Solar Panel Payback Calculator

How it works

Annual production = system size × production per kW. Annual savings = production × your electricity rate. Payback period = install cost ÷ annual savings. The 25-year figure subtracts the install cost from 25 years of savings. This is a simple-payback model: it ignores rate inflation (which shortens payback) and gradual panel degradation (which lengthens it), so treat it as a clear ballpark.

Worked example, step by step

Take the default numbers above: a 6kW system costing $15,000 after incentives, producing 1,300 kWh per kW per year, with electricity at $0.17/kWh.

Annual production = 6 kW × 1,300 kWh/kW = 7,800 kWh.

Annual savings = 7,800 kWh × $0.17 = $1,326.

Payback period = $15,000 ÷ $1,326 = 11.3 years.

Net savings over 25 years = ($1,326 × 25) − $15,000 = $18,150.

So this particular system pays for itself just past the 11-year mark, then keeps saving money for another 14 years of its expected life — roughly $18,150 net, before accounting for any electricity price rises.

What actually moves your payback period

Your electricity rate matters more than almost anything else — the calculator above shows why: double the rate and you roughly halve the payback period. Regions with expensive grid power (much of the Northeast US, California, most of Europe) see solar pay back in 6-9 years; regions with cheap power can see 12-15+ years.

Sun exposure is the second lever. A well-oriented, unshaded south-facing roof in Arizona might produce 1,600+ kWh per kW per year; a partially shaded roof in a cloudy climate might only manage 900-1,000. Get a real production estimate from an installer rather than assuming the national average.

Financing changes the picture too — a cash purchase gets you the full payback shown here, but a solar loan adds interest cost that stretches the true break-even point, while a solar lease or PPA usually means you never own the system and the "payback" concept does not apply the same way.

Finally, panel degradation (typically 0.3-0.5% output loss per year) very slightly extends real payback beyond this simple model, while rising electricity prices (which this model deliberately ignores) tend to shorten it by roughly the same amount — the two effects often approximately cancel out over 25 years.

Frequently asked questions