Solar Payback Estimator
Rooftop solar is either one of the best investments a homeowner can make or a very expensive roof ornament — and the difference is almost entirely your electric bill and your sunlight. Plug in your system cost, monthly bill, and sunlight zone for an honest payback estimate and 25-year savings range.
Your numbers
Your estimate
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25-year savings
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Cumulative net savings
| Year | Net savings |
|---|
How the math works
These are the assumptions behind the estimate — rounded, stated plainly, and the same for everyone. Real quotes vary; treat this as a screening tool, not a quote.
| Assumption | Value used |
|---|---|
| Bill offset | A well-sized system covers 85% of the annual bill in an average zone, 68% in a low-sun zone, 100% in a high-sun zone (capped at the full bill) |
| Panel degradation | 0.5% per year — panels produce slightly less each year |
| Electricity price escalation | 3% per year (mid estimate); the savings range shows 2% and 5% bounds |
| Analysis period | 25 years — the typical panel warranty period |
| Payback method | The year cumulative savings first exceed the net system cost (accounts for rising rates and degradation) |
Not included: financing interest, maintenance or inverter replacement (~$2,000–$3,000 around year 12–15), net-metering rules in your state, or resale value of the home. If you finance, the real payback is longer — compare the loan's total cost against the savings here. Installer quotes remain the final word; this tool's job is telling you whether a quote is even in the ballpark.