Make solar add up.
A simple annual estimate using your own assumptions. Start with a quote and a generation estimate for your roof.
Annual net benefit
How the estimate works
Annual benefit = electricity used at home × purchase price + electricity exported × export price − annual running allowance. Simple payback = installed cost ÷ annual benefit.
This is a solar-only illustration. It excludes finance, taxes, grants, degradation, future tariff changes and equipment replacement. Self-use is the share of generated electricity used at home; it must not exceed your actual demand. A battery needs a separate calculation including losses and replacement.
Start with installed cost and a roof forecast
Enter the full price of the solar-only installation, including the work needed to put it into service. Use annual generation in kWh from a roof-specific forecast, not the panel rating in kWp. Keep a battery outside this calculation so its cost and benefit can be assessed separately.
Estimate direct use from your daily pattern
Direct use is the share of solar generation consumed at home as it arrives. It is not the share of your total household demand supplied by solar. Try a lower and a higher value that fit your routine, and compare the result. A year with 4,500 kWh generated and 40% direct use allocates 1,800 kWh to the home.
Read the result as a comparison
The annual benefit combines avoided electricity purchases and export income, then subtracts the running allowance. Simple payback divides the installation cost by that benefit. Change one input at a time to see its effect. Fixed charges that remain on your bill are not avoided by each solar kilowatt-hour.