Inputs that make a solar payback estimate useful
Understand yield, self-consumption and export value before calculating payback.
Estimate generation locally
Annual solar yield depends on location, roof direction, tilt, shading and equipment. PVGIS is a useful independent starting point for European locations.
Value generation correctly
Self-consumed electricity usually offsets the retail import price. Exported electricity should be valued using the actual export or compensation arrangement.
Know what simple payback excludes
A simple payback estimate does not automatically include financing, maintenance, inverter replacement, degradation or future tariff changes. Use it as a comparison tool, not a guaranteed return.