Energy solution for rural household in remote cold regions: An innovative photovoltaic-based thermal energy storage system

• An innovative photovoltaic-based thermal energy storage system was proposed. • Variable-power operation control strategy was developed. • System achieves an average indoor temperature of 15.2 °C without consuming grid power. • Solar thermal wall stores 53.25% of solar energy for nighttime heating. Solar photovoltaic systems are crucial to solving the problem of rural energy in remote and cold areas. In the present study, an innovative off-grid photovoltaic energy supply system is proposed, which distinguishes the energy quality differences between electrical energy and thermal energy. Nighttime heating demands are primarily met by a thermal energy storage system, while domestic electricity is flexibly managed using a compact 3.12 kWh battery per building to minimize investment costs. A variable-power technology is introduced to precisely align thermal energy output with solar power generation. Research results show that, during the severe cold season, the proposed system can achieve a photovoltaic power consumption rate of 90.5 % without grid reliance, maintaining an average indoor temperature of 15.2 °C throughout the day and achieving a 100 % solar fraction. The solar thermal wall stores up to 53.25 % of solar energy, indicating its effective management in thermal energy storage and regulation. With a limited number of batteries, the solar energy guarantee rate for household electricity increases from 48.49 % in the heating season to 85.75 % in the non-heating season, thus significantly reducing user energy costs. The integration of energy-grade utilization and variable-power heat exchange technology reduces system construction and operational costs.