1. Start with heat demand
Assess heat losses, emitters, hot water and planned insulation. Request heating capacity and estimated electricity use under the building’s conditions. A heat pump uses electricity and environmental heat; performance varies with temperatures and operation. Floor area or a data-sheet COP alone cannot calculate the whole year.
2. Align the profiles
Request monthly solar generation and electricity demand, then relevant hourly profiles. Separate direct use, storage, feed-in and grid purchases. Balanced annual kWh do not mean winter heating is covered. Compare the current home and use after renovation without borrowing another installation’s coverage percentage.
3. Check available controls
Confirm compatible models, interfaces and functions across the heat pump, inverter and energy manager. Ask what controls change and how comfort, temperature and warranty limits are respected. A domestic hot-water tank and heating buffer serve different needs. Scheduling extra consumption is not a saving if the energy is unnecessary.
4. Assess storage and backup separately
Compare no-battery and battery options with explicit usable capacity, power, losses and reserve. A battery shifts available energy; it creates neither missing sunshine nor automatic seasonal storage. For backup, specify circuits, heat-pump starting requirements, power and switching. A battery or hybrid inverter alone does not guarantee heating during an outage.
5. Coordinate quotations and handover
Separate heating, PV, controls, storage, adaptations and additional work. Define contractor coordination, tests, documented settings and service contact. Calculate operating costs using tariffs, maintenance and replacement; check each item’s grants and timing. After handover, compare generation and consumption with the assumptions rather than a general self-sufficiency promise.