Evaluation of energy and economy of battery system installation in residential PV system after FIT expiration

Abstract

To evaluate the economy of installing a storage battery system to a post-FIT photovoltaic power system for residential use, we conducted a power transmission simulation and calculated the annual economic effect in Hamamatsu, Japan. The simulation was performed using the battery capacity, connection method, charge/discharge control method, and working time of heat pump water heater (HPWH) as parameters. As a result, it was found that the initial cost of the battery system cannot be recovered under any conditions. The initial cost can be recovered if the cost drops to 35% of the current level, the battery life reaches 28 years, or the power price increases to 186% of the current level. By shifting the working time of HPWH to daytime without installing a battery system, it is possible to reduce 3700 yen annually, which is effective for homes that have installed more than 5 kW PV system with relatively high irradiation areas.