File:Solar Lanterns Test
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1. Solar Lanterns Test Shades of Light On behalf of Partner for the Future I Federal Ministry d Worldwide for Economic Cooperation and Development IMPRINT Published by Deutsche Gesellschaft f r Technische Zusammenarbeit GTZ GmbH Postfach 5180 65726 Eschborn Germany T 49 61 96 79 0 F 49 61 96 79 11 15 E info gtz de www gtz de Authors Roman Gruner Stephan Lux Kilian Reiche Thomas Schmitz Gunther Photos Jurgen Gocke Frauenhofer ISE Design die Basis Kommunikation Ideenwerk Design Print Druckerei Klaus Koch Wiesbaden Eschborn May 2009 In their outward appearance the solar lanterns tested mostly resemble the kerosene lamps they are intended to replace SOLAR LANTERNS TEST SHADES OF LIGHT Torches and lanterns that obtain their energy from sunlight could replace environmentally damaging kero sene lamps in many developing countries and supply high quality light to a large proportion of poor house holds For this however the products must be well made and priced within the reach of the poorest people A laboratory test shows that there are still too few solar powered lanterns that meet both criteria Today more than 1 5 billion people in Africa Asia and Latin America live without the benefits of electricity When the sun goes down however their day is far from over when the daily work in the fields is done family and social life take over goods are sold at night markets a2. China South Africa Germany India Germany Germany India UK SEN Internet address www solarnest net www solux org www cosmosignite com www solux org www sollatek com www astsolar com www astsolar com www ma www solenergycc com Module external external external external external external external external external external 12 V socket battery Radio can be 3 brightness 6 V socket mobile steplessly Radio Additional utility 2 brightness levels 12 V socket charger unit connected levels 3 phone charger dimmable flashing light AALEN test EEE BEE BE EEE DER EEE BEE EEE EEE EEE ES N Visual examination lantern O o WER a DIS EE MEV Cycle test degradation Overview of marks 1 0 1 4 very good 1 5 2 4 good 2 5 3 4 satisfactory 3 5 4 4 poor 4 5 5 0 very poor costs approx USD 8 more 3 Alongside the model tested the manufacturer produces a similar model that includes a mobile phone Costs 4 In early 2009 the manufacturer offered a one lantern version of this system for about USD 350 CIF price to GTZ 5 The manufacturer announced price reductions in 2009 Price to performance winner 6 In early 2009 the manufacturer announced improved battery charging and price reductions of about one third 7 According to the manufacturer the Glowstar price has fallen in 2009 Photo Gocke The Shortlist Thus seven solar lanterns reached the se
3. exhibits de fects in workmanship and offers only a poor solar fraction and modest light duration Outlook The quality of solar lanterns on the market is mixed and prices are still too high for them to sell in great numbers in view of the low saving rates of poor households However we expect prices to drop below 50 of 2008 values over the next few years which will make solar lanterns clearly more economic than kerosene lamps As they offer higher quality lighting better handling environmental advantages and sometimes radio or mobile phone charging massive market growth can be expected in the near future despite the limiting influence of higher upfront payments for solar lanterns which can only partly be addressed through cred its In light of the mixed test results informing potential consumers about lantern quality will be of great importance for a healthy market development Photo Gocke 10 Testing Criteria Preliminary Test The distribution of marks in the preliminary test is based on the following examiner s checklist Does the lantern function How is the distribution of light Does the lantern cause glare Is the switch mechanically robust Can an illumination be created on a level surface that is sufficient to allow reading writing Operating elements displays and reflector usefully arranged Robust housing Wiring and components firmly fixed Components correctly placed and sol dered to PCB
4. nominal rated values of power output open circuit voltage and shortcircuit current If these are less than 90 of rated value deduct 2 marks For absence of impact protection fixing options or strain relief or for a cable length lt 5 m deduct mark each Deviation from battery capacity Do the test results for battery capacity agree with the rated capacity 1 mark deducted for a deviation of more than 10 2 marks for a deviation of more than 20 Loss of battery capacity during continuous testing This test applies only to NiMH batteries Is the battery resistant to over charging How does capacity hold up under a continuous load Loss of over 5 deduct 1 mark over 10 2 marks over 15 3 marks over 20 4 marks i e a mark of 5 Charge controller Of concern here besides the efficiency of the controller is particularly the protection of the battery against discharge and overcharging load rejection the power con sumption of the controller and signalling For efficiency deduct 1 mark per step as follows less than 90 less than 80 and less than 65 If there is no charge controller at all deduct 2 marks if there is a likelihood of damage to the battery Lack of load rejection also deduct 2 marks If it is not possible to recharge fully discharged batteries deduct 4 marks Efficiency of ballast device How good is the efficiency of the ballast If less than 90 deduct 1 mark less than 80 deduct a furth
5. Printed Circuit Board Cables correctly soldered or crimped Switch function given Socket mechani cally stable Splash guard provided Handle robust Reflector and cover glass unbreakable or protected Does lantern holder ensure reliable contact For CFL illuminants can the electrodes be pre heated With LED illuminants is a high quality brand name LED used In the case of power LEDs is an appropriate heat sink fitted Does the ballast allow constant lumi nous flux irrespective of the battery charge state Is a charge controller provided to prevent overcharging or deep discharge Weather protection Is weather protection a splash guard evi dent Is the cable weatherproof and long enough or must the lantern be charged outdoors Is the module mechanically robust and resistant to ageing aluminium frame glass cover Are the connection points protected from moisture Is strain relief provided for the cable connector Is there one and is it easy to understand The overall mark for the preliminary test is obtained from the average of the individual marks Serious defects may lead to a failure result and exclusion from the main test Testing Criteria Main Test The system for marking in the main test begins with a base value of 1 for each category from which points are deducted for indi vidual faults or shortcomings These are assessed as follows Deviation of solar module from nominal rating Does the system deliver the
6. cond testing stage of which four are German made the So ux LED 100 and Solux LED 50 of the Solux e V development assistance project the Solar 2007 1 by the Freilassing solar promo tion project and the sun x set mobile produced by W rth Of these the products of the two non profit projects make an impression with their individual and functional design while the system design from the manufacturer W rth drops out of the picture since it offers two lanterns and a separate charging station allowing for a variety of addi tional functions such as operation of a radio This product therefore comes closer to a solar home system a fact that is reflected in the price Alongside these the shortlisted systems included the Glowstar GS7 of the British com pany Sollatek the Aishwarya NEST 6543 of the Indian manufacturer Noble Energy and the Mightylight 3040 also Indian made The latter model was one of the first mass produced products in this market sector and may have the widest distribution of all the products tested The ISE test engineers still noted a number of shortcomings even in the preferred models They criticised the Glowstar for wrongly designed circuitry the Aishwarya was not considered suffi ciently robust the Solux LED 100 and Solar 2007 1 lacked current control for the LEDs as did the Mightylight which also did not have any form of charge control The examin ers found shoddy workmanship in the Solux LED 50 and criticised th
7. e significant divergence in quality in the sun x set mobile between the Chinese made lighting systems and the well constructed base charging station Major Differences in the Main Test The seven selected systems were subjected to an indepth laboratory examination The actual output of the solar module was compared with that specified by the manu facturer The capacity of the batteries was examined with NiMH rechargeable batteries further subjected to a dura bility test The charge controller was checked for efficiency and discharge protection and the ballast for efficiency An additional cycle test was carried out on the CFLs for switching endurance The central issue of the laboratory examination was however the testing of the light perform ance criteria measuring the luminous flux and luminous efficacy and calculating the solar fraction of the lanterns Finally the maximum light duration on a full battery was measured Operating costs of the products were established in addi tion to the technical testing in terms of both the lifetime of the batteries contained in the system and the actual light output While the calculation of monthly running costs based on lifetime should be structured in terms of a typi cal customer s use to allow a direct comparison with the costs of kerosene or candles the calculation of measured light output is more complex yet is the one on which the value for money of the systems can most fa
8. eap kerosene lamps give off other emissions that are harmful to health and pose a significant fire risk An Alternative Solar powered Lanterns In an effort to curb this wasteful use of resources devel opment organisations have been propagating alternative lighting technologies for two decades among them so lar powered solutions In these devices solar cells convert sunlight into electricity during the day that charges a bat tery which then produces light for use after dark The most common lighting source used in such solar systems is the compact fluorescent lamp CFL though recently more efficient light emitting diodes LEDs have become more widespread Progress in solar technology has recently led to a growing use of solar powered lighting solutions in developing coun tries Particularly in rural areas with a dispersed population where connection to the electricity grid would be uneco nomic solar lighting systems are a promising alternative Solar lighting systems may broadly be divided into three classifications simple models similar to ordinary torches are already available in many countries for a retail price of about ten US dollars These are sometimes sold with a crank dynamo in place of the solar cells Luminous efficacy and durability are usually poor Such low cost lanterns often last for only a month or give light for only a few minutes At the other end of the price scale are solar home systems with a so
9. er mark Cycle test degradation How long do CFL lamps last when subjected to a switching cycle of on for 60 seconds off for 150 seconds For failure before 10 000 cycles deduct 1 mark For LED systems is there a significant fall in light output from the LEDs If the luminous flux falls by 25 after 1000 hours de duct 1 mark by 30 deduct 2 marks by 35 deduct 3 marks Breakage test Are the lanterns seriously damaged by the impact of falling onto a hard floor from the edge of a 60 cm high table For total failure deduct 1 mark otherwise pro rata Luminous flux Luminous flux in phi lm is measured over a period of 210 minutes and the average value determined If this value is less than 100 Im the mark is 1 5 less than 80 Im 2 0 less than 60 Im 2 5 and less than 40 Im 3 0 Luminous efficacy Here again the average is obtained from a period of 210 minutes beginning from a fully charged bat tery Above 40 lm W luminous efficacy 1 5 marks less than 40 lm W 2 0 less than 30 lm W 3 0 and less than 20 Im W 4 0 Solar fraction The proportion that the solar system can meet of daily need here assumed at 3 5 hours lighting per day was determined for five simulated locations Bolivia Senegal Indo nesia Mozambique and Uganda Less than 95 cover deduct 1 mark less than 90 deduct 2 marks Light duration The duration is measured until luminous flux falls to 70 of the initial value If the maximum li
10. erformance comparison In the good technical category two other products are ranked behind this model both from German develop ment initiatives The systems did not achieve a better rank ing because of their unsatisfactory solar modules While the Solux LED 100 otherwise deserved a very good rating in technical terms the weak light output of the Solar 2007 1 counted against it Taking into account their substantially higher price both systems fall by one grade Their purchase price is higher than the annual lighting costs of the typical target household and the running costs are also substan tially higher than those of most other systems examined Thus in terms of value for money the two German solar lanterns fall behind the systems technically assessed as sat isfactory In this category the second Indian system the original Mightylight shows up well Here a better technical assessment is prevented mainly by the poor battery durabil ity and the lack of a ballast The manufacturer has how ever prompted by this test result already brought an im proved version to market The German So ux LED 50 just succeeded in gaining a positive rating for its price perform ance The chief fault on this especially bright and handy lantern is its lack of weather resistance The Glowstar failed both the technical test and in terms of value for money This unusually heavy and cumbersome lantern was a pioneer of the market sector but
11. ght duration is less than 7 h mark as 1 5 if it is below 6 h 2 0 if lower than 5 h 3 0 and if lower than 4 h 4 0 In the main test the overall mark is derived by averaging the indi vidual marks and applying the percentage weighting specified Testing Criteria Costs Purchase price Because of strong fluctuations of local customs duties and taxes and in order to assure the comparability of de livery costs the purchase price is given as the CIF price in the port of discharge At current annual lighting costs for a target household of some USD 60 for kerosene and candles the actual annual figure varies sharply with income and use patterns the maximum purchase price for high quality solar lanterns at an early stage of the market should be of the order of half this amount Monthly running costs battery durability The purchase price is divided over the service life which is mainly determined by the life of the battery It is assumed that the user does not change the batteries The life of the better solar systems tested exceeds 2 years without change of battery Operating costs per kilolumen hour Here the price is es tablished in relation to the light output of the lantern over its lifetime Since the light output of traditional light sources is often very weak the merits of solar lighting in terms of the quality of the lighting are important This value should there fore be considered in addition to the purchase cost a
12. irly be based To get a yardstick for the price to performance ratio the running costs obtained in the test must be placed in rela tion to other forms of lighting see Table 1 However the running costs can only be considered an approximate basis for calculation This is primarily because the durability of the battery can only be estimated very crudely Test Results The winner of the technical test was without doubt the sun x set mobile Even if the two lanterns do not show the best workmanship the system functions with the largest and most powerful module by far and with an outstand ingly good and versatile charging station The extremely high purchase price and consequently huge operating costs however force this system unequivocally out of the range discussed here These are almost ten times the comparison costs of kerosene lamps thus making any argument that the target group should adopt this new lighting system untenable Certainly the high quality charging unit of fers a whole range of additional functions But in this price bracket the potential customer will probably opt for a solar home system or a diesel generator Of the systems rated good in technical terms the Indian Aishwarya stands out because of its especially favourable price It failed to at tract a better technical evaluation only because of its faulty ballast and minor issues in workmanship The Aishwarya is therefore the clear winner in the price to p
13. lar module of 20 to 100 watts and an optimised car battery capable of powering several lights a radio and a TV set simultaneously Although some three million such solar home systems have already been installed worldwide for most users they remain unaffordable in Africa and Latin America they cost between 500 and 1000 US dollars Only in Asia are they somewhat less expensive For its testing of PV lighting technology therefore GTZ German technical cooperation has concentrated on a third product category which is rapidly gaining impor tance solar lanterns or pico PV systems whose retail prices currently fall between the two extremes above In their out ward appearance they resemble kerosene lamps but they promise greater lighting convenience and minimal running costs In most models available so far a small solar module typically with a capacity of 3 to 10 watts is separate from the lantern so that it can be placed outdoors without the lantern being exposed to the weather The best of these lanterns can be hung indoors or placed on a table but are also portable enough to light the way when walking at night Another way in which these pico PV systems stand out from simple solar torches is the auxiliary uses available on many newer models These offer outputs for a radio a mobile phone charger or other functions thus making a minimal basic provision of electrically powered micro devices conceivable for all poor
14. nd kiosks and community centres become meeting points for village locals Not until late at night do housewives find the op portunity to sew or do housework and many students only get down to work after nightfall Lighting for these colourful scenes comes in many forms The wealthy are able to afford diesel generators while the poorest must make do with candlelight and the glow from the fire But the most common source of artificial light in countries such as Kenya Peru and Afghanistan is the kerosene lamp ranging from simple low cost wick lamps to the high quality pressure lamps with gas mantles that are popular among campers in Europe The luminous effi cacy of many traditional methods of lighting is very low and also poor value for money lamp oil and candles cost a typical household in developing countries some 40 to 80 US dollars per year actual expenses vary greatly depending on international fuel prices national taxes and household behaviour Kerosene A Local and Global Environmental Hazard According to a report published in the American scientific journal Science in 2005 77 billion litres of fuel are burned in kerosene lamps every year That amounts to 1 3 million barrels of oil per day The oil consumption of these tradi tional lamps represents about one third of worldwide pri mary energy demand for domestic lighting and is responsi ble for emissions of 190 million tonnes of CO greenhouse gas per year Moreover ch
15. nd monthly operating cost in order to correctly assess the value for money of the products Note on cost calculation Acceptance of this environmentally friendly system of lighting is heavily restricted by the low level of liquidity of the target group households in all developing countries Although the operating costs of the solar lanterns in a full cost calculation are lower than those of most traditional alternatives because no more maintenance costs are incurred the purchaser still incurs roughly a year s lighting costs in ad vance For the annual lighting costs therefore a price limit for solar lanterns may be expected Credit from dealers or through microcredit institutions is still rare in this market sector 11 o BATTERY Ena Enw a U fi TT GA LA ____VeurdeliGHT Deutsche Gesellschaft f r Technische Zusammenarbeit GTZ GmbH Dag Hammarskj ld Weg 1 5 65760 Eschborn Germany T 49 61 96 79 0 F 49 61 96 79 11 15 E info gtz de www gtz de ko Wort
16. ro Here again the solar module is built into the lantern and not weather protected A loose con tact in the switch and a foot that comes off only add to the poor impression Nor did the two lanterns from the Chinese manufacturer Astral Solar pass the preliminary test The CFL based Astral ASO18 failed on the basis of sloppy physical construction with wiring that broke off defective switches faulty elec tronics and a lack of weather protection The Astral AS021 displayed similar shortcomings in workmanship such as poorly soldered joints The cable between lantern and solar module is so short that the lantern must be placed out doors along with the module Moreover the LEDs used are unfavourably wired resulting in a very low efficiency The decisive factor in failing this system however was the lack of deepdischarge protection As a result the battery will be damaged in a very short time Solar Lanterns Test pico PV systems Product photo Sun x set mobile Aishwarya NEST 6543 Solar 2007 1 Solux LED 100 Mightylight 3040 Solux 50 Glowstar GS7 AS018 AS021 MS01 SLI000SW Wuara 2212SL Noble Energy Solar Solarprojekt Cosmos Ignite Astral Solar Astral Solar Macro Solar Global Marketing SolEnergy Africa Solux e V Sollatek Ltd Technology Co Technology Co Technology Co Ltd Technologies Inc PTY Ltd Manufacturer W rth Solergy Technologies Ltd Freilassing e V Solux e V Innovations Germany China China China
17. rural populations in the near future Shoddy workmanship which compromises the durability of a system can usually be recognised at sight Following exhaustive research on solar lanterns currently on the market twelve promising models were selected for technical examination and tested by the Fraunhofer Insti tute for Solar Energy Systems ISE in Freiburg Germany This examination is the preliminary stage of a field test that GTZ plans for 2009 Experience in development coopera tion shows that one thing must be avoided at the outset that users of cheap and inadequate devices should become so disillusioned that the entire technology is discredited Table 1 Cost comparison Lighting system Typical cost USD klmh Candle 2 00 Kerosene lamp 0 10 1 00 Solar lanterns 0 10 4 00 Solar home system 0 04 Mains electricity 0 01 Estimated unit costs of lighting from different sources measured in kilolumen hours Kerosene prices fluctuate widely Lighting costs of better solar lanterns are currently roughly at par with kerosene lamps Several solar lantern manufactur ers have announced significant price reductions for 2009 Phi lm 0 500 1000 1500 2000 2500 t h ASO21 e SOLAR 2007 Mightylight 3000 3500 4000 The luminous flux of the Astral AS021 dark blue curve falls sharply relative to other tested solar LED lanterns after only 100 operating hours SOLUX 100 Graph 1 Degradation of the light output of poor lo
18. w power LEDs The Preliminary Test In an initial testing phase ISE examined all twelve systems for quality of workmanship Five of the worst examples were eliminated and not passed to the next stage of test ing Simple methods that can be performed with ease in developing countries were used to test the function ing of the devices Mechanical and electrical parts such as soldered joints and plug connectors were examined for durability and the layout of the electronic components the weather protection and the exterior quality of the solar module were evaluated One of the few models in which the solar module is built into the lantern the Chinese Global Marketing Technologies SLIOOOSW failed because the fold out mechanism for the module is not robust the module itself is poorly made and not resistant to rain In addition the main switch did not function correctly The Macro Solar MS LO1 from China was also rejected because of its very low light output The unit s 14 LEDs give very inconstant light after only 30 minutes luminous efficacy fell to around 20 The most poorly constructed solar lantern in the test was the Wuara 2212 SL from a South African company whose price however at about ten dollars is also extremely low But its performance does not even live up to this low price With its poor LED output the system most closely resem bles a cheap garden lantern after two hours light output falls to practically ze
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