OFF GRID PV POWER SYSTEMS SYSTEM INSTALL GUIDELINES
Contents
1. SEIAPI S OD Sustainable Energy OFF GRID PV POWER SYSTEMS SYSTEM INSTALL GUIDELINES These guidelines have been developed by the Sustainable Energy Industry Association of the Pacific Islands in Collaboration with the Pacific Power Association They represent latest industry BEST PRACTICE for the design and installation of PV Grid Connect Systems Copyright 2012 While all care has been taken to ensure this guideline is free from omission and error no responsibility can be taken for the use of this information in the design of any PV grid connect system Issue 1 September 2012 Cy SEIAPI Ss Sustainable Energy GENERAL The performance of a reliable installation that fulfils a customers needs requires both careful design and correct installation practice and conformance to relevant standards STANDARDS for INSTALLATION Installation should follow any standards that are typically applied in the country or region where the solar installation will occur The following lists the relevant standards in Australia New Zealand and USA They are listed because some Pacific island countries and territories do follow those standards These standards are often updated and amended so the latest version should always be applied In Australia and New Zealand the main standards required are AS NZS 3000 Wiring Rules AS NZS 4509 Stand alone power systems AS 4086 2 Secondary batteries for stand alone power2. All cables should be sized to meet the maximum current e Cable losses between the PV array and the battery bank should never exceed 5 Cable losses between the battery bank and any DC load should never exceed 5 The following sizing methods based on voltage drops can be used for all types of currently available copper cable 1 The voltage drop Vq in volts is given by Vd 2xLxIxp 1000 where L route length of cable in metres current A p resistivity of Cu wire Q 1000 ft Note Resistivity values for copper wire at 75 are listed in Chapter 9 Tables 8 and 9 of the US National Electric Code The resistivity value varies for cables with different cross sectional areas 2 Voltage drop in volts per 50 ft 15 2 m of route length of twin cable using the above formula Issue 1 September 2012 Page 6 Z Wire Size AWG Notes mm Amps 0 5 1 0 1 5 2 0 2 5 3 0 4 0 5 0 7 5 10 15 20 25 30 40 50 14 2 08 0 16 0 31 0 47 0 63 0 79 0 94 1 26 1 57 2 36 3 14 4 71 12 3 31 0 10 0 20 0 30 0 40 0 50 0 59 0 79 0 99 1 49 1 98 2 97 10 5 26 0 06 0 12 0 19 0 25 0 31 0 37 0 50 0 62 0 93 1 24 1 86 8 36 0 04 0 08 0 12 0 16 0 19 0 23 0 31 0 39 0 58 0 78 1 17 6 13 29 0 02 0 05 0 07 0 10 0 12 0 15 0 20 0 25 0 37 0 49 0 74 0 98 1 23 1 47 1 96 4 21 14 0 02 0 03 0 05 0 06 0 08 0 09 0 12 0 15 0 23
3. 0 31 0 46 0 62 0 77 0 92 1 23 Ff 2 1 33 61 42 39 0 01 0 01 0 02 0 02 0 03 0 02 0 04 0 03 0 05 0 04 0 06 0 05 0 08 0 06 0 10 0 08 0 15 0 12 0 19 0 15 0 29 0 23 0 39 0 31 0 49 0 39 0 58 0 46 0 78 0 62 097 0 77 Shaded areas indicate that the cable ampacity might be exceeded at high temperatures Refer also to PV module and Inverter manufacturers recommendations SEIAPI Sustainable Energy CCC data from 2011 NEC Table 310 15 B 16 and resistivity values from 2011 NEC Ch 9 Table 8 3 Route lengths to produce 5 voltage drop 12V systems for twin cable using the above formula Maximum Distance in feet to produce 5 voltage drop 12V system Wire Size AWG 14 12 10 8 6 4 2 1 mm 2 08 3 31 5 26 8 36 13 29 21 14 33 61 42 39 Current A 1 95 5 151 5 241 9 385 6 611 0 974 0 1546 4 1948 1 2 47 8 75 8 121 0 192 8 305 5 487 0 773 2 974 0 3 31 8 50 5 80 6 128 5 203 7 324 7 515 5 649 4 4 23 9 37 9 60 5 96 4 152 7 243 5 386 6 487 0 5 19 1 30 3 48 4 77 1 122 2 194 8 309 3 389 6 6 15 9 25 3 40 3 64 3 101 8 162 3 257 7 324 7 7 13 6 21 6 34 6 55 1 87 3 139 1 220 9 278 3 8 11 9 18 9 30 2 48 2 76 4 121 8 193 3 243 5 9 10 6 16 8 26 9 42 8 67 9 108 2 171 8 216 5 10 9 6 15 2 24 2 38 6 61 1 97 4 154 6 194 8 11 8 7 13 8 22 0 35 1 55 5 88 5 140 6 177 1 12 8 0 12 6 20 2 32 1 50 9 81 2 128 9 162 3 1
4. Battery warning sign O DANGER Risk of Battery Explosion is permanently fixed outside the battery room enclosure in a prominent position Electrolyte Burns sign is permanently O fixed in a prominent position adjacent to the battery bank A fresh water supply is available for O eyewash and rinsing any acid spills 110 230 VOLT LV INSTALLATION All Low Voltage wiring has been installed O in accordance with local regulations This checklist is based on the Sustainable Energy Industries Association of the Pacific islands Installation Guidelines The guidelines demonstrate the latest industry best practice AUTHORISATION verify that the following system has been installed to the standard indicated by these guidelines Name of the person for whom the system was installed Date Attach a separate sheet detailing any departures Issue 1 September 2012 Page 9 Appendix 1 Table of Abbreviations and Acronyms d c Direct current a c Alternating current AS NZS Australia Standard New Zealand Standard UL Underwriters Laboratory ICC International Code Council NFPA National fire Protection Association ASCE American Society of Civil Engineers IEEE Institute of Electrical and Electronics Engineers Wh Watt hours kWh Kilowatt hours W Watts Wp Watts peak H hours V Volts A Amps VA Vo
5. below the top of the batteries PREVENTING EXCESSIVE CURRENT FROM BATTERIES Battery shorts are prevented by shrouding terminals and ensuring safe separation between live terminals Battery shorts are controlled by using appropriate circuit protection Overcurrent protection is to be provided in each battery output conductor except where one side of the battery bank is earthed ground in which case only the unearthed ungrounded conductor requires overcurrent protection Normal practice is to either fuse the positive and earth ground the negative or fuse all conductors ACID LEAKAGE Provision must be made to contain any spilled electrolyte Battery trays should be able to hold at least the electrolyte content of one cell of the battery bank ACID SPLASHES A ready supply of water should be available and any person working on the batteries should wear rubber gloves safety glasses and long sleeved protective clothing Eye wash equipment should be available in case of accident Walls near the batteries should be protected by acid resistant paint or non metallic sheet SAFETY AND WARNING SIGNS A battery explosion warning sign must be mounted so that it is clearly visible on approach to the battery bank An electrolyte safety sign should be mounted adjacent to the battery bank MAIN BATTERY PROTECTION Overcurrent protection and the ability to readily isolate a battery bank must be provided Issue 1 September 2012 Page 4
6. supplies AS NZS5033 PV Array AS 3010 1 Electrical Installations Supply Generating set AS 3595 Energy management programs AS 1359 51 Noise level limits AS 1768 Lightning Protection In USA PV systems must be in accordance with following codes and standards Electrical Codes National Electrical Code Article 690 Solar Photovoltaic Systems and NFPA 70 Uniform Solar Energy Code Building Codes ICC ASCE 7 UL Standard 1701 Flat Plat Photovoltaic Modules and Panels UL Standard 1741 Standard for Inverter converters Controllers and Interconnection System Equipment for use with Distributed Energy Resources DOCUMENTATION All complex systems require a user manual for the customer Off grid power systems are no different The documentation for system installation that should be provided include List of equipment supplied Shutdown and isolation procedure for emergency and maintenance Maintenance procedure and timetable Commissioning records and installation checklist Warranty information System connection diagram Equipment manufacturers documentation and handbooks for all equipment supplied Battery record logbook Generating set service logbook Issue 1 September 2012 Page 1 SEIAPI Ss Sustainable Energy PV ARRAY ORIENTATION AND INCLINATION For best year round performance a fixed array should be mounted facing true north 10 in South Pacific or True South 10 in North Pac
7. 3 7 3 11 7 18 6 29 7 47 0 74 9 119 0 149 9 14 6 8 10 8 17 3 27 5 43 6 69 6 110 5 139 1 15 6 4 10 1 16 1 25 7 40 7 64 9 103 1 129 9 16 6 0 9 5 15 1 24 1 38 2 60 9 96 6 121 8 17 5 6 8 9 14 2 22 7 35 9 57 3 91 0 114 6 18 5 3 8 4 13 4 21 4 33 9 54 1 85 9 108 2 19 5 0 8 0 12 7 20 3 32 2 51 3 81 4 102 5 20 4 8 7 6 12 1 19 3 30 5 48 7 77 3 97 4 CABLE PROTECTION All sub circuits including PV array and auxiliary charging circuits should be protected by HRC fuses or circuit breakers In addition these circuits being capable of being isolated without the use of tools Any circuit breaker used in DC circuits must be rated for the appropriate DC voltage and be non polarised Issue 1 September 2012 Page 7 SEIAPI S Sustainable Energy All cables used in the installation should be securely fixed in place to minimise any movement of the cable Any exposed cabling will be protected from UV and mechanical damage eg run in conduit Crimp style termination of wiring should use the appropriate crimping tool LICENCING EXTRA LOW VOLTAGE ELV All extra low voltage wiring should be performed by a competent person which is defined as a person who has acquired through training qualifications experience or a combination of these knowledge and skill enabling that person to correctly perform the task required LOW VOLTAGE LV All Low Voltage work gt 50V AC gt 60V or 120V DC should be undertaken in accordance with the regulatory requ
8. 3 rating of 500Ah therefore the charge current used in ventilation formula is 500Ah 100Ah x 0 5A 2 5A Note This is based on the charger either solar controller or separate grid power battery charger has an automatic overvoltage cut off If not maximum change current must be used SPARK IGNITION SOURCES Electrical equipment or storage for other equipment should not be mounted above the battery bank Connection or disconnection of any equipment at the battery terminals must not occur where there is any possibility of the presence of any hydrogen build up e battery charging equipment should be hard wired do not use temporary connection e battery terminals should be shrouded to prevent inadvertent short circuits e ensure sufficient clearance between battery terminals and metal walls or insulate using non metallic sheet e maximise separation between battery terminals e use insulated tools during any battery work Battery fusing preferably should not be in the same enclosure as the battery bank but if they are then they should be either a minimum of 500mm away from the batteries or 100mm below the top of the batteries Another method to keep the fuse separate from the battery bank is to place a vertical partition between the batteries and the fuse thereby keeping the fuse as close to the batteries as possible but isolated from any hydrogen build up In any case the main battery fusing should be located below the battery vents Normally
9. SEIAPI S Sustainable Energy To select the appropriate main battery protection e Obtain Time Current characteristics for the overload protection to be used All manufacturers publish time current information for their circuit breaker and HRC fuse ranges e Obtain inverter manufacturers data Continuous power rating Watts 3 to 10 second surge rating Watts Average inverter efficiency e For each inverter power rating determine the current drawn from the battery bank using Inverter Power Rating W inverter efficiency x nominal battery voltage NOTE Allowance for any significant DC demand must be included when sizing the main protection e Consult the Time Current characteristic to determine the appropriate rating CABLE SELECTION Metric Cables e All cables should be sized to meet the maximum current Cable losses between the PV array and the battery bank should never exceed 5 e Cable losses between the battery bank and any DC load should never exceed 5 The following sizing methods based on voltage drops can be used for all types of currently available copper cable NOTE the rated voltage or current carrying capacity CCC of any cable must never be exceeded eg some automotive types are rated at 32V 1 The voltage drop Vq in volts is given by Vd 2xLxIxp A where L route length of cable in metres current A p resistivity of Cu wire Q m mm 0 0183 Q A Cross Secti
10. e build up of leaves and other debris If fauna are a problem in the vicinity of the installation then consideration should be given to how to prevent them gaining access under the array see cable protection All supports brackets screws and other metal parts should be of similar material or stainless steel to minimise corrosion If dissimilar metals based on their galvanic rating are used then the two surfaces of the metals should be separated by using rubber washes or similar Where timber is used it must be suitable for long term external use and fixed so that trapped moisture cannot cause corrosion of the roof and or rotting of the timber The expected replacement time should be stated in the system documentation Any roof penetrations must be suitably sealed and waterproof for the expected life of the system If this is not possible then this must be detailed in Maintenance Timetable All fixings must ensure structural security when subject to the highest wind speeds for the region and local terrain This may require specific tests of the fixing substrate combination on that roof The installer shall ensure that the array frame that they install has applicable engineering certificates verifying that the frame meets wind loadings for that particular location The installer must follow the array frame suppliers manufacturers recommendations when mounting the array to the roof support structure to ensure that the array structure still meets w
11. he maximum output rating of the largest charging source or the rating of its output fuse or circuit breaker Where two parallel battery banks are used the charging rate is halved Best practice is to provide input ventilation vents below the level of battery and the output vents on the opposite side of the batteries as high as possible in the enclosure to prevent hydrogen build up VENTILATION Imperial Calculations Ventilation must be provided The minimum area required for natural ventilation for both inlet and outlet apertures for wet lead acid batteries are given by A 15 5q in Where q is the minimum exhaust ventilation rate in litres per second 0 006 xnxI and n the number of battery cells I the charging rate in amperes NOTE The charging rate in amperes is the maximum output rating of the largest charging source or the rating of its output fuse or circuit breaker Where two parallel battery banks are used the charging rate is halved Best practice is to provide input ventilation vents below the level of battery and the output vents on the opposite side of the batteries as high as possible in the enclosure to prevent hydrogen build up Issue 1 September 2012 Page 3 SEIAPI S Sustainable Energy VENTILATION VALVE REGULATED SEALED BATTERIES The charging rate I in the ventilation formula is 0 5A per 100Ah at the 3h rate C3 of discharge of battery capacity for lead acid batteries e g battery has C
12. ific at an inclination equal to the latitude angle in the tropics and latitude angle plus 5 to 15 outside of the tropics Between latitudes 10 South and 10 North the array should be tilted at a minimum of 10 degrees However the correct tilt angle should be determined based on energy usage and also the local weather conditions at different times of the year For example if an island typically has very cloudy conditions in one period of the year e g wet season then the array should be tilted to suit the sun s altitude in the sunny period of the year N y A True NORTH lt True South PV Module LATITUDE ANGLE SO p E g for PALUA Lat 7 LATITUDE ANGLE The tilt an j a gle should be approximately 7 H owever E g for SUVA Lat 18 S N because of the cloud cover in the wet season a The tilt angle should be approximately 18 Oe tilt angle of 20 would be better This would result in a greater energy output from the array in the dry season Figure 1a Figure 1b An alternative mounting arrangement can allow seasonal adjustment of array tilt to increase the energy input ROOF MOUNTING If the modules use crystalline cells then it is preferable to allow sufficient space below the array gt 50mm or 2 inches for ventilation cooling This will be subject to the constraints of the customer or architect It is important to allow sufficient clearance to facilitate self cleaning of the roof to prevent th
13. ind loading certification All external wiring must be protected from UV and mechanical damage in such a manner that it will last the life of the system Issue 1 September 2012 Page 2 SEIAPI S Sustainable Energy FREE STANDING PV ARRAYS These must be wind rated to meet the wind loading for the region BATTERY INSTALLATION LAYOUT OF BATTERY ENCLOSURE The main considerations for the battery enclosure are it must be safe with restricted access ie Prevent children easily accessing the batteries all equipment must be readily accessible for maintenance e it must have adequate ventilation e it should be vermin proof The main safety considerations are e explosion due to a spark in the presence of hydrogen build up e excessive currents caused by battery shorts e leakage of battery acid from battery cells e personal safety in the presence of acid To negate the risk of explosion there must be no opportunity for hydrogen to build up This requires adequate ventilation with no possibility of spark ignition VENTILATION Metric Calculations Ventilation must be provided The minimum area required for natural ventilation for both inlet and outlet apertures for wet lead acid batteries are given by A 100q cm Where q is the minimum exhaust ventilation rate in litres per second 0 006 xnxI and n the number of battery cells I the charging rate in amperes NOTE The charging rate in amperes is t
14. irements of the country Issue 1 September 2012 Page 8 INSTALLATION CHECKLIST PV ARRAY PV Array orientation Solar array is securely mounted and supported Timber used is suitable for external use or is properly sealed No dissimilar metals are in contact with the array frames or supports Roof penetrations are suitably sealed and weatherproof PV wiring losses are less than 5 at the maximum current output of the array PV wiring is protected by appropriate circuit breakers or fuses Wiring is protected from UV and mechanical damage BATTERY INSTALLATION Wiring is protected from mechanical damage The batteries are installed ina dedicated battery room enclosure or restricted access area Ventilation is in accordance with guidelines Acid leakage containment Batteries are not in contact with the floor of the enclosure room All battery interconnects and terminals are protected against accidental short circuit All crimp lugs have been fitted using an appropriate tool Battery bank is protected by C B or fuses All electrical equipment is mounted outside the battery enclosure room There are no exposed live parts on any installed equipment OOdodadda Oo OOO OO OOO OO SEIAPI hN Sustainable Energy EXTRA LOW VOLTAGE CABLING Cabling is sized to minimise losses in accordance with these guidelines O All sub circuits are protected by O appropriate fuses or circuit breakers SAFETY
15. lt amps Ah Amp hours PV Photovoltaic PSH Peak sun hours kWh m kWh m Kilowatt hours metres squared Voc Open circuit voltage volts Vino Maximum power point voltage volts lsc Short circuit current amps mp Maximum power point current amps LV Low Voltage gt 120V DC in Australian Standards ELV Extra Low Voltage lt 120V DC in Australian Standards UV Ultraviolet light HRC High Rupturing Capacity CCC Current Carrying Capacity Va Voltage drop CSA Cross Sectional Area of cable mm Cu Copper C B Circuit breaker Ff SEIAPI Sustainable Energy Issue 1 September 2012 Page 10
16. onal Area CSA of cable mm 2 Voltage drop in volts per 10 metres of route length of twin cable using the above formula Wire size mm 2 3 2 5 7 5 15 Amps CCC 15 20 25 45 70 0 5 0 09 0 06 0 04 0 02 0 01 1 0 0 18 0 11 0 07 0 05 0 02 1 5 0 27 0 17 0 11 0 07 0 04 2 0 0 37 0 23 0 15 0 10 0 05 2 5 0 46 0 29 0 18 0 12 0 06 3 0 0 55 0 34 0 22 0 15 0 07 4 0 0 73 0 46 0 29 0 20 0 10 5 0 0 92 0 57 0 37 0 24 0 12 7 5 1 37 0 86 0 55 0 37 0 18 10 1 83 1 14 0 73 0 49 0 24 15 2 75 1 72 1 10 0 73 0 37 20 2 29 1 46 0 98 0 49 25 1 83 1 22 0 61 30 1 46 0 73 40 1 95 0 98 50 1 22 Issue 1 September 2012 Page 5 SEIAPI Z h Sustainable Energy Notes Cable size and CCC from Pirelli automotive data Shaded areas indicate that the CCC is exceeded Refer also to PV module and Inverter manufacturers recommendations 3 Route lengths to produce 5 voltage drop 12V systems for twin cable using the above formula Maximum Distance in metres to produce 5 voltage drop 12V system Feurent ay smn smn 25mm amm omm tomm Tomm e foar a e wo wa as or o eof o a e wo ms os o se o e n o e o o s es a 65 90 e o a s e o o e0 we aa Ce o e so 75 es o Ca i se e a 70 r_ Ce e a _ 4 e oo v5 _ ss e as os oe ia _ Co 0 a o e e Ce e e e o Ce 22 a5 se es 0 Co eo l e hel e CABLE SELECTION Imperial Cables
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