Solar Calculators
Free tools to estimate the solar system size you need and how long it takes to pay for itself. Sources and formulas are shown on each page.
Step 1
Solar System Size Calculator
Enter your yearly electricity use and get an estimated system size in kW, a panel count and a rough price. Every default is sourced and can be changed.
Open calculator → Step 2Solar Payback and ROI Calculator
Estimate how many years a home solar system takes to pay for itself, and its return over 25 years, from your price, electric rate and your utility's export rules.
Open calculator →Start with system size. It passes your result to the payback calculator. Both give estimates from the figures you enter, not quotes. See our methodology.