Solar Savings & Payback Period Calculator
Enter your own numbers — not a national average — to estimate how long a solar system would take to pay for itself and what it could save you over 20 years. This tool assumes $0 federal tax credit by default, reflecting the Section 25D repeal that took effect January 1, 2026. Seewhat changed and why.
Your estimate
- Estimated annual production
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- Estimated annual savings
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- Net cost after incentive
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- Simple payback period
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- Estimated 20-year net savings
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Assumes a system derate factor of 0.8 (typical real-world losses from inverter efficiency, temperature, soiling, and wiring) and that your utility credits exported solar at close to your full retail rate. It does not account for future electricity rate changes, panel output degradation, or financing costs — treat this as a starting point, not a quote.
Frequently asked questions
Does this calculator include the federal tax credit?
No. The 30% federal residential credit (Section 25D) ended for systems placed in service on or after January 1, 2026. If you have a state rebate, utility rebate, or another incentive, enter it as a percentage in the 'Other incentive' field — don't assume a federal credit applies unless you're specifically in a leased/PPA arrangement, which this calculator does not model.
How accurate is this estimate?
It is a simplified planning estimate, not a quote. It assumes your utility credits exported solar at close to your full retail rate (true under simple net metering, often not true under reduced net billing schemes), and it does not account for future electricity rate changes or panel output degradation over time. Use it to compare scenarios, then confirm real numbers with 2-3 independent installer quotes.
What are "peak sun hours" and how do I find mine?
Peak sun hours measure total daily solar energy, not daylight length — a rough national average for the U.S. is around 4-5 hours per day, but sunny states like Arizona often see 6+ while cloudier northern states can be closer to 3-4. Your installer can give you a site-specific figure, or you can look up your location on a public solar irradiance map such as NREL's.