How We Calculate Solar Costs
By Shannon Midthun · LTR Advisory LLC · Last updated June 2026
Built for 2026. Our estimates reflect what a homeowner actually pays today — after the 30% federal residential solar tax credit ended on December 31, 2025. We don't apply a credit that no longer exists.
Our data sources
- Installed price per watt — based on national and state cost benchmarks from the National Renewable Energy Laboratory (NREL), adjusted for observed 2026 market pricing.
- Electricity rates — state-level residential averages from the U.S. Energy Information Administration (EIA).
- Sunlight & production — regional peak-sun-hour data used to estimate a system's annual output.
How the estimate works
- Your state sets the local cost-per-watt and average electricity rate.
- Your monthly bill estimates your usage and the system size needed to offset it.
- Your roof's sun exposure adjusts expected production.
- We calculate system cost, estimated annual savings, payback period, and 25-year net savings — with no federal tax credit applied. State, utility, and local incentives may still reduce your cost; we note those on our state pages.
What we don't do
We don't sell solar panels, and we're not owned by an installer. Our estimates are general information to help you plan — not a quote or tax advice. Always confirm specifics with a licensed installer and a tax professional before you buy.
More about who's behind this and why: About Solar Cost Advisor.
