Wattcrunch is a free, independent set of solar tools for US homeowners. We exist to answer the questions every household asks before going solar — how big a system do I need, what will it cost, how much will I save, and how long until it pays for itself — with numbers you can actually trust, and without a sales pitch attached.
Why we built it
The internet is full of solar calculators, but most are lead-generation funnels: they ask for your phone number, hand your details to installers, and quietly inflate the savings to push a sale. Worse, many are simply out of date. When the federal residential solar tax credit ended on December 31, 2025, the majority of online calculators kept applying a 30% credit that no longer exists — overstating savings by thousands of dollars. We decided to build the opposite: tools that are accurate, transparent about their assumptions, and free of dark patterns.
How our numbers are calculated
Every figure on Wattcrunch comes from a documented, unit-tested formula — not a black box. Production estimates use the National Renewable Energy Laboratory's PVWatts model, the same engine professional installers rely on, tied to your exact latitude and longitude. Financial projections account for module degradation, utility rate escalation, net-metering policy, and the current federal and state tax landscape. Our incentive database is curated from DSIRE and public utility tariffs, and every record shows when it was last verified.
Our commitment to accuracy
Tax and incentive policy changes, and we change with it. The 2026 expiration of the Section 25D homeowner credit is reflected throughout our calculators by default, while still letting you model systems placed in service in 2025 or earlier. When the rules shift again, our tools will too. We would rather show you a smaller, honest number than a flattering, wrong one.
What we don't do
We are a planning resource, not an installer, lender, or tax advisor. We never sell your personal information, and our calculators work without an email address. For a binding quote, confirm your numbers with a licensed local installer; for tax questions, consult a professional.
Ready to run your own numbers? Start with the System Size Calculator, estimate your savings with the Solar Savings Calculator, or find what you qualify for in the Incentive Finder. Questions? Contact us.