No sign-up · no phone number
Free Solar Calculators & Decision Tools
Size a system, test roof fit, estimate cost and financing, plan battery backup and check federal eligibility. Every calculator shows the assumptions behind its result.
Cost · size · financing
Solar Cost & Payback Calculator
Start with your state and bill. Estimate panel count, system size, cost range, production, cash payback or loan payment with visible assumptions.
Panel count · output · roof fit
How Many Solar Panels Do I Need?
Convert monthly kWh into panel count and DC system size. See output per panel plus a first-pass roof-space check.
Storage · critical loads · outage
Home Battery Backup Calculator
Choose critical appliances and runtime to estimate nominal battery kWh and minimum continuous output.
Federal eligibility · placed-in-service year
Solar Tax Credit Calculator
Check historical federal residential eligibility and the current rule for new property placed in service after December 31, 2025.
Evidence labels, not fake precision
Observed installation cost comes from Berkeley Lab Tracking the Sun. Residential rates come from EIA State Electricity Profiles 2024. Production and backup results are modeled estimates from explicit assumptions. Federal eligibility follows current IRS guidance. A calculator result is not an installer quote, engineering design, utility approval or tax advice.