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Calculator

Solar Payback Calculator

Estimate system size, net cost after the federal credit, and how long solar takes to pay for itself.

Model reviewed August 2026

Payback period

9.1 years

System size
10.9 kW
Gross cost
$31,513
Net cost after credit
$22,059
Estimated 25-year savingsAssumes modest utility rate escalation
$47,769
Annual production
16,500 kWh

Estimates only. Local pricing, site conditions and code requirements change the real number.

The formula

System kW = annual kWh / (sun hours x 365 x 0.8); Payback = net cost / annual savings

Peak sun hours run about 4.0 per day in the Northeast and Pacific Northwest and 5.5 to 6.0 in the Southwest. A 0.8 derate accounts for inverter losses, temperature and soiling.

Worked example

A $220 monthly bill at $0.16/kWh implies 16,500 kWh a year — roughly a 10.9 kW system, about $19,000 net after the federal credit, paying back in about 7 years.

Frequently asked questions

How long does solar take to pay for itself?

Typical payback is 7 to 12 years, depending on your utility rate, local sun hours, roof orientation, available incentives and whether you finance the system.

Do I need a new roof before solar?

If the roof has under 10 years of life left, replace it first. Removing and reinstalling panels later usually costs $3,000-$7,000.

Sources

Sources & verification

Model vintage August 2026. The links above are the issuing agencies' own pages — we publish them so you can confirm the current rule yourself, not as evidence that each fact on this page was re-checked with them today. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing, not quotes. Permit rules change; confirm with the building department before starting work.