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Step 4 of 9. Follow the sequence to turn a rough idea into a homeowner-ready solar plan.
Find the solar break-even year from installation cost and projected savings. Review ROI, discounting and the assumptions that change your payback estimate.
Quick answer
Simple payback = net upfront cost / annual savings when annual savings are constant; changing savings require cumulative cash flows.
Notes updated 2026-10-07
Author profile: Marcus Vance . Read the methodology and recheck local tariff, quote, and incentive details before deciding. Attribution is not a record of independent technical review.
Wattcrunch Solar Planning Report
Generated 10/25/2026 · Verify assumptions with your utility and installer.
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The model compares cumulative projected savings with net installed cost. A project may never break even within the selected horizon. Rate growth, export prices and future repairs affect the result.
Use payback for timing, ROI for net benefit relative to cost, and NPV to account for the timing of future cash flows. Compare conservative and optimistic assumptions rather than relying on one projection.
Only when annual savings stay constant. With degrading production or changing rates, accumulate each year of savings and find when the running total reaches the net upfront cost. If it never does within the modeled horizon, report no payback rather than an invented break-even year.
| Export credit | Year-one energy value | Modeled payback |
|---|---|---|
| $0.06/kWh | $1,736.00 | 14.3 years |
| $0.15/kWh | $2,240.00 | 11.0 years |
| $0.25/kWh | $2,800.00 | 8.7 years |
Illustrative assumptions: Same illustrative 8 kW, $24,000 cash system as the savings example: 11,200 first-year kWh, 50% self-use, $0.25/kWh retail, zero escalation and 0.5% annual production degradation. Repairs, financing and other ownership costs would extend these energy-only payback estimates.
Example and calculation notes updated . Method references are listed below; example rates are not verified utility tariffs.
Simple payback = net upfront cost / annual savings when annual savings are constant; changing savings require cumulative cash flows.
A $20,000 net cost with $1,500 constant annual savings returns 13.33-year simple payback. At $1,000 annual savings it takes 20.00 years; NPV also depends on discounting.
Reproducible example generated from the same calculator functions used by the tool. Inputs are illustrative, not measured customer results.
Payback alone ignores benefits after break-even and the timing of repair costs. Compare NPV too.
Use your bill or written equipment quote, run a conservative scenario, and compare the result with the same inputs in another model.
Calculation notes updated 2026-10-07. Reference links explain the method; they do not establish a current utility tariff or installer price.
Read the full methodology or save and compare your solar plan.
Treat the result as a planning range, not a promise. Re-run it with a lower and higher production estimate, your actual utility tariff, and the written installer quote.
Use the method references below to check the formula and its limitations. Input defaults and illustrative scenarios are not current tariffs, guaranteed output or live installer quotes.
Utility export rates, eligibility rules, and installer pricing can change. Confirm the applicable tariff, interconnection requirements, and tax treatment before making a purchase decision.
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Start with your actual usage, equipment or quote inputs, keep the displayed units, and change one assumption at a time. Payback alone ignores benefits after break-even and the timing of repair costs. Compare NPV too.
Simple payback = net upfront cost / annual savings when annual savings are constant; changing savings require cumulative cash flows.
A $20,000 net cost with $1,500 constant annual savings returns 13.33-year simple payback. At $1,000 annual savings it takes 20.00 years; NPV also depends on discounting.
Payback alone ignores benefits after break-even and the timing of repair costs. Compare NPV too.
Physical kW and kWh calculations use the same units internationally. Dollar results, regional defaults, emissions factors, incentives and utility guidance are US-oriented. Replace rate and production assumptions with local values; do not apply US tax or export rules abroad.
Use Print / PDF to save this page from your browser without an email address. The solar plan stores supported scenario inputs in your browser; private files should be checked and redacted before uploading for extraction.
Compare cash, loan, lease, and battery scenarios using the same production, rate, and quote assumptions before choosing a financing path.
Or browse all calculators, find rebates in the Incentive Finder, or read our solar guides.