SOLAR PAYBACK CALCULATOR · RUNS IN YOUR BROWSER · NOTHING UPLOADED

Will this solar quote pay for itself?

Enter the numbers from a solar quote and your electric bill to get the payback year, the 25-year net gain, NPV and IRR, and how the answer moves if your utility pays less for exported power, prices rise slower, or the panels produce less.

Nothing you type leaves this browser tab. Illustrative estimates, not advice. Not legal, tax, or financial advice.

Your system

Your electricity

Over the years

Financing (optional)

Fill in your system and electricity price, then click Calculate payback.

How it is calculated

Production = system kW x yearly kWh per kW, reduced each year by the degradation rate. Each year's savings = production x share used yourself x import price, plus production x the rest x export credit; both prices rise by the yearly increase. Costs are maintenance, an inverter replacement in the year you choose, and loan payments while the loan runs. Upfront outlay = system cost minus incentives minus any loan. Payback is the year cumulative cash flow turns positive, interpolated within the year. NPV discounts each year's cash flow at the discount rate; IRR is the rate at which NPV is zero.

Not modelled: batteries, time-of-use and demand charges, utility fixed fees, income tax, property tax and home value effects, roof work, panel or inverter warranty claims, shading, and export credit rules that change over time. Unverified: checked by hand calculation and unit tests only. Use the production estimate and price from your own quote and bill.

Common questions

How long does it take for solar panels to pay for themselves?

Divide what you pay up front by what the system saves you each year, then account for rising electricity prices, panel degradation and any inverter replacement. This tool does that year by year and reports the year cumulative savings pass your outlay, along with the 25-year net gain, NPV and IRR.

What is the difference between net metering and net billing?

Under full net metering the utility credits each exported kWh at the same price you pay for imports. Under net billing the credit is lower, often a fraction of the retail price, so only the electricity you use yourself is worth the full rate. Set the export credit to see how much this changes your payback; confirm your utility's current rule.

How does the export credit change my solar payback?

The lower the credit, the more your savings depend on using the power yourself. The tool re-runs your system at full net metering, half and a quarter of your import price so you can see the range.

Should I include incentives in the calculation?

Enter the dollar amount of any rebate or credit you are sure to receive as a reduction of upfront cost. Incentive rules change, and this tool does not know which apply to you, so it uses only the number you enter. Ask an installer or a tax professional what applies.

Is a solar loan worth it compared to paying cash?

Enter the loan amount, rate and term. Loan payments are counted as yearly cash outflow, so payback is later than for cash, but you commit less up front. Compare the NPV and the year cumulative cash turns positive under both.

How accurate is the yearly production estimate?

It is whatever you enter. Use the production estimate from your installer's quote or a public estimator for your address and roof. The tool also shows the result if production is 15 percent below that figure.

Does it include batteries or time-of-use rates?

No. Batteries, time-of-use pricing, demand charges and utility fixed fees are not modelled. Home value effects and taxes are not included either.

Is my information uploaded anywhere?

No. Everything you type stays in this browser tab. There are no accounts, cookies or analytics vendors.