Investigation of electric grid unavailability and back-feeding on the economic viability of a grid-connected rooftop solar photovoltaic system integrated with battery energy storage

ABSTRACT The generation of energy with renewable energy resources is necessary to achieve the sustainable development goal of clean and affordable energy. This study investigates the effect of an unreliable electric grid on solar photovoltaic energy integration. Also, it assesses the effect of back-feeding energy to the electric grid on the economic viability of the system. The case study location is Eagle Square in the Federal Capital Territory Abuja of Nigeria. A detailed analysis of technical, economic and environmental aspects of the solar photovoltaic system is discussed. The study considered electric grid islanding of the mini grid system due to power outage on the main electric grid with unavailability ranging from 0.8% to 67% annually. PVSyst was used to integrate the building 3D model with solar photovoltaic panels and run the energy simulation. The best performing system had the ability to back-feed energy to the grid with a 0.8% grid unavailability, the lifetime energy generation was 143,129 MWh at a performance ratio of 0.773. The project had a payback period of 5.5 years with an LCOE of 0.118 $/kWh, it had a total carbon dioxide emission saving of 46,155 tons for the 25 years project lifetime.