ENVIRONMENTALLY FRIENDLY RENEWABLE ENERGY RESOURCE FOR RURAL ELECTRIFICATION IN ETHIOPIA:
PHOTOVOLTAIC POWER

Amare Hadgu, M.Sc. (EE), M.Sc. (EIMT),
P.O.Box 34281, Addis Ababa

ABSTRACT

Ethiopia is one of the developing countries that mainly depend upon traditional energy sources such as fuel wood and other biomass fuels. Modern forms of energy mainly petroleum products and electricity are available, but only cover narrow section of the society. The supply of electricity based on the existing installed capacity, which is about 400 MW, serves about 5% of the population. Since about 85% of the population lives in scattered villages all over the country, expansion of the electricity power grid to those areas is extremely difficult and expensive.

Photovoltaic is an ideal energy source for rural electrification in Ethiopia for the following reasons: (1) there is plentiful solar energy resource with a yearly average daily solar radiation of 5.4 Kwh/m2 ; (2) there is close match between the small, modular nature of photovoltaic power and the Ethiopian remote villages; and (3) there is acute shortage of electricity generation capacity in Ethiopia. On top of this, it is highly expensive to stretch the distribution grid to isolated houses in rural areas. It is cost effective to use photovoltaic instead of connecting scattered rural houses to the grid.

This project was supported by the Ethiopian Science and Technology Commission under the 5th cycle (1996/97) Local Research Grant. The project aims to study the performance of a solar battery and a regulator in the photovoltaic power system (BOS) and to identify the proper standards of a solar battery and a regulator for the rural household electrification. The loads assumed are lighting, radio cassette player and TV/VCR. The project has employed different methodologies such as library research, site visits and experiments so as to select the proper storage battery and regulator for rural electrification in Ethiopia.

The car battery manufactured locally by Addis Car Battery Factory at Nefas Silk, BP Solar Battery, and a minicharge regulator were used for the experiment on the performances of storage batteries and regulator in the photovoltaic balance of systems.

From the experiment carried out, the array open voltage, array operating voltage, array current, battery discharge voltage and battery discharge current of the two batteries were in the same range. The comparison of the two batteries was done for about three months and thus, it could not be taken for granted that their performance is similar for prolonged years.

Even though there are different technologies to manufacture different types of batteries, the lead acid battery is cost effective for rural electrification which can be made available as shallow as well as deep cycling storage battery. In the photovoltaic power system, the discharge current is not high but it is relatively for prolonged time. Hence, the storage battery for photovoltaic for rural electrification must be deep cycled which is designed for longer life.

The ordinary car battery used in the research experiment will not last longer than 2-3 years. Whereas, the solar battery of the BP solar type can last for about 8-10 years. The locally manufactured car battery can be used as it is. Its drawback is the short life span. The design of the locally manufactured battery can be modified so as to enable it to qualify better as battery storage of photovoltaic. Considering cost and operational issues, a sophisticated charge regulator may not be necessary for rural electrification.. However, it will be a grave mistake not to incorporate a charge regulator to stand-alone PV power supply. The minicharge regulator used in the experiment properly functioned in connecting and disconnecting the circuit in the needed arrangement. A charge regulator has been designed which needs further developmental research work to make it economically and technically viable.

Note: The final report is available at the Central Technical Library of the ESTC.

(Report 1997

 

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