Design and Analysis of Solar Energy Mini-Grid for Rural Electrification

Abstract

Electric power is a key driver of economic growth and prosperity. But access to electricity still remains a distant dream for majority of the population living in the remote and arid areas of developing countries mostly sub-Saharan Africa. With the growing demand for safe and reliable energy, solar as a source of energy remains the least utilized energy source in the Kenyan economy and yet one of the safest forms of energy. Solar photovoltaic (PV) systems have shown their potential in rural electrification projects around the world. A solar based mini-grid is a solar PV (photovoltaic) plant with a localized distribution network to a unit village, or a cluster of villages, providing alternating current (AC). Basically it consists of solar PV modules of a certain capacity, solar inverters for converting the D.C power to AC power, housing for the battery bank and plant control systems. In areas where there is no grid connection or where diesel generation is the main power source, PV plants are able to generate electricity efficiently and relatively cheap. This paper was aimed at developing a standard procedure for the design and analysis of a mini-grid connected solar PV systems using PV modules connected in an array field. The standard procedure developed was validated in the design of a 20 kVA mini-grid-connected solar PV system for Nanyuki town in Laikipia County, Kenya. The analysis and evaluation of the load capacity requirements for the solar mini-grid were done. Data collected from SWERA were compared with the local load requirements. Optimization of the load versus production capacity of the solar system was carried out. The results showed that a mini-grid system of 20 kVA might be developed at a capital cost of US$ 56,000 to cater for 8400 households including a school and dispensary. Analyses of the simulation results show that the project when implemented will supply about 61 KW·h electricity per day or 22.2 MWh annually, which is about 15% of Nanyuki’s annual electricity consumption. The project also stands the chance of saving about 200 tonnes of CO2 which will have been emitted by a crude oil fired thermal power plant generating the same amount of electricity. At the prevailing tariff conditions in the country, this project can be considered as financially viable with feed-in tariff scheme or other incentives such as grants/capital subsidies when applied. However, the other non-financial benefits like the greenhouse gas emissions savings can, in the long run, help mitigate the adverse effects of the climate change problem plaguing the entire earth.