Solar Lantern Programmes - A brief watchlist.

Too many people and bodies, unfortunately including media like NDTV Green Campaign, seem to carry an impression that a chargeable torch or battery-powered lamp is a solar lamp by itself and that, donating one to a village family means immortality to all concerned. To top it, some of them have displayed ignorance of the difference between a solar thermal and SPV or photovoltaic panel. Nothing is more damaging to the credibility of the solar energy programme than these amateur freebies.

1. The lantern, most importantly, needs to be compatible to a solar SPV panel, which often costs more than the lamp itself, in the region of Rs 250 per Watt. Typical power ratings of crystalline silicon panels manufactured in India are 6W, 10W and 35W, for this purpose, by Tata BP, SELCO, Solkar, CEL, BHEL, Udhaya Semiconductors, etc. You may thus calculate the budgetary costs. More notes on techno-economic calculations for SPV systems can be found at http://micropower.blogspot.com/2003_11_23_archive.html



2. The energy drained from the lamp's battery each night, in Watt-Hrs should match the panel power rating in Watts X 4.5 hrs, i.e. the solar panel must feed its power in 4.5 hours what has been drained all night by the lamp's battery. This calls for correct matching and supply of a solar panel of adequate capacity and correct voltage for safe and reliable charging.



3. For battery durability and system-level reliability, the battery must not be drained for more than 20% of its stored capacity in a day, on average. While we provide for this in indoor and outdoor stationery lighting systems by using slow-drain Class-100 or Class-120 batteries, compact lantern manufacturers typically use a hi-drain, hi-charge C-5 battery which drains its full charge in just 5 hours. This is why batteries in solar lamps wear out in 3 years or less.



4. Another issue is the light source. Reading and activities involving inspection require 300 Lux i.e. 300 Lumens per Sq Mtr. The recent trend is to use white LEDs, which deliver mostly in the region of 20-30 Lumens per watt consumed, as against a filament lamp that delivers 15 Lumens and a 230V Commercial-grade CFL that delivers 44 and a tube-light that delivers 40 Lumens per watt respectively. Often, the quality of LED lights are questionable for eye safety, unless certified by a manufacturer.



5. Beside quality and quality of light, each light source has a limited life. A standard replacement should be available locally or provided for, the battery as well as LED, tube or bulb used.



6. The beneficiaries need to be taught to connect and place the panel correctly and clean it daily, in order to get the right amount of power. Often, there is no indication of light source or output in Lux or Lumens of the lanterns in the manufacturer's information. We do not even know how for many hours the lamp will glow on full charge, in one day.



7. The manufacturer or donor must address the above issues.



8. In India, it may be wise to contact the appropriate State Nodal Agency for a list o0f their approved manufacturers, because State Nodal Agencies typically undertake execution and follow-up of such programmes, even privately and charitably funded.



9. Alternately, I would suggest procuring the smallest rated but reliable, warranty-supported solar panel and approaching a manufacturer like Eveready, who have recently entered the solar lantern space and have a reasonably penetrated rural marketing network, for support in lantern servicing as well as replacement of battery and light source.

The Barefoot College in Rajasthan under the stewardship of Bunker Roy is a good example, where local persons are first trained and micro-entrepreneurs enabled to service solar lanterns. So is GEDA in Gujarat, for community-owned lighting installations like streetlights.

The country's first State to take up solar energy in earnest saw good and bad cases too. While Gujarat's State Nodal Agency GEDA (www.geda.org.in) managed few hundred streetlights a year in the late 80s by providing solar stills for distilled water to refill lead-acid batteries (sealed batteries were not available locally then), training owners and incentivizing local monitors, the SEBs or State Electricity Boards including GEB bombarded the villages with 1000-3000 streetlights and never bothered to check, with the result that all had failed by 1991-92, causing a massive loss in monetary and credibility of the SPV program. However, on the other hand, a good proportion of the ones installed and facilitated by GEDA with the village administrations' enthusiasm, continue to light up their habitats, to this day.