Free, instant, no signup. Solve for payback period, system size, battery storage, and 25-year savings — with real ingredient-level math, not generic "solar pays for itself in 7 years" handwaving.
How many years until your panels pay for themselves — with inflation, current incentives, and the real math.
What size system (in kW) actually covers your bill, accounting for sun hours, EV plans, and roof efficiency.
How much battery you need for backup hours, with specific Powerwall, Enphase, and Franklin recommendations.
The 30% federal credit ended after 2025. See whether your install still qualifies, what state credits apply, and any carryforward.
How much extra solar to power your EV — vs grid charging, vs gas. Preset models for Tesla, Rivian, Lightning, Ioniq.
Should you finance or pay cash? 25-year comparison with monthly cash flow, total interest, and dealer-fee analysis.
For cabins, tiny homes, RVs, full off-grid living. Sized for winter worst case + battery autonomy days.
Most solar calculators online are lead-capture forms in disguise. They ask you for your phone number, send your data to 6 installers, and never actually show you the math.
SolarSavingsMath does the opposite: real calculators, real numbers, no signup, no lead capture. If you eventually want quotes from installers, we'll point you to honest options. But first, you should know the math.
Every formula on this site is open. We cite NREL, EIA, and IRS as primary sources. If a number looks wrong, tell us and we'll fix it.