Large-scale quantification of the future self-covered heat demand using a nationwide residential building database

Electrifying residential heat supply with rooftop photovoltaics (PV) and air-source heat pumps is essential for decarbonizing the German building stock. The potential of these technologies depends on factors such as building properties, rooftop area, weather, and resident behavior. Using a building database and statistical data, we analyzed how much of the residential heat demand in Germany could be independently met by homeowners using PV, heat pumps, batteries, and thermal energy storage. Our energy system model, based on detailed bottom-up building simulations, indicates that 35.2 % of the average annual heat demand can be covered by on-site supply. Grid savings are most significant in well-refurbished single-family and terraced houses, reaching 35 % annually. During cold periods, these houses achieve grid savings of 52%–70%, while in warm periods, they feed 155%–317% surplus electricity back into the grid. Understanding the electricity consumption and grid contributions of solar-assisted heat pumps is critical for accurate grid load forecasting and planning local grid expansions. This knowledge also supports homeowners and policymakers in evaluating the advantages and limitations of these systems, informing subsidy programs and regional energy strategies.