Calculator Methodology

The calculator uses simplified UK solar assumptions to estimate annual electricity usage, solar system size, generation, savings, export income, payback period, and CO2 savings.

Core assumptions

It uses a default electricity rate of 27p/kWh, export rate of 8p/kWh, regional solar yield assumptions between 800 and 950 kWh/kWp/year, roof direction multipliers, shading multipliers, and self-consumption estimates.

Important limitations

The calculator is not a quote. A proper installer survey is needed to confirm roof suitability, system size, products, installation cost, and expected performance.