Smarter energy.Clearer decisions.

Use a calculator to test which assumptions matter before comparing proposals. Start with 12 months of electricity use, an itemized installation quote, and your utility's import and export rates. Change one input at a time. A site inspection and equipment-specific design are still needed to estimate production at your home.

All calculators are free to use without registration or an email address. Optional product links may earn a commission where disclosed. Calculator results are planning estimates and do not establish savings, financing terms, or incentive eligibility.

The stored electricity-rate table uses June 2026 data. It does not update automatically every month. Solar models use simplified annual-average sunlight inputs, not a roof-specific hourly PVWatts simulation. There is no validated site-wide accuracy percentage. Replace defaults with your bills, local tariff, and equipment specifications; the methodology page explains the assumptions.

The solar calculators use zero for the federal Section 25D credit on new 2026 installations. The IRS states that the credit is unavailable for property placed in service after December 31, 2025. Check the linked IRS guidance on our methodology page for prior-year claims and your state or utility administrator for other incentives.

First calculate your gasoline cost and grid charging cost for the same annual mileage. Then value solar used for charging against the electricity it replaces, allowing for any export credit you give up. Do not count the same solar kWh as both household bill savings and free EV fuel. Include installation and vehicle costs, financing, losses, and maintenance before interpreting operating savings as a financial benefit.