How to Use This Calculator
Enter your average monthly electricity bill, your state, and your roof type. The calculator estimates your system size, installation cost, annual savings, payback period, and 25-year net savings — all based on your state’s electricity rate and solar resource data.
Note on the federal tax credit: The 30% residential solar tax credit (Section 25D) was eliminated for systems installed after December 31, 2025, by the One Big Beautiful Bill Act. This calculator reflects current law — no federal credit is applied. If you installed solar in 2025 or earlier, see our federal solar tax credit guide to claim the credit on your 2025 tax return.
Solar Cost & Savings Calculator
Enter your details below to get a free estimate — no signup required.
How the Calculator Works
The calculator uses your monthly bill and state electricity rate to estimate your household’s monthly kilowatt-hour (kWh) usage. From there, it uses your state’s average peak sun hours to size the system needed to offset roughly 85% of your electricity use — a realistic target that accounts for shading, seasonal variation, and system efficiency losses.
System cost is estimated at $3.00 per watt installed, which reflects the national average for a fully installed residential system in 2026 (panels, inverter, mounting hardware, labor, and permitting). Flat roofs add ~5% to labor costs; steep roofs add ~10%. See our solar panel cost guide for a full breakdown by state and system size.
Annual savings are estimated as 85% of your annual electricity bill, assuming the solar system offsets that portion of your consumption. The payback period is your system cost divided by annual savings. The 25-year net savings figure subtracts your system cost from your cumulative savings over a standard 25-year panel warranty period.
What Affects Your Actual Quote
Roof condition and complexity. A roof that needs repair before solar installation adds cost not captured here. Most installers won’t put panels on a roof with less than 10 years of life remaining. Labor costs rise significantly with pitch, material type (slate and tile cost more than asphalt shingle), and roof access.
Shading. Trees, chimneys, dormers, and neighboring buildings reduce energy production. A heavily shaded roof can cut output by 20–40%, which lengthens your real payback period considerably. A professional site assessment accounts for this; this calculator cannot.
Panel brand and inverter type. Premium panels (REC, Panasonic, SunPower) cost 15–25% more than standard tier-1 panels but carry higher efficiency and better warranty terms. Microinverters (Enphase) cost more than string inverters but perform better on partially shaded roofs. See our best solar companies guide for what each installer typically uses.
Net metering policy. This calculator assumes you can sell excess generation back to your utility at approximately retail rate. In states where net metering has been reduced — notably California (NEM 3.0) and Nevada — the value of solar exports is lower, which extends real-world payback periods beyond this estimate. The state notes shown after calculating reflect the most significant policy caveats.
Battery storage. Adding a home battery (Tesla Powerwall 3, Enphase IQ Battery 5P, or similar) adds $10,000–$18,000 to system cost. Battery storage is not included in this estimate. It makes sense primarily in areas with frequent outages, time-of-use utility rates, or poor net metering.
Frequently Asked Questions
Is there still a federal tax credit for solar in 2026?
No. The 30% residential solar tax credit (Section 25D) was eliminated for systems placed in service after December 31, 2025. If you installed solar in 2025 or earlier, you can still claim the credit on your 2025 tax return. See our federal solar tax credit guide for details.
How accurate is this estimate?
It’s a ballpark — useful for evaluating whether solar makes financial sense before spending time getting quotes. Real quotes from installers will differ based on your actual roof, shading, local labor market, and the specific equipment used. For most homeowners, real quotes come in within ±15–20% of this estimate.
My monthly bill varies a lot by season — what should I enter?
Use your average monthly bill across the full year, not your summer or winter peak. You can calculate this by dividing your annual electricity spend by 12. Your utility’s online account portal usually shows your 12-month average.
Does the calculator account for electricity rate increases?
No — it uses your current rate as a fixed number. In practice, electricity rates have risen ~3–4% per year nationally over the last decade. If rates continue rising, your real payback period will be shorter than this estimate, and your 25-year savings will be higher. This makes the calculator’s output a conservative estimate for most homeowners.
Get Free Quotes →
The difference between a competitive installer quote and an overpriced one can easily be $5,000–$8,000 on a typical system. Getting multiple quotes is the single best thing you can do to improve your solar ROI.
We connect you with pre-vetted installers in your area. No obligation, no spam. See our best solar companies guide for what to look for when comparing quotes.
Calculator last updated: May 2026. Electricity rate data sourced from U.S. EIA (Electric Power Monthly, April 2026). Peak sun hour data sourced from NREL’s National Solar Radiation Database. System cost estimate based on Lawrence Berkeley National Laboratory “Tracking the Sun” report and EnergySage 2025 Solar Market Report.