# SolarMath

> Solar calculators & guides


## Posts

- [How Many Solar Panels to Power a House? (2026 Sizing Guide)](https://solarmath.xyz/how-many-solar-panels-to-power-a-house/): Most U.S. homes need 15 to 25 solar panels to cover the bulk of their electricity use. That is the honest short answer — but only a starting point.
- [How Solar Panels Are Priced Per Watt (2025 Breakdown)](https://solarmath.xyz/solar-panel-pricing-per-watt/): The short answer: reduce every quote to one number — cash dollars per watt: total cash price ÷ total watts.
- [What Makes a Roof Good or Bad for Solar?](https://solarmath.xyz/roof-suitability-for-solar/): The short answer: grade your roof on five factors — direction (south = 100%, east or west ≈85%, north ≈65%), pitch (15–45° costs only a few percent), shade (the one factor with no mercy: heavy shade can cost 30–60%), age (under 10–12 years of life left means re-roof first), and material (shingle is the standard case; tile and shake need a specialist).
- [Solar Sales Traps: 9 Tactics and How to Spot Them](https://solarmath.xyz/solar-sales-traps/): The short answer: none of the nine tactics in this guide requires an outright lie — they work by rushing you past the one number or clause that matters.
- [Battery Storage: Do You Actually Need One?](https://solarmath.xyz/solar-battery-storage/): The short answer: a home battery adds $8,000–$15,000 and stores about 13.5 kWh — under half an average home's daily use.
- [Is Solar Worth It in 2026? The Honest Maths](https://solarmath.xyz/is-solar-worth-it-2026/): The short answer: solar is worth it in 2026 for a specific, identifiable set of households, marginal for others, and a poor buy for some.
- [How Net Metering Actually Works (and What Replaced It)](https://solarmath.xyz/how-net-metering-works/): The short answer: under classic net metering, surplus power offsets what you import one-for-one, so every exported kWh is worth the full retail price.

## Pages

- [Disclaimer](https://solarmath.xyz/disclaimer/): Last updated: November 1, 2026.
- [Terms of Use](https://solarmath.xyz/terms-of-use/): Last updated: November 1, 2026.
- [Privacy Policy](https://solarmath.xyz/privacy-policy/): Last updated: November 1, 2026.
- [About](https://solarmath.xyz/about/): SolarMath exists because the most important numbers in a solar decision — your production, your price per watt, your export rate — are usually presented by someone paid when you sign.
- [How SolarMath Calculates](https://solarmath.xyz/methodology/): SolarMath uses the same arithmetic a good installer uses — then shows it to you.
- [Solar Incentives in 2026](https://solarmath.xyz/solar-incentives/): The biggest solar incentive in America ended for homeowners — and a lot of sales material hasn't caught up.
- [Solar Savings Calculator](https://solarmath.xyz/solar-savings-calculator/): Payback tells you when you break even.
- [Panel Count Calculator](https://solarmath.xyz/panel-count-calculator/): Two different questions with two different answers.
- [System Size Calculator](https://solarmath.xyz/system-size-calculator/): Your bill already contains the answer — it just needs converting into kilowatts.
- [Payback Period Calculator](https://solarmath.xyz/payback-calculator/): Not the salesperson's version — yours. Enter your real quote, only the incentives you genuinely qualify for, and your electricity rate.
- [Home](https://solarmath.xyz/): Tell SolarMath your electric bill and your state.


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