Why solar self-consumption matters more than total generation

Generation needs a location model

Roof direction, tilt, shade, climate and system losses affect production. Use PVWatts, PVGIS or the applicable official planning resource instead of a generic kWh-per-kW promise.

Timing creates value

Solar used at the moment it is generated can avoid an imported kWh. Excess generation is exported or curtailed. If the export credit is lower than the import rate, two identical generation totals can have different value because their household demand profiles differ.

Do not count a kWh twice

Self-consumption is the smaller of generation and same-time use. Export is generation minus self-consumption. A kWh cannot both avoid the full import price and earn the export credit.

Keep finance outside the energy result

Installation price, finance, maintenance, degradation, inverter replacement, taxes and incentives belong in a separate cash-flow model with current local evidence.

Use at least a low, central and high self-consumption scenario when household timing is uncertain. This shows whether the decision depends on one optimistic daytime-use assumption and makes future monitoring results easier to compare.