Verification of consumer´s benefits for different area ratio of PV array and solar thermal water heater considering regional characteristics

Along with the advancement in mass introduction of solar photovoltaic (PV) systems to residential sector, power supply and demand balance adjustment becomes difficult due to increased reverse power flow to the power grid. As a countermeasure to this problem, we focused on the combination of the PV array and the solar thermal water heater (STWH). Thus, a part of the solar energy that consumers had flown to the power grid as the reverse power flow from the PV will be utilized in the form of heat. In this paper, considering that the performance of PV and STWH are dependent on weather conditions, we simulated the operations of consumer´s equipments while changing the area ratio of PV and STWH on the roof in the 10 regions of Japan with different weather conditions. As a result, the area ratio, which the forward and reverse power flow is the smallest, was obtained. In addition, we performed the simulations respect to economic efficiency of the STWH in six scenarios at two power buying prices rate and the three stages of power selling prices (power selling prices of current and expected in future). We could confirm an improvement in economic efficiency through the introduction of the STWH along with the reduction of the power selling price.