Donaldson R F Solar Panel Savings Calculator
See how much electricity a solar system could produce for your home, what it could save you every year, and when it pays for itself.
Your electricity
The solar system
Cost
How the estimate is calculated
Yearly production = system size (kW) × peak sun hours per day × 365 × system efficiency. “Peak sun hours” are hours of full-strength sunshine — about 3 in cloudy northern regions and 6 or more in deserts; check a solar map for your address. Efficiency (typically 75–85%) allows for inverter, wiring, temperature and dirt losses. Each year production falls by the degradation rate and your electricity price rises by the increase you set. The part of the solar power you use directly avoids buying electricity at your full price; the rest is exported and paid at the export rate. Payback is when your cumulative savings, minus maintenance, overtake the cost after incentives. The result is an estimate: real output depends on roof angle, shading, weather and how your household uses power, and prices, tariffs and incentives vary by country and change over time. Get quotes from installers and a site-specific production estimate before deciding.