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10 watts off grid? A little can now go a L-O-N-G way! We look at Jaycar’s new “Sun in a Box” CIG Solar Lighting kit by Stan Swan siliconchip.com.au November 2008  17 Going bush? Living on a desert island/houseboat/mountain top? Sick of energy bills? Daily supply charges driving you crazy? Want to run extra wiring for decent shed lights but find that’s illegal? Even considering DIY by running a backyard generator instead? Read on – “CIGnificant” solar help may be at hand! P ortable 230V/12V petrol & diesel off-grid generators have long been popular, with cheap (~$1 per watt or less) offerings in most hardware stores. Aside from their use by farmers and tradesmen, in many remote regions the evening hum of the lighting generator is still almost as ubiquitous as a campfire. However, generator storage and maintenance hassles, noise, fumes (and of course the need to purchase, deliver and store costly fuel) mean TCO (total cost of ownership) of off-grid systems are increasingly expensive. Generator economics, even with remote regions facing fuel costs approaching $2 a litre, may seem “good value” and convenient against mains electricity at up to 20 cents per kW h “unit” (and more – see last month’s “Publisher’s Letter”). But are they good value? Each litre of petrol has a calorific value of around 36MJ (diesel is slightly higher but most small generators are petroldriven). As 1kWh = 3.6MJ (1000x60x60), this means a litre of petrol equates to some ten electrical units. With even the best fossil fuel generators only about 40% efficient in utilising this energy (most being wasted as heat), the electricity generated equates to a more costly 50 cents per kWh. Fuel storage and security, generator maintenance and eventual generator replacement need factoring in as well. In the Australian outback, the vast Pacific expanses and in “off the beaten track” New Zealand, a generator may still be crucial for running power tools and refrigeration. But for modest lighting and perhaps battery charging needs, it increasingly makes no sense to inefficiently use fossil fuels when alternatives abound. Fossil fuel lighting is now so costly for many subsistence Pacific and Asian communities that evening reading and learning is seriously threatened. Sailing vessels, especially, need to conserve fuel for emergencies, rather than frittering it away running on board electronics and cabin lights. The Jaycar MP-4552 CIS self-contained solar lighting system is a much better proposition. It’s much lighter, MUCH cheaper to run (energy from the sun is free until the Government works out a way to tax it!). With care, the supplied battery will last for years and even then they aren’t too expensive to replace. We’re very impressed with the CIS solar side of the kit; it’s a pity that it is somewhat let down by poor-quality lighting fittings. Still, these are replaceable at relatively low cost! The kit’s wiring diagram (significantly enlarged here straight from the instructions – they’re tiny!) should be straightforward enough for any handyman installer to follow. All parts –even the SLA battery – are included in the kit. 18  Silicon Chip Energy out of thin air Lighting alternatives? As this is a state-of-the-art electronics journal, we’re not talking wax candles and kerosene lamps (although soaring fuel cost have tragically meant increasing burns and dwelling fires from these), since small photovoltaic (PV) systems now abound. That’s right – energy straight from the maker, with no middlemen, almost every day! Although now almost disdained siliconchip.com.au at the garden lamp level, you really couldn’t want a better energy technology than PVs, as they’re reliable, unobtrusive, have no moving parts and offer at least a 20-year life. You’d be lucky to get 10 years from a petrol generator! Thanks to today’s efficient and bright white LEDs, even a few stored watts can now go a long way in pitch black conditions. A few watts? I’ve seen some Nepalese homes wired up at just 1W per household! It’s fitting that the very parts of the off-grid world most in need of lighting, such as Africa, are often those with abundant sunshine. Solar charging of cell phones and modest laptops, such as the ~6W models used in the OLPC (One Laptop Per Child) project, is also possible. It’s not widely appreciated that even polar and mountainous regions can use PVs, as their sunshine (although at low angle) is captured more efficiently when panels are cooler and the air is likely to be more clear as well. Compact solar panel prices in the ~10W range have fallen over the years to an attractive ~ $10 a watt, with larger 100W types around half this. However, in some ways PVs have been almost too much of a recent success story. Manufacture of the commonest mono & polycrystalline-silicon-based types is extremely complicated and costly and makers have been hard-pressed to ramp up for surging demand. Although silicon is the most abundant element on earth (sand being silicon dioxide), the refining needed for precision semiconductor work involves high temperatures and painstaking processes, with daunting setup costs and timeframes. It’s not quite as simple as just waving a blow torch over a pile of sand! “CIGS” you can light up indoors! It’s long been known that many other materials, such as Cadmium-Telluride (CdTe), show photovoltaic action but one of the most promising recently has been a brew of Copper, Indium and (di)Selenide (thus “CIS”). CIS PVs typically show energy conversion efficiencies of 10%, with enhanced “CIGS” types, (the G being Gallium, Ga) now reaching 19%! Although not yet as efficient as the best silicon-based panels, rugged CIS types are much cheaper to make and offer superior low light performance – an important feature in the hazy and overcast conditions besetting much of the world. Unlike cheap amorphous Si panels, with efficiencies typically only 5% and with output decreasing over time, CIS performance seems to actually improve with age – fine wine style. Manufacturers already eagerly adopting this CIS/CIGS approach include Honda (using a glass based process – others focus on flexible films), with investments from even silicon semiconductor giant Intel – “An Intel in every PV” perhaps? Many Asian makers have arisen but the CIS/CIGS market is presently dominated by Global Solar Energy (GSE) in Arizona, USA. Jaycar’s “Sun in a box” Although still very much leading edge, a 10W CIS panel is now retailing locally as part of Jaycar Electronics’ Self Contained Solar Lighting System – the Sun in a Box (Cat No MP-4552). This looks very timely indeed for all manner of modest DIY installations. This sub-$200 kit includes everything needed, including the solar panel itself, CFL and LED lamps, bases, fuses, switch, wire, a screwdriver and a standard 12V 8Ah SLA battery) to set up a convenient turn-key 12V off-grid system. A large part of the kit’s appeal may arise from its ease of carrying (underarm!) into remote regions and its suitability for unskilled installation and servicing – a significant issue in The 12V power socket on the developing countries’ “One Laptop Per Child” (OLTP) project allows charging (and running) directly from the Jaycar kit’s 10W CIS panel. In such applications, rather than sit around for hours in the blazing sun, it’s probably better to first charge a cheap “jump start” 12V 7Ah battery and then bring that indoors to the laptop. siliconchip.com.au November 2008  19 The lighting benefits of just 1W are readily apparent in this “available light” picture, with the kit’s LED cluster near dazzling in comparison to the LED torch on the left. many remote off-grid situations where licensed electricians may be in short supply but legally required. But . . . only 10 watts? Yes! 10W may seem trivial when spoilt by the sometimes kilowatts of lighting often found in homes today. (Don’t believe us? Count the number of halogen downlights found in most modern homes. Twenty of them equals a kilowatt!) However, the magnificent 12V 1W white LED clusters and 12V 5W CFL included in the kit dramatically transformed after-dark interiors and were found to especially suit such intensive activities as crafts, reading and cooking. Although torches and headlamps can help when off-grid, many a candle-lit evening has lead to singed hair, clothing and papers, undercooked and spoilt food, or dramas when cooking oil is confused with kerosene, toothpaste with sun cream etc. Even a little light in the right place can literally save your bacon! The kit’s directed LED clusters in fact seemed more useful than the “power hungry” glass CFL, which is easily accidentally damaged as well. Extra 12V white LED lamps could perhaps be instead added to suit and with the near trivial currents flowing, light duty wiring would suffice. Retrofitting such cool-running LED clusters into gutted bulkhead or quality reading lamps also appeals, especially since traditional filament lamp heat dissipation issues no longer arise. The kit’s 10W CIS glass panel (in 2 x 48 strips), is made up of 2 x 5W in parallel (thus giving some leeway against shadows and breakage) and incorporates an inbuilt 3A regulator (itself worth perhaps $30). This regulator prevents battery overcharge and also provides an 11.2V low-voltage battery disconnect. No lead-acid battery should be allowed to fall below this voltage of course, as plate sulphation then sets in. A recessed tri-colour LED shows (undocumented) activity and status – naturally this LED would be more informative if front or externally mounted (and if it was explained!). Performance The Jaycar CIS panel performance itself was excellent and even in sunny mid-winter New Zealand the setup pushed 0.69A into the partially charged 12V SLA – significantly exceeding the stated 0.58A IPM (maximum power current) rating. Heavily overcast skies with light rain still gave around 90mA, which compared very favourably with 100mA from a 20W polycrystalline silicon panel, confirming good lowlight and low-angle performance of CIS/CIGS. Interestingly, the above overcast CIS PV output fell dramatically when placed behind window glass (which of course absorbs near-infrared wavelengths), verifying that the IR resource (normally “wasted” by Si PVs) is well utilised by CIS when outdoors. Kit features The CIS kit’s panel includes a potted regulator which prevents both over discharge (harmful to any lead-acid battery) and excess charge. 20  Silicon Chip As the kit may appeal to the technically unskilled enthusiast for installation in demanding remote situations, several points emerge – both positive and negative, no pun intended! siliconchip.com.au Eventually, we knew there’s be a use for blown light bulbs: replace their contents with LEDs for low voltage systems! Be careful when breaking and removing the glass. If there is never a possibility of mains voltage being applied (eg, because there isn’t any mains!), such “repaired” 12V LED bulbs can be used in standard (mains-type) fittings . Positive: • The 10W CIS panel & regulator looks capable of being linked to a far larger capacity battery, since the supplied 12V 8Ah SLA would be fully charged in just a couple of sunny days. Information to suit the likes of an off-grid weekender would be beneficial, as further SLAs (or even a car battery) could be paralleled for greater energy storage during the idle week. 12V 7-8Ah SLAs are a cheap global standard and it’s often possible to scrounge slightly-used ones, free, from “mission critical” security firms. The extra battery capacity could then support heavier loads over a few days, with confidence that the system would recover during the week for delivery again the next weekend. • It’s typical with solar to assume a battery capacity at least three times the demand anyway, to take into account cloudy/ rainy days, etc. As the setup stands, just one evening’s use of all three lamps may drain the battery to shutoff levels – and if it rained the next day there’d be little prospect of a fresh charge. • The inbuilt regulator can only handle 3A, but a 12V car accessory/socket (Jaycar PP-1993 & PS-2003 etc) directly connected to the battery would allow short-term use of more demanding loads. A 12V to 230V converter, such as Jaycar’s can-sized 150W MI-5121, could even be directly connected to charge the likes of cordless power tools, laptops, cell phones, cordless toothbrushes and shavers. Being off grid doesn’t mean you have to rough it – but leave the 2kW hair drier and electric frypan at home! • A starter/power-pack (such the Jaycar MB-3596) could also be given a trickle charge, maybe then allowing jumpstarting of a car (or boat) in a remote region. Such a need ranks amongst the most frustrating when in the wilds, as a flat vehicle battery (due to perhaps parking with a door ajar and an interior light left on) in rough terrain can make push starting impossible and be perhaps even life-threatening. Negative: • The single A4 instruction sheet enclosed should really be enlarged/expanded with clearer terminal and connection diagrams. • We’ve commented in the past about the dangers of using low-voltage (ie 12V) lamps with normal 230V mains-type bases and the possibility of mixup. Unfortunately, all three provided 12V lamps are fitted with standard ES bases with sockets to match. While the CFL lamps are clearly labeled as 12V 5W, we believe it’s only a matter of time before one of these is mistakenly used in a 230V lamp circuit – with spectacular, albeit brief, results. The more costly, gorgeous LED clusters are not even labelled, meaning that the chances are even higher that they’ll be misused and destroyed. • The supplied lamp sockets appear to be of mediocre quality, without polarity indications and they do not cleanly grip the base of the LED lamps. These may then annoyingly lose contact or even fall out! We would seriously consider replacing them. • Despite our reservations about using mains-type fittings in a low-voltage system, if you were installing an off-grid low-voltage lighting system (where it was almost impossible that a mixup could occur), normal mains-type ES sockets could be used instead (albeit at extra cost). These fittings would have the advantage of being suited to fitting into luminaires and lampshades normally used in a mains lighting system. • A further benefit would be allowing your own LED clusters to be cheaply assembled, maybe as banks of three or four soldered in series inside an old (ES) lamp base. At last – a use for dead filament lamps! • The three supplied line switches are rather too-light-duty for prolonged use and details regarding more convenient wall mounted fixed types should be included. siliconchip.com.au Conclusion Although more costly than simple ~$40 “shed light” solar lighting systems, this “battery included” lighting kit looks great value and are especially suitable for modest off-grid users. The CIS panel and LED lamps were outstandingly efficient performers; however, attention to the light socket quality and type should be of high priority to ensure both system reliability and prevent disastrous 12V/230V lamp mix ups. Enhancement of the instruction sheets additionally could allow valuable off-grid charging applications, as it’s apparent that these could offer applications well beyond the intended lighting. TAFEs and universities could find just the CIS PV itself appealing! The Jaycar MP-4552 self-contained CIS Solar Lighting System is available from all Jaycar Electronics stores, dealers and on-line via www.jaycar.com.au SC November 2008  21