Daytime Operation of Heat-Pump Water Heater for Mitigating Voltage Rise Due to High Penetration of Residential Photovoltaic Power Generation Systems

The high penetration photovoltaic power generation systems (PVS) may cause the voltage rise of a power distribution system. As one of the measures, we focus on the daytime operation of heat pump water heater (HPWH). This study introduces the brief idea for scheduling the daytime operation so that the total electricity demand change of a number of HP follows the insolation change in a day. Then, this study demonstrates the effect of daytime operation using the electricity and hot-water demand observed in 10 households for a year. As the result, when the daytime operation is applied to HPWH in a household with PVS, the voltage rise can be mitigated without causing the under voltage condition due to the unnecessary daytime operation.