Solar Panel Payback Calculator
Years to break even on a solar system
A $22,000 solar system that offsets 90% of a $160 monthly power bill pays for itself in about 11.2 years and comes out $36,910 ahead over 25 years, if electricity prices rise 3% a year. The 30% federal credit ended for systems placed in service after 2025, so enter only the state or utility incentives you actually qualify for.
How solar payback works
This solar payback calculator doubles as a solar ROI calculator: the same inputs give both the break-even year and total solar panel savings.
Subtract incentives from the system cost to get your net cost, then work out how long the annual bill savings take to cover it. Offsetting 90% of a $160 monthly bill saves $1,728 in year one, so a $22,000 system with no incentives takes about 11.2 years to repay itself.
Estimate only — not financial advice. Get real quotes and check the incentives currently available where you live.
The 30% federal solar credit ended with 2025
The Residential Clean Energy Credit paid 30% of the cost of home solar placed in service from 2022 through 31 December 2025. The IRS states that it is not available for any property placed in service after that date, so a homeowner buying a system in 2026 cannot claim it. That is why incentives default to 0% here. State tax credits, utility rebates and performance payments still exist in some areas; enter their combined value as a percentage of system cost.
The difference is large. The same $22,000 system paid back in 8.1 years with the credit and takes 11.2 without it, and its 25-year net gain falls from $43,510 to $36,910. A payback figure quoted from before 2026 almost certainly assumes the credit.
Flat savings for 25 years is the wrong model
Most payback calculators divide net cost by year-one savings and stop. That treats your electricity bill as frozen for a quarter of a century, which it will not be — and it also ignores that panels slowly lose output. Both effects are modelled here, and together they matter enormously:
| Assumption | Payback | 25-year savings | Net gain |
|---|---|---|---|
| Flat rates, no degradation | 12.7 yr | $43,200 | $21,200 |
| 3% rate rises, 0.5% degradation | 11.2 yr | $58,910 | $36,910 |
| 5% rate rises, 0.5% degradation | 10.3 yr | $76,747 | $54,747 |
At a fairly ordinary 3% electricity inflation, the 25-year net gain is $36,910 rather than $21,200 — 74% higher than the flat model suggests. Payback shortens from 12.7 years to 11.2. Rising utility rates are the largest single factor in solar economics and the one most commonly left out.
The two rates to enter
- Electricity price inflation. US residential rates have historically risen around 2 to 4% a year on average, though with considerable regional variation and some sharp recent moves. 3% is a defensible middle assumption; check your own utility's history if you can.
- Panel degradation. Modern panels lose roughly 0.5% of output per year, and most carry a warranty guaranteeing about 85 to 90% of rated output at year 25. It works against you, but it is much smaller than rate inflation works for you.
At 3% inflation and 0.5% degradation, year-25 savings are $3,115 against $1,728 in year one — still nearly double, despite the panels being a quarter-century old.
What the payback figure does not include
Four things this calculation leaves out, two in each direction:
| Makes solar look better | Makes solar look worse |
|---|---|
| Added home resale value | Inverter replacement at 10 to 15 years |
| Protection from future rate spikes | Opportunity cost of the capital |
| Net metering export credits | Loan interest if financed |
| — | Roof replacement while panels are installed |
The inverter is the one people forget. String inverters typically need replacing once in a system's life at $1,500 to $3,000, which is a real cost landing right around the payback point. And if your roof has under fifteen years left, replacing it before installing is far cheaper than removing and refitting panels later.
On the other side, net metering rules decide what your exported power is worth, and they have been changing unfavourably in several states. Whether you are credited at retail rate, wholesale rate, or on a time-of-export basis can change the economics substantially — check your utility's current tariff rather than assuming.
Buying, financing or leasing
| Option | Upfront | Who owns it | Lifetime return |
|---|---|---|---|
| Cash purchase | Full cost | You | Highest |
| Solar loan | Little or none | You | Reduced by interest |
| Lease or PPA | None | The provider | Lowest |
Cash gives the shortest payback and the most lifetime savings. A loan spreads the cost and adds interest, which lengthens payback but can still be sensible. Leases and power-purchase agreements require nothing upfront and hand most of the savings to the provider — and any tax benefit belongs to the provider too, because it owns the system, not you. They also complicate a house sale, since the agreement must transfer to the buyer.
Work out your current bill first with the electricity cost calculator, and if a loan is involved, the loan calculator shows what the interest adds.
What the solar payback estimate assumes
Net cost is system cost × (1 − incentives). Year-one savings are monthly bill × 12 × offset percentage. Savings are then projected year by year for 25 years, growing with electricity price inflation and shrinking with panel degradation, and payback is the point where cumulative savings cross net cost.
- Year-by-year modelling, not a flat multiple. Each year's saving is year-one × (1 + inflation)^(n−1) × (1 − degradation)^(n−1), so payback lands between years rather than on a whole number.
- Inflation defaults matter. US residential rates have historically risen roughly 2 to 4% a year with wide regional variation. Degradation of 0.5% a year reflects typical modern panel warranties.
- Bill offset is taken at face value. Real output depends on roof orientation, shading, latitude and weather, none of which are modelled. A quote based on a site assessment is the only reliable source for that figure.
- Not included: inverter replacement (typically $1,500 to $3,000 at 10 to 15 years), loan interest, opportunity cost of capital, roof works, maintenance, and any change to net metering rules.
- Incentives default to 0%. The 30% federal Residential Clean Energy Credit is not available for systems placed in service after 31 December 2025. State tax credits, rebates and performance payments differ in timing and eligibility; enter their combined value as one percentage.
Reviewed September 2026.
Sources, checked
- Residential Clean Energy Credit, Internal Revenue Service. The 30% credit is not available for property placed in service after 31 December 2025.
- Photovoltaic Degradation Rates: An Analytical Review (Jordan and Kurtz), National Laboratory of the Rockies (formerly NREL). The median degradation of 0.5% a year across nearly 2,000 measurements.
Figures reviewed . Every worked example on this page is checked against the calculator above.
Solar Panel Payback Calculator: frequently asked questions
How long until solar pays for itself?
It depends mostly on the system price and your bill. A $22,000 system offsetting 90% of a $160 bill pays back in about 11.2 years assuming 3% electricity price inflation, or 12.7 years if rates stayed flat. With the 30% federal credit that applied through 2025, the same system paid back in 8.1 years.
Why does electricity price inflation matter so much?
Because it compounds over 25 years. At 3% annual rate rises the 25-year net gain is $36,910 rather than $21,200 under a flat model — 74% higher. It is the largest single factor and the one most often omitted.
How much do solar panels degrade?
About 0.5% of output per year for modern panels, with most warranties guaranteeing 85 to 90% of rated output at year 25. It works against you but is far smaller than electricity price inflation works for you.
Is there still a federal solar tax credit?
Not for a homeowner buying a system in 2026. The 30% Residential Clean Energy Credit covered systems placed in service through 31 December 2025, and the IRS states it is not available for property placed in service after that date. State tax credits and utility rebates still exist in some areas: enter their total as a percentage of system cost.
What costs does a solar payback calculation miss?
Inverter replacement at 10 to 15 years, usually $1,500 to $3,000, plus loan interest if financed and the opportunity cost of the capital. On the other side it omits resale value and net metering export credits.
Should I replace my roof before installing solar?
If it has under about fifteen years left, yes. Removing and refitting panels to replace a roof underneath them costs far more than sequencing the work correctly in the first place.
Is a solar lease or PPA worth it?
It requires nothing upfront and returns the least. The provider owns the system, keeps any tax benefit and most of the savings, and the agreement has to transfer to any buyer when you sell. Cash purchase returns the most.
Do solar panels add value to a home?
Owned systems typically do, since buyers value the lower bills. Leased systems are harder to transfer and can complicate a sale, which is another reason ownership gives the cleaner financial picture.