Design of a Grid Connected Photovoltaic System for Enhancement of Electrical Power Supply in Kenya: A Case Study of Nairobi Embakasi Suburb

Abstract

The demand for electrical energy in Kenya has been on the increase since the country got its independence that brought freedom in 1963. This increase in power consumption has been due to population increase and national economic growth. The increase in demand without a matching increase in generation has resulted in perennial electrical power shortfall necessitating the Kenyan Electricity Supply Industry (ESI) to resort to expensive fossil fuels for electrical power generation. This electricity shortfall has affected industrial growth and envisaged markets expansion in the country. If the problem is not addressed, in good time, future national growth projections may not be met. Power generation in Kenya is mainly from hydro, geothermal, diesel, gas and to a lesser extent, wind. Kenya has a geographical advantage by virtue of being located at the equator and between the tropics where the solar cycles can be accurately predicted. This research therefore, sought to explore available methods so as to develop a renewable method to mitigate electrical power generation shortage in the country using grid-connected solar photovoltaic (PV) electricity generation in urban areas. Data for solar insolation and domestic load from the case study suburb (Embakasi Nyayo Estate) was collected and then matched so as to design a typical solar photovoltaic system. Data collected show that the case study suburb receives a monthly average solar insolation of 5.2 kWh/m2/day for most part of the year. In this area and time solar irradiance of 1.25kW/m2 is a common occurrence between 11.00 AM and 1 PM. The same data also reveal that one three bed roomed master en-suite apartment building at the case study, requires about 6.13 kWh per day with a morning peak of 1.5 kW and an evening peak of 2.5 kW, while a block of eight apartments has a daily energy demand of 48.8 kWh. Both statistical and solar PV system design software were used to develop the plant. The design was done with a block peak power demand consideration of 12.5 kW so there is surplus solar PV electricity generation during off peak that could be injected into the grid. A battery storage capacity of 3600 Ah was provided that could supply the evening peak and also provide 1 days of autonomy. The researcher has produced a complete typical solar PV electricity generation system design suitable for the case study suburb. Further the solar photovoltaic electricity generation potential for the entire case study suburb was aggregated so as to quantify the amount of enhancement resulting from the solar PV systems implementation. The case study suburb aggregated peak solar photovoltaic electricity generation is estimated at 3.12 MW. Design results show that one block of eight apartments will be capable of generating 19,402 kWh annually making the total energy generated in the 480 block suburb to be 9,312,960 kWh annually.