White LED Based  Domestic Lighting System for Rural Nepal

1. Introduction

In Nepal only about 5% of the rural population at present have electric home lighting system. To increase the use of home lighting system more than 25,000 solar PV home lighting systems (SHS) have been installed so far in the various hilly and remote area of the country. As the costs of solar PV home systems (36 Wp module) are still high (in the range of Rs. 25,000 to Rs. 30,000*[1]), SHS is generally unaffordable to the vast majority of the rural households. To address this problem Centre for Renewable Energy (CRE), Bag Bazar, Kathmandu, Nepal has undertaken an adaptive research for development of suitable electric lamps and accessories under RETs-in-Asia Project (Phase II) funded by the Swedish International Development Cooperation Agency (SIDA) and managed by the Asian Institute of Technology (AIT), Bangkok, Thailand.

2. Shortcomings of Lamps used in SHS

Tubular lamps (TL) and compact fluorescent lamps (CFL) presently used in solar home systems of Nepal have the following shortcomings:-

·        Blackening of lamps after some period of use.

·        No certainty of the useful burning life of TL or CFL.

·        Spurious and low cost TL or CFL widely present in the Nepalese markets.

·        Replacement cost of one CFL is sometimes costlier than the purchase amount of kerosene sufficient for operation of the kerosene lamp for 6 months.

·        Electronic components of the ballast of lamp set of SHS often need repair/replacement, which is not easy to achieve at village level.

3.  Need for Development of "TUKIMARA"

 There is a strong need for the design and development of a low cost and reliable lamp set for mass use in village level, which is virtually maintenance free, has a long life cycle, consumes very less power, could be powered/recharged by any renewable source of energy (such as solar, wind, pico-hydro and even human pedal power); and which duly serves the village level lighting needs during the activities of cooking, moving around and reading. 

4. TUKIMARA Lamp

White LED (Light Emitting Diode) based illumination is a potential answer to this problem. CRE has designed and developed some models of White LED lamps called "TUKIMARA" (i.e. Wicked Lamp Killer or more popularly Kerosene Killer, See Photo No. 1 and 2)                       

                                                                        Photo No. 1

                PORTABLE WHITE LED LAMP "TUKIMARA"

                                                                  Photo No. 2

PORTABLE WHITE LED LAMP FOR READING/WRITING PURPOSE

The White LEDs now used by CRE is manufactured by Nichia Corporation, Japan. The ordinary TUKIMARA consists of 3 nos. of White LED; each White LED consumes about 30 to 40 milliamp at 3.6V DC and emits about 5 candela of white light. Therefore 3 nos. of White LEDs used in a TUKIMARA consume a maximum of about 0.5 watt of power, which is a very low figure of power consumption as compared to the power consumption of 10 Watt by a conventional solar DC lamp used in Nepal.

The White LEDs have a rated life of 100,000 hours in laboratory condition; which amounts to 45 years, if used @ 6 hours a day. Even if we achieve 40% of this rated life (i.e. 18 years) in field use conditions; it has obviously a very long useful life. Powering of TUKIMARA lamp sets is done now by 3 nos. of Nickel Cadmium rechargeable batteries (usually D size) each having a capacity of 1,500 milliampere-hour at 1.2V DC. In village condition it has been found that such TUKIMARA lamps need recharging for 2 to 3 hours after every 3 or 4 days of use. The tentative unit cost of such lamp is around

Rs. 1,100 to 1,200 at present.

5.  Advantages of White LED Based Lampsets

·        It creates bright and smoke-free conditions in rural kitchen. That is why women like it very much.

·        It can be easily used as torchlight.

·        There is no danger of fire-outbreak as compared to kerosene lamp. So it is safe even when handled by the children.

·        It has been found quite suitable for use in hotels of rural areas.

·        Recharging of the battery needs to be done only for a period of 2 to 3 hours after every 3 or 4 days of use.

·        Recharging can be easily done by a 1 Wp   solar PV module or by a small bicycle dynamo powered by a tiny pelton water turbine or by pedal power pack operated by human beings.

·        Reliability of the lamp system is very high, as less electronic components are used in the lamp construction.

·        It does not produce radio frequency to interfere with communication equipment or radio.

·        It is polarity protected, so it is hard to make an installation error.

·        It can be placed in abusive environment.

·        It is not easily breakable.

6. Optional Items

A tapping has been provided for connecting a portable transistor radio to TUKIMARA lamp set. One can listen to the radio while cooking in the kitchen or while walking from one village to another either in the daytime or nighttime.

Instead of Nickel Cadmium batteries it is better to use, if available, Nickel Metal Hydride batteries to power TUKIMARA lamp sets. Although it is initially costlier by about 30%; its life cycle is longer. Consequently operating cost per hour of life cycle is less than that of similar Ni-Cd or lead acid or alkaline batteries. Unlike Ni-Cd batteries it has no memory effect. It is generally lighter in weight compared to other similar rechargeable batteries. It gives better performance in cold conditions. Last but not the least it has no toxic chemical; and it is regarded as environmentally friendly.

7. Conclusion

Development of White LED based illumination has obviously brighter potential and a big scope for mass use in low cost home lighting systems in rural Nepal as well as many rural condition of Asia, Africa and Latin America.

For more details, please contact:

Centre for Renewable Energy

Ga-2/717, Bag Bazar

Kathmandu, Nepal

P.O. Box 589

(Near Hotel Ganapati, Bag Bazar)

Phone No. +977-1-248852/351052

e-mail: < cre@ccsl.com.np >

OUR CONCERN IS RENEWABLE ENERGY, ENERGY CONSERVATION AND SUSTAINABLE DEVELOPMENT