How this calculation works
Annual generation = panel kW × equivalent sun hours × 365 × performance. Value self-used generation at your avoided tariff and exported generation at the entered credit. Deduct annual maintenance. Simple payback is capex divided by positive annual net savings; NPV discounts each year’s constant net savings and subtracts capex.
A worked example
5 kW × 4 full-sun hours × 365 × 80% produces 5 840 kWh per year before applying self-consumption and export assumptions.
Assumptions & limitations
- This is an energy-cost scenario, not an installation design or guaranteed saving. Fixed electricity charges remain payable. Only enter an export credit if your connection and contract allow it.
- Tariffs and output stay constant; degradation, financing, major replacements beyond your allowance, battery dispatch, load-shedding value and tax incentives are excluded.
