Impact of electricity tariff structures on the economic and flexibility potential of residential heat pumps − evidence from Jeju Island

Residential heating electrification requires reliable operation and economically viable electricity tariffs. This study evaluates the field performance and tariff implications of R32 air-source heat pumps integrated with thermal energy storage (ASHP–TES) in five occupied detached houses on Jeju Island, South Korea. Measured data were used to assess system operation, hourly electricity consumption and thermal demand, and operating costs under alternative tariff structures. Temperature-based TES control supported space heating and domestic hot water supply. During 11:00–15:00, the heat pumps consumed 1,722 kWh, representing a mean household-level share of 13.4% of total heat-pump electricity consumption. Hourly profiles characterized electricity use relative to thermal demand, while calculated TES headroom indicated theoretical additional thermal storage capacity under observed conditions. Applying alternative tariffs to measured electricity consumption revealed substantial differences in calculated costs. At higher consumption levels, the general-service tariff was less costly than the residential progressive tariff under the evaluated billing scenarios. These findings provide field-based evidence of residential ASHP–TES operation and highlight the importance of tariff structures for the economic feasibility of heating electrification.