Optimization and techno-economic study of a PV Battery system for a vacation home in Sweden

Abstract: Currently, Sälen area in Sweden is finding issues in the power grid due to an irregular load profile with high peak power demand and an infrastructure that is becoming undersized. Distributed PV-battery systems are considered a possible solution to solve this problem.A PV-battery system for a typical vacation home in this town is designed and optimized to give the best economical solution to the homeowner. Then, a techno-economic evaluation of the system is performed. A photovoltaic system and an only grid connected system are also simulated and compared. Finally, a sensitivity analysis is performed on different simulation inputs.HOMER Grid software is used to simulate and size the system. Firstly, a pre-sized system is modelled using average or typical market prices and component characteristics. Afterwards, real market components that fit into the pre-sized model are modelled to get a real system design. The optimized design includes a PV system of 13 kW, a BYD lithium ion battery of 5.1 kWh capacity and a Sungrow hybrid inverter of 10 kW.The economic evaluation of the system indicates that, with current market prices and subsidies, the optimized system is the most economical solution for the homeowner compared to the other systems. In the sensitivity analysis, a significant risk for the profitability of the system is found on the compensation from selling electricity to the grid.The technical evaluation of the system indicates that the battery provides a significant peak-shaving effect that can benefit the power grid. However, large solar energy sales to the grid with high power peaks that could cause instability issues are observed.