Even after 20 years of solar lighting systems being used in rural areas, the concept has failed to take off and provide the required local lighting solutions primarily due to:

• Use of high powered, low illuminating CFLs, which have low power factor and need high starting current (low powered LEDs are now being used in some cases).
• Use of lead acid batteries, which have memory effect and low DOD (depth of discharge) and do not perform well in very high and low temperatures (these are rated for 25? and appropriate temperature compensation circuits are needed).
• Mismatch between charge and discharge - often a 7 W CFL (with 0.7 PF is powered by a 6 V 4.5 battery or 12 V 7 AH), thus leading to faster depletion of battery and low autonomy.

Global Teleinks has introduced Arundhati Solar Lantern, which has some unique features:

• Wastage through
• High powered 1 W LED lantern
• Unbreakable ABS body
• Highly efficient Li Ion battery with twice as many charging cycles than the industry norm lead acid battery
• Minimal pollution when battery is discarded
• Step switching to enable long cycles times varying between 4 to 20 hrs with single lithium battery and 8 to 40 hours with double battery
• Low wattage of solar pane to charge the battery thus reducing the cost of the lantern, enhancing the physical and functional life of lantern due to the use of LED (35000 hrs) and Li Ion battery (600 to 800 recharge cycles), and
• Much lower embedded energy due to long life cycle of lamp body, (minimum 10 years) and unbreakable and weatherproof design.

To start here is a comparison between some of the lanterns used by MNRE and other approved lanterns for the Panel Vs Luminary Ratio. In a typical day the lantern discharge is by the wattage of the luminary and the charging is by the Wp rating of the solar panel. The charge vs. discharge ratio of Arundhati Home Light is far superior to others in the market. For example, the charging ratios for existing lanterns vary between 1 and 1.42 (Source: Product Catalogue). On the other hand, the ratio for Arundhati Home Light is far higher, i.e., 3 (see table). If one takes the depth of discharge for the Li-ion batteries in these lamps vis-?-vis the lead-acid ones in others, the ratio increases even further. This chart should be read in conjunction with other factors like efficiency of the lantern, battery DOD, number of charge cycles and Lux levels, etc.

Arundhati 'Solar Home Lanterns' can be assembled by just fastening 9 screws and clipping together 3 pairs of plug and socket joints (see pictures) - thus avoiding complicated soldering and assembly. Since this not only allows quick repair and maintenance but also makes lamp assembly 'idiot-proof' and effortless, the company can supply the lamps in SKD condition for assembly at the village level. It is believed that a trained entrepreneur can make approx Rs 10/- for putting together a lamp and earn Rs 3 to Rs 5/- for recharging each unit from the solar DC generating set (which can also recharge mobile phones in approx 3 hours).

Objectives of Prakruthi Power Solar Lanterns

• Empowerment and demystification of technology to make solar lanterns a cottage industry and facilitate local assembly repair and after sales service
• To add value to millions of people and increase their productivity enable education and livelihood enhancement.

The company can assist organi-sations and NGOs set-up state assembly centres and kiosks (SACKs) from where the finished products can be distributed. An inventory of 2% (as spares) in each SACK will ensure extremely swift turn-around times for repair and/or replacement of malfunctioning parts (5 minutes at the most) - thus ensuring high levels of customer satisfaction and minimal paper-work (for challan/gate-pass/etc).

It also provides OEM back-up for foreign companies for large bulk orders for other campaigns like Lighting Up Africa and Lighting Up Kenya and Light up Malawi initiatives. Another area of concern in rural areas is the charging of various gadgets as different charging platforms are used.

The common platform is 6 V 4.5 AH lead acid battery for solar lanterns (or 12 V) and for mobiles and digital devices a 3.7 V lithium ion platform.

To offer multiple charging options the company has made a common platform for all its products and compatible with a 6 V DC solar panel and 3.7 V mobile charging platform which are interchangeable and complementary. To offer a variety of options for charging, it has introduced:

The products have multiple charging leading to greater flexibility:

• Motor bike mobile charger.
• Bicycle mobile charger.
• Thick pin mobile charger.
• 6/12 V solar PV.
• USB port.

Global Telelinks, manufacturer and exporter of LED solar lighting systems, as designers and consultants specialise in providing urban, rural, industrial and commercial LED lighting solutions. The products are marketed in India and Africa.

(Global Telelinks, Hyderabad. Tel: 040-23350291. Fax: 91-40-23350292. Mobile: 099480-11955, 098483-11955. Email: prakruthipower@gmail.com)