Techno-economic evaluation of a grid-connected residential rooftop photovoltaic system with battery energy storage system: a Romanian case study

Solar energy is one of the most valuable renewable energy sources and, as the technologies advances, is expected to be an increasingly viable alternative to conventional energy sources. Battery energy storage systems represent a solution for solving the problem of solar resource intermittency and, at the same time, may decrease the electricity bill by supplementing the electricity self-consumption of residences. This paper is aiming to evaluate from a technical and economic point of view the viability of a grid-connected rooftop solar photovoltaic system combined with several battery energy storage systems for a residence in Romania. The results obtained indicated that mainly due to current costs of energy storage and photovoltaics, the installation of a battery energy storage system together with a photovoltaic system could be profitable only when upfront subsidies are granted.