with earth on the d c side should be electrically connected so as to avoid corrosion 2 2 3 Inverter Earthing The inverter must be treated as standard electrical apparatus and earthed as per BS 7671 if Class 1 2 2 4 Lightning and surge protection Lightning can cause damage either from a direct strike or from surges due to a nearby strike Induced surges are the more likely cause of lightning damage in the majority of installations especially in rural areas
53. n proof Array frame correctly fixed and stable Roof fixings weatherproof Cable entry weatherproof Protection against overvoltage electric shock Live parts insulated protected by barrier enclosure placed out of reach or Class Il Array frame equipotential bonding present only relevant if required Surge protection devices present only relevant if required RCD provided only relevant if required Frame correctly integrated with existing LPS installation d c system Physical separation of a c and d c cables d c switch disconnector fitted to IEC60364 712 536 2 2 d c cables protective and reinforced insulation only relevant if required All d c components rated for operation at max d c system voltage Voc stc x 1 25 PV strings fused or blocking diodes fitted only relevant if required Address Location of distribution board a c system a c isolator lockable in off position only Inverter protection settings to local regulations Labelling amp identification General labelling of circuits protective devices switches and terminals to IEC60364 6 61 PV system schematic displayed on site Protection settings amp installer details displayed on site Emergency shutdown procedure displayed on site a c isolator clearly labelled d c isolator junction boxes suitably labelled Signs amp labels suitably affixed and
54. ng PV array cable output cable of a PV array PV d c main cable cable connecting the PV generator junction box to the d c terminals of the PV inverter PV inverter device which converts d c voltage and d c current into a c voltage and a c current PV supply cable cable connecting the a c terminals of the PV inverter to a distribution circuit of the electrical installation PV a c module Integrated module inverter assembly where the electrical interface terminals are a c only No access is provided to the d c side PV installation erected equipment of a PV power supply system PV Standard test conditions stc test conditions specified for PV cells and modules 250C light intensity 1000W m2 air mass 1 5 PV Kilowatts peak kWp units for defining the rating of a PV module where kW generated at stc PV self cleaning The cleaning effect on inclined PV systems from rain and wind etc PV Charge Controller A device that provides the interface between the PV array and the battery PV MPP Tracker Maximum Power Point Tracker the d c input stage of an inverter designed to maximise the input from the array Voc stg Open circuit voltage voltage under standard test conditions across an unloaded open PV module PV string PV array PV generator or on the d c side of the PV inverter Isc stcy Short circuit current short circuit current of a PV module PV string PV array or PV generator under standard test conditions d c sid
55. ng of the array and consequently at a poor point on the inverter efficiency curve depending on the inverter inverters are typically less efficient at low power levels PV array inverter ratios from 1 1 to 1 0 8 are commonly applied in the UK though in certain circumstances and depending on the inverter used ratios outside this are sometimes utilised NB Inverter power is taken to be maximum steady state a c power output Guidance on inverter array sizing can be obtained from the inverter manufacturers typically from system sizing software Inverter mpp range An inverter must be able to safely withstand the maximum array voltage and current as stated in section 2 3 3 However when chosing the most appropriate inverter for inverter performance purposes and when considering the matching of an array to the mpp range of an inverter an assessment can be made as to whether a narrower temperature band e g 10 c to 70 c maybe acceptable and appropriate for that particular site 2 6 2 System performance The output of a PV system depends on many factors such as orientation pitch shading and geographical location Estimating exact annual performance of a grid connected PV system is difficult however as a rule of thumb a south facing inclined plane unshaded array in the UK can be expected to generate on average 750 kwh per kWp installed per year Please note that this can be a conservative figure Note These figures are t
56. nies Distribution Systems Electricity Association 1991 www energynetworks org dg01 asp Note This is the Electricity Industry Recommendation for connection of generators It is applicable if the inverter is not covered under G83 1 e IEC 61215 Building Control Approval Crystalline silicon terrestrial photovoltaic PV modules Design qualification and type approval www iec ch Note This is the International standard for crystalline PV It specifies requirements for the design qualification and type approval of terrestrial photovoltaic modules suitable for long term operation in general open air climates as defined in IEC 60721 2 1 It References determines the electrical and thermal characteristics of the module and shows as far as possible that the module is capable of withstanding prolonged exposure in certain climates e IEC 61646 Thin film terrestrial photovoltaic PV modules Design qualification and type approval www iec ch Note This is the International standard for thin film PV It specifies requirements for the design qualification and type approval of terrestrial thin film photovoltaic modules suitable for long term operation in moderate open air climates e 61730 1 Photovoltaic PV module safety qualification Part 1 Requirements for construction amp IEC 61730 2 Photovoltaic PV module safety qualification Part 2 Requirements for testing www iec ch Note Part 1 is F
57. nt pvgis pv PVGISOEuropean European Joint Research Centre http re jrc cec eu int Communities 2002 2006 pvgis pv PVGISOEuropean Communities 2002 2006 Shading Shade makes a big impact on the performance of a PV system Even a small degree of shading on part of an array can have a very significant impact on the overall array output Shade is one element of system performance that can be specifically addressed during system design by careful selection of array location and layout and in the electrical design string design to ensure shade effects only one string Module temperature An increase in module temperature results in a decrease in performance eg 0 596 per 1 C above stc for a crystalline module Sufficient ventilation must be provided behind an array for cooling typically a minimum 25mm vented air gap to the rear For building integrated systems this is usually addressed by the provision of a vented air space behind the modules On a conventional pitched roof batten cavity ventilation is typically achieved by the use of counterbattens over the roof membrane and by the installation of eaves and ridge ventilation Note It may be possible to omit counterbattens with some integrated PV roofing products roof construction This is acceptable where there is test data showing that a specific integrated PV product and associated roof construction provide a similar PV cell temperature performance to a roof with a ventilated c
58. oc stc x 1 25 Array positive amp negative 120V 250V 0 25 MO shorted together lt 600V 500V 0 5MQ lt 1000V 1000V 1 MQ Separate tests to Array 120V 250V 0 25 MO positive and Array negative lt 600V 500 Voc stc 0 5MQ min 100V lt 1000V 1000 Voc stc 1 MQ min 100V Test voltage adjusted to prevent peak voltage exceeding module or cable rating FURTHER READING e BS 7671 2001 Requirements for Electrical Installations IEE Wiring Regulations Sixteenth Edition incorporating Amendments ISBN 0 86341 373 0 www iee org publish books WireAssoc e IEE Guidance Note 7 Special Locations 2nd Edition ISBN 0 85296 995 3 www iee org publish books WireAssoc Note IEE Guidance Note 7 Special Locations Chapter 12 covers Solar photovoltaic PV power supply systems as a special location as defined in IEE Regs The guidance is based on IEC 60364 7 712 Requirements for special installations or locations Solar photovoltaic PV power systems e Part P Electrical safety Building Regulations www odpm gov uk index asp idz 1130906 Note From 1st January 2005 people undertaking electrical work in homes and gardens in England and Wales have had to follow new rules in Building Regulations Virtually all domestic PV installations will fall under the scope of Part P There are two routes to comply with the requirements of Part P Notify the relevant Building Control dep
59. ogy and can be downloaded from www theiet org publications A schedule of items inspected together with a schedule of test results are to be included as part of this certificate Accreditation Qualification Address incl post code Form 2 FomNo 2 ELECTRICAL INSTALLATION CERTIFICATE notes 1 and 2 REQUIREMENTS FOR ELECTRICAL INSTALLATIONS BS 7671 IEE WIRING REGULATIONS Telephone number DETAILS OF THE CLIENT note 1 Contact person Fax number E mail address Information to be enclosed Final copy of system schematic SSEG Test Report Appendix 4 or web address if appropriate not necessary if already provided e g under stage 2 connection FON eg Va pirata dian Hi ow iced un ta cota ny Signatures below particulars of which are described above n e M my eA fw dose NUS Y PM eter tn bt ol puke ed nef rrr wih BS 7671 dato except for the departures any detaled Computer print out where possible or other schedule of protection settings Details of departures from BS 7671 Regulations 120 01 03 120 02 Electricity meter s make and model The extent of ability of the signatory or the signatories is limited to the work described above as the subject of this Certificate i For the DESIGN of the installation Where there is mutual lor the design Declaration to be completed by installer
60. ounterbatten space Inverter ventilation Inverters dissipate heat and should be provided with sufficient ventilation Clearance distances as specified by the manufacturer e g to a heatsink should also be observed Failiure to follow this can cause a loss in system performance as the inverter will de rate when it reaches it s maximum operating temperature This should be highlighted within the O amp M manual and perhaps with a label not to block ventilation placed next to the inverter 3 0 INSTALLATION SITEWORK 3 1 General Standard health and safety practice and conventional electrical installation practice must apply to the installation of a PV system Issues such as working on roofs or standard domestic a c wiring are covered thoroughly in other publications e g see HSE website www hse gov uk and are not detailed in this guide 3 2 PV Specific Hazards When compiling a method statement and risk assessment for the installation of a PV system there are a number of PV specific hazards that need to be addressed These will be in addition to standard considerations such as PPE Personal Protective Equipment working at height manual handling handling glass and the application of the CDM regulations e PV modules produce electricity when exposed to daylight and individual modules cannot be switched off Hence unlike most other electrical installation work the electrical installation of a PV system typically involves working on
61. part of a PV installation whether as part of a true stand alone off grid system or part of a hybrid e g grid linked batteries system Note The design and requirements of any of the load circuits within such a system are outside the scope of this document 2 5 1 PV array charge controller This provides the regulator dump interface between the PV array and the battery so as to prevent overcharging of the battery The unit may also provide other functions such as maximum power point tracking voltage transformation load control and metering Example Battery System ed R D 5 i Isi a f TE L papapapa EE Z Ea 44 Ea 4414 L 8989 84 84 ANTY HHTIOHLNOO 30HVHO e The charge controller must be rated for the current and voltage maxima see Section 2 1 2 minimum voltage and current ratings e The charge controller must be labelled as per the d c junction box requirements in section 2 1 9 e The charge controller must carry a CE Mark A full recharge is important for good battery health A small size cable between the charge control unit and the battery with an associated high voltage drop may lead to the control system prematurely halting the charge cycle These cables should therefore be sized for a maximum voltage drop of less than 196 at peak PV array output
62. ring special precautions see Regulations 413 04 and 471 10 7 Earth free local equipotential bonding not applicable in domestic premises only used in special circumstances see Regulations 413 05 and 471 11 8 Electrical separabon see Regulations 413 06 and 471 12 Appendix C Schedule of test results PV COMMISSIONING TEST SHEETS Note This form is subject to change as it is being worked on in the IEC Technical Committee 2 58 5 PV system Installation Check List of Installation address Inspection by Page Date Reference General installation electrical ref IEC60364 6 61 Equipment compliant with standards correctly selected amp not damaged Equipment accessible for operation inspection amp maintenance Equipment and accessories correctly connected Particular protective measures for special location Equipment and protective measures appropriate to external influences System installed to prevent mutual detrimental influence Conductors connected and identified Conductors selected for current carrying capacity and voltage drop Conductors routed in safe zone or protected against mechanical damage Presence of fire barriers seals and protection against thermal effects General installation mechanical Ventilation provided behind array to prevent overheating fire risk Array frame amp material corrosio
63. so see Planning for Renewable Energy A companion Guide to PPS22 which provides additional guidance for PV in Technical Annex 6 Active Solar Photovoltaics ISBN 1 85112 7542 e BRE Digest 489 Wind loads on roof based photovoltaic systems ISBN 1 86081 713 0 2004 www brebookshop com Note This Digest reviews the wind loading information appropriate for roof based PV systems and gives recommendations and guidance for the design of roof based PV systems for wind loads It covers both PV tiles or slates integrated into pitched roofs and PV modules mounted on or above pitched roofs e BRE Digest 495 Mechanical installation of roof mounted photovoltaic systems ISBN 1 86081 869 23 2005 www brebookshop com Note This Digest gives guidance on installing and using photovoltaic systems on roofs The guidance refers only to the mechanical installation of roof mounted integrated and stand off photovoltaic systems it provides best practice guidance on installation requirements and does not constitute fixing instructions References 1 Photovoltaics in Buildings Safety and the CDM Regulations BSRIA DTI Feb 2000 ISBN 0 86022 548 8 www bsria co uk bookshop system index html Note This covers larger systems although most of the safety advice is also relevant to small installations that may be exempt from the Regulations It provides a simple guide to the Construction Design and Management Regulations 1994
64. tallation use and maintenance e PV modules are current limiting devices which require a non standard approach when designing fault protection systems as fuses are not likely to blow under short circuit conditions e PV systems include d c wiring with which few electrical installers are familiar e The installation of PV systems presents a unique combination of hazards due to risk of electric shock falling and simultaneous manual handling difficulty All of these hazards are encountered as a matter of course on a building site but rarely all at once While roofers may be accustomed to minimising risks of falling or injury due to manual handling problems they may not be used to dealing with the risk of electric shock Similarly electricians would be familiar with electric shock hazards but not with handling large objects at heights 1 4 Parallel Generation A mains connected PV installation generates electricity synchronised with the electricity supply Installers are obliged to liase with the relevant Distribution Network Operator DNO in the following manner e Single installation covered by G83 1 notification at or before day of commissioning followed by G83 1 paperwork G83 1 appendix 3 within 30 days e Multiple installation covered by G83 1 application to proceed G83 1 appendix 2 On commissioning notification and appendix 3 as above Note For single installations of slightly greater than 16A attention is drawn
65. terminals is higher than the voltage at the consumer unit This voltage drop must be kept to a minimum in order to prevent the inverter nuisance tripping on over voltage Note New cables colours have been implemented under the current version of BS 7671 These colour changes became mandatory on 1st April 2006 Colour changes and the requirements for labelling in mixed colour installations can be found in BS 7671 and from IEE technical publications 2 3 2 a c switch disconnector A manual a c switch disconnector must be provided located in an accessible position within the Customer s installation as in G83 1 e g adjacent to the consumer unit or main distribution board which is in accordance with BS 60947 3 e must switch all live and neutral conductors must be securable in the OFF position only It must be simple to secure using a standard padlock devices that require a separate removable adaptor or special key to enable them to be secured are not acceptable e must clearly show the ON and OFF positions and be labelled as system main a c isolator Note At the point of installation of any a c switch disconnector the public supply Should be considered the source and the PV installation the load If the a c switch disconnector and the inverter s are not in the same room a local isolator should be installed adjacent to the inverter s This is to facilitate maintenance of the a c cable run and inverter s
66. this Cerificate is valid when they are amached to of Inspections and Schedules of Test Results are attached Erie Quarto of schedis wae Guidance for recipients This safety Certificate has been issued to confirm that the electrical installation work to which it relates has been designed constructed and inspected and tested in a cordance with British Standard 7671 The IEE Wiring Regulations You should have received an original Certificate and the contractor should have retained a duplicate Certificate If you were the person ordering the work but not the user of the installation you should pass this Certificate or a full copy of it including the schedukes immediately to the user The original Certificate should be retained in a safe place and be shown to any person inspecting or undertaking further work on the electrical installation in the future If you later vacate the property this Certificate will demonstrate to the new owner that the electrical installation complied with the requirements of British Standard 7671 at the time the Certificate was issued The Construction Design and Management Regulations require that for a project covered by those Regulations a copy of this Certificate together with schedules is included in the project health and safety documentation For safety reasons the elcetrical installation will need to be inspected at appropriate intervals by a competent person The maximum time interval recom
67. ting factors must also be applied BS 7671 Cables should be sized such that overall voltage drop at stc between the array and the inverter is lt 3 2 1 4 2 Cable type and installation method The cables used for wiring the d c section of a grid connected PV system need to be selected to ensure that they can withstand the environmental voltage and current conditions at which they may be expected to operate This will include heating effects of both current and solar gain Note Purpose designed PV cables are readily available These are simple to use comply with the requirements as above and allow simple and safe connection via purpose made PV plug and socket connectors It is expected most installations would use these cables Cables routed behind a PV array must be rated for a minimum temperature of 80 C Cables must be selected so as to minimise the risk of earth faults and short circuits This can be achieved by reinforcing the protection of the wiring either through a Single conductor cable both insulated and sheathed eg PV cable HO7RNF cables m p b Single conductor cable in suitable conduit trunking typically non conducting however earthed metal trunking may be required where additional mechanical protection is required Alternatively single core SWA may be a suitable mechanically robust solution A A c Multi core Steel Wire Armoured SWA only suitable for main d c cable and typically
68. ting voltage less than 207 V phase to neutral m Operating frequency greater than 50 5 Hz m Operating frequency less than 47 Hz e Dual supply labelling should be provided at the service termination meter position and all points of isolation to indicate the presence of on site generation and indicating the position of the main a c switch disconnector for suitable label see ER G83 1 or see the sample reproduced in Example Signs and on the back cover of this guide e At the point of interconnection the following information is to be displayed typically all displayed on the circuit diagram m Circuit diagram showing the relationship between the inverter equipment and supply m A summary of the protection settings incorporated within the equipment m contact telephone number for the supplier installer maintainer of the equipment NB It is also good practice for shutdown and start up procedures to be detailed on this diagram Note the requirements for larger systems connected under G59 1 including commissioning tests which may need to be witnessed are to be confirmed with the relevant DNO engineer as part of the connection application process 4 4 Labelling Requirements for labelling are contained within the relevant sections of this guide Example labels can be seen below All labels must be clear easily visible constructed and affixed to last and remain legible for the lifetime of the system Sign No Example Signs
69. ty 2 5 Battery systems 2 5 1 PV array charge controller 2 5 2 Battery overcurrent protection 2 5 3 Battery disconnection 2 5 4 Cables in battery systems 2 5 5 PV String cable and fuse ratings 2 5 6 Battery selection and sizing 2 5 7 Battery installation labelling 2 6 System performance 2 6 1 Inverter sizing 2 6 2 System performance 3 0 INSTALLATION SITEWORK 31 General 3 2 PV specific hazards 33 circuits installation 3 31 Personnel 3 32 Sequence of works 3 33 Live working 3 3 4 Shock hazard safe working practices 4 0 SYSTEM INSPECTION TESTING amp COMMISSIONING REQUIREMENTS DOCUMENTATION amp LABELLING 4 1 Inspection and testing 4 2 Array commissioning tests 4 3 ER G83 1 and G59 1 commissioning 44 Labelling 45 Operational amp maintenance manual Appendix A G83 1 installation commissioning confirmation form Appendix B Electrical Installation certificate Appendix C PV commissioning test sheets Further reading 26 26 27 27 28 29 29 29 30 30 30 31 32 30 33 35 35 35 36 36 36 37 37 39 39 39 39 40 42 43 45 47 51 GUIDE TO THE INSTALLATION OF PV SYSTEMS 1 0 INTRODUCTION 1 1 Scope The scope of this document is to supply system installers with information to ensure that a mains connected PV system meets current UK standards and best practice recommendations It is primarily aimed at small scale installations less than 16A per phase as per the scope of ER
70. ty and voltage drop Presence ot fire barriers suitable seals and protection against thermal effects General a Presence and correct location of appropriate devices for solation and switch LL Adequacy of access to switchgear and other equipment Oe D Ole 0 Choice and setting of protective and monitoring devices for protection against indirect contact and or overcurrent Ow Le Notes E to indicate an inspection has been carried out and the result is satisfactory to indicate an inspection has been carried out and the result was unsatisfactory N A to indicate the inspection is not applicable LIM to indicate that exceptionally a limitation agreed with the person ordering the work prevented the inspection or test being carried out 1 SELV An extra iow voltage system which is electrically separated from Earth and trom other systems The particular requirements of the Regulations must be checked see Regulations 411 02 and 471 02 2 Method of protection against direct contact will include measurement of distances where appropriate 3 Obstacles only adopted in special circumstances see Regulations 412 04 and 471 06 4 Placing out of reach only adopted in special circumstances see Regulations 412 05 and 471 07 5 Use of Class II equipment infrequently adopted and only 413 03 and 471 09 6 Non conducting locations not applicable in domestic premises and requi
71. undamental construction requirements Part 2 is Testing requirements These two international standards specify requirements for photovoltaic modules in order to provide safe electrical and mechanical operation during their expected lifetime They address the prevention of electrical shock fire hazards and personal injury due to mechanical and environmental stresses Pertains to the particular requirements of construction and is to be used in conjunction with IEC 61215 or IEC 61646 e IEC61215 Building Control Approval www odpm gov uk index asp id 1130474 www labc services co uk buildingreas default asp Note For integrated products in the UK where the PV forms part of the building envelope eg PV roof tiles proof of compliance with relevant Building Regulations may be required by the local Building Control Inspector eg compliance to e Fire resistance standards eg BS 476 part 3 gt Relevant wind uplift and weatherproofing standards eg BS 6399 BS 5534 See also BRE Digest 489 amp 495 below which are specific to PV e PPS22 Planning Policy Statement 22 Renewable Energy ISBN 0 11 753924 4 2004 www odpm gov uk index asp id 1143908 Note UK Planning Consent if required PPS22 replaces UK Planning Policy Guidance note PPG 22 It sets out the Government s planning policies for renewable energy which planning authorities should have regard to when preparing local development documents and when taking planning decisions Al
72. up of units connected in parallel the units need to have the same thermal environment and PV Installation Guide Design the same electrical connection resistance In larger battery banks fusing each parallel unit should be considered A typical connection configuration for a small series parallel battery bank take offs are on opposite corners The following warning signs are to be displayed e No Smoking or Naked Flames e Batteries contain acid avoid contact with skin or eyes e Electric shock risk xxx Vd c Note Circuit protection and all points of isolation should also be labelled with d c Supply xxx Vd c All labels should be clear easily visible and should be constructed and fixed so as to remain legible and in place throughout the design life of the system Protective equipment including appropriate gloves and goggles together with an eye wash and neutralising agent should be stored adjacent to the battery installation 2 6 System performance 2 6 1 Inverter sizing It is common practice for an inverter power to be less than the PV array rating and safety considerations with respect to sizing an inverter are addressed in section 2 3 3 However also to be considered is the system performance For example a 1kWp array connected to a 1 5kW inverter may be safe but not energy efficient with the UK climate the inverter will be operating for much of the time at less than the 1kWp rati
73. utilised where an underground or exposed run is needed le External cables should be UV stable water resistant and it is recommended that they be flexible multi stranded to allow for thermal wind movement of arrays modules Note To minimise the risk of faults cable runs should be kept as short as practicable Where long cable runs are required it is good practice to label along the d c cables as follows Danger solar PV array cable high voltage d c live during daylight This is to inform personnel involved in maintenance or alterations to a building at a later date See also section 2 1 12 additional d c switches for long cable runs Note Where modules are supplied with pre fitted single insulated tails containment should be installed as described in b above PV Installation Guide Design Note New cable identification colours have been implemented under the current version of BS 7671 see 2 3 1 The new identification colours for an unearthed d c circuit typical PV circuits are as follows Positive cable Brown Negative cable Grey Note BS 7671 requires that every core of a cable shall be identifiable by colour and or lettering numbering at its terminations and preferably throughout its length However in the special case where there is no possibility of confusion eg where cables are pre fitted with purpose made polarised plug and socket connectors additional cable colour alphanumeric id
74. val from DNO to be gained prior to works Commissioning in conjunction with DNO engineer or as required by DNO 2 4 2 Planning permission Guidance regarding the requirements for planning permissions for PV systems can be obtained in PPS22 Planning Policy Statement 22 Renewable Energy ISBN 0 11 753924 4 2004 available from www odpm gov uk The relevant planning authority and building control should be consulted at an early stage to determine any requirements that may apply Note Planning permission will be mainly concerned about the visual impact of the PV system Typically for domestic installations planning permission is not required can vary where property is affected by restrictions such as a conservation area etc Building Regulations approval may require the product to have passed the wind uplift water penetration and spread of flame tests see section 2 1 1 2 These will usually be applicable only where the PV is integrated into the fabric of the building 2 4 3 Building Regulations Part P Electrical safety From 1st January 2005 people undertaking electrical work in homes and gardens in England and Wales must follow new rules in Building Regulations Part P The changes have been made to e Ensure the safety of electrical installations e Ensure records are kept of work done e Provide electrical safety certificates that verify conformity of work these may be integrated into property selling requ
75. with relevant Building Regulations may be required by the local Building Control Inspector eg compliance with e Fire resistance standards eg BS 476 part 3 e Relevant wind uplift and weatherproofing standards eg BS 6399 BS 5534 BRE Digest 489 In future it is expected that all PV products will increasingly be covered by International standard IEC61730 2004 Photovoltaic PV module safety qualification Note IEC61730 Part 2 Requirements for testing describes the testing requirements for photovoltaic modules in order to provide safe electrical and mechanical operation during their expected lifetime It addresses the prevention of electrical shock fire hazards and personal injury due to mechanical and environmental stresses It outlines the requirements of testing and is to be used in conjunction with IEC 61215 or IEC 61646 2 1 2 d c System minimum voltage and current ratings All d c component ratings cables isolators disconnectors switches connectors etc of the system must be derived from the maximum voltage and current of the PV array This must take into account system voltage currents of the series parallel connected modules making up the array It must also take into account the maximum output of the individual modules Mono and multi crystalline silicon modules All d c components must be rated as a minimum at Voltage Vocstey X 1 15 Current lsc stc x1 Note When considering th
76. ypical for the UK up to 10 difference can be expected depending on position in the country and type of PV cells used etc it is recommended that a PV simulation is carried out using one of the PV simulation programmes available for an accurate estimation Orientation Chart Showing of yearly output available for various orientation tilts as of maximum 56 64 67 go 71 7 gi 7 6 65 58 Note Near horizontal 0 inclinations are not recommended as the self cleaning can not be relied on up to about 10 PV Installation Guide Installation Sitework Output varies with season The shape of the daily insolation curves and the monthly and seasonal trend in system performance is shown on the graphs below Bl Production per month Average Production per season kWh season July Global Irr clear sky Wim October Global Irr clear sky Wim April Global Irr clear sky W m January Global Irr clear sky W m 1100 1000 900 S 8 c 9 2 o Y go 800 700 5 60 600 E Z 500 T 5 Bs t 20 300 200 0 58 amp 8553 0 2 4 6 10 12 14 16 18 20 22 24 Spring Summer Autumn Winter Hours of day Month Season Example average daily isolation curves Manchester 300 Example average kWh electricity generation bar chart Inclination due South Ref European Joint Research Centre Manchester 30 Inclination due South 750kWh yr Ref http re jrc cec eu i

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