Optimum Battery Capacity for a Rooftop PV Solar System

Among all renewable sources of energy, solar energy is a promising and freely available energy source for managing long term issues in the energy crisis. Continuous advancements of PV and battery technologies have made battery connected PV systems an attractive prospect for residential energy consumers. This paper focuses on an optimum way of implementing battery connected PV Solar System as a solution for the energy crisis of Sri Lanka and to achieve technical and economic benefits towards both consumer and supply authority. Shifting the daytime excess solar energy(kWh), to be consumed during peak hours or supplying energy(kWh) to the grid during peak hours is mainly focused in this paper. The optimum battery capacity and the number of solar panels are selected using different controllable grid discharge methods, measured Sri Lankan residential consumption data, current Time of Use tariff and available domestic electricity plans. Constant grid discharge method is beneficial for consumers with low domestic demands (200300kWh) while the most beneficial method for consumers with high energy demands (300kWh to 400kWh, 400kWh to 600kWh, 600kWh to 800kWh), is the peak reduction method.