Electricity demand load curves of all-electric houses and measures for effective use of solar power generation

• Electricity demand data from the Home Energy Management System were analyzed. • The average self-consumption rate of solar power generation was 36% • Cluster analysis was used to examine the differences between house characteristics. • Changing battery operation can shift the demand to 1100 kWh/y during the daytime. • Operating a water heater during the daytime can shift the demand by 1200 kWh/y. The utilization of renewable energy is as important as saving energy, and the prevention of solar power curtailment is crucial to realize a carbon neutral society. Previous studies have not sufficiently examined the potential for adjustment by considering the actual power consumption and housing characteristics. This study explores the possibility of increasing the self-consumption of solar power generation by shifting the timing of the electricity demand of all-electric houses from night to day. To accomplish this, Home Energy Management System data were used to generate electricity demand curves. The average self-consumption rate was 36%, and all the target houses had the potential to reduce the surplus electricity sold. Since demand curves depend on the lifestyle of the occupants and lifestyle influences the possibility of improvement, the difference in demand between houses was considered via cluster analysis. The cluster analysis clarified the proportion of houses for which the measures implemented to increase self-consumption were effective. In most houses, electricity and hot water were stored during the nighttime; however, operating a storage battery and a heat pump water heater generated daytime demands of approximately 1100 and 1200 kWh/year, respectively. Additionally, the capacities of the storage batteries of the target houses were 5.6–6.5 kWh; however, the daily amount charged relative to the capacity was small to prepare for outages. The capacity can be increased to reduce the power purchased and sold. The findings inform the development of effective decarbonization strategies and help mitigate climate change by preventing output curtailment.