Development of solar home system with dual energy storage

Distributed energy generation with energy storage is quite important for high penetration of solar PV energy. A solar home system which generates solar power for self-consumption was studied. The solar home system utilizes a switching-type solar PV (HyPV) which operates in either solar or grid mode automatically without feeding solar power into grid. The solar home system also uses dual energy storage consisting of a battery and an electric water heater which stores PV energy as hot water (thermal storage) when the battery is full. Since thermal storage is much cheaper than battery, the dual energy storage would reduce the total cost of solar home system dramatically. Four HyPV solar home systems were built to run long-term field test. The results show that the specific PV energy generation approximates that of feed-in-tariff PV system. A solar PV energy production cost analysis shows that the HyPV solar home system with dual storage is economic if it was used to replace partial energy demand which is paid at higher grid electricity price. This verifies the possibility of grid parity for a solar PV system with energy storage.