FAQ Production and yield of solar panels

kWp expresses module rated power under standard test conditions. kWh expresses energy produced or consumed over a period. Annual output per kWp depends on location, orientation, shading and losses and should be simulated for the roof concerned.

For example, an assumption of 1 100 kWh per kWp per year gives 8 800 kWh for 8 kWp. This is not a local guarantee. Have monthly output, shading and losses simulated. Annual output above annual consumption does not mean demand is met every hour.

Compare the same period, actual weather and simulation assumptions. Check inverter availability, meter data, shading and alerts. No universal threshold explains every discrepancy. If it persists or comes with an alarm, request a documented installer diagnosis without working on electrical equipment yourself.

PR compares final specific yield Yf with reference yield Yr: PR = Yf / Yr. Yf is delivered energy divided by rated power; Yr is irradiation in the module plane divided by reference irradiance of 1 kW/m². Use the same period and a defined measurement boundary. PR is not cell conversion efficiency or the share of radiation converted into electricity.

Degradation depends on the model, environment and installation. A warranty may specify an initial drop followed by an annual limit; it is not a guaranteed measurement of future roof output. Compare the guaranteed residual-power schedule and exclusions, then track output adjusted for weather and losses.

Yes, but day length, clouds, shading and snow change output. Heating demand may rise when solar availability is lower. Request a monthly profile and, for a battery or heat pump, an hourly simulation. A home battery does not transfer summer surplus into winter.