Solar Payback Period in 2026: How to Calculate It Without the Federal Tax Credit

Solar payback period is the number of years it takes for bill savings to equal what you paid for the system. In 2026 the starting cost is higher for homeowners who buy, because the 30% federal credit no longer applies to newly installed systems. That makes the other two inputs, your electric rate and your utility’s export rules, matter more than before.

The Formula

Simple payback (years) = net system cost ÷ first-year bill savings

• Net system cost = installed price − incentives you actually qualify for
• First-year bill savings = (kWh used on site × retail rate) + (kWh exported × export credit rate)

Simple payback ignores panel degradation and rate changes. The worked examples below include both.

What Changed: The Federal Credit

The IRS states that the Residential Clean Energy Credit (Section 25D) “will not be allowed for any expenditures made after December 31, 2025.” The IRS treats an expenditure as made when the original installation is completed, so paying before year-end did not qualify a system installed in 2026.

Two things remain:

• Carryforward. The IRS says excess unused credit from a qualifying system can be carried forward to reduce tax owed in later years.
• Leases and power purchase agreements. In those, a company owns the system and you pay it monthly. EnergySage reports the share of installers quoting these options rose from about 14% to about 41% in the first half of 2026. Payback does not apply the same way, because you have no upfront cost to recover. Compare the monthly payment and its yearly escalator with your expected bill savings instead.

State, utility and local incentives vary. Subtract only those you have confirmed in writing. This is general information, not tax advice.

The Inputs, and Where to Get Them

Production varies widely by location and roof. Do not reuse our 1,300 kWh per kW figure. PVWatts is free and uses your address, tilt and direction.

Worked Example

Cost: 7,000 W × $2.57 = $17,990

Year-one production: 7 kW × 1,300 kWh = 9,100 kWh

Scenario A, full retail net metering at 18.2¢:

• Savings: 9,100 × $0.182 = $1,656 a year
• Simple payback: $17,990 ÷ $1,656 = 10.9 years

Scenario B, net billing, half the output exported at 7¢:

• Used on site: 4,550 × $0.182 = $828
• Exported: 4,550 × $0.07 = $319
• Savings: $1,147 a year
• Simple payback: $17,990 ÷ $1,147 = 15.7 years

How Much Each Input Moves the Result

All rows use the same $17,990 system producing 9,100 kWh in year one. These are our illustrations, not forecasts.

For comparison, scenario A with the old 30% credit would have cost $12,593 and paid back in 7.6 years on the simple formula. Losing the credit adds a little over three years in that case.

Three things stand out:

1. The electric rate is the biggest lever. Going from 12¢ to 30¢ cuts payback from about 15 years to about 6.
2. Export rules come next. Scenario B takes four years longer than scenario A with the same system and the same rate. The 7¢ credit is close to what Georgia Power pays for exports in 2026, as covered in our Georgia rate article.
3. Using more of your own power helps under net billing. Moving from 50% to 70% self-use saves two years in our example.

What the Formula Leaves Out

• Fixed and minimum charges. Solar reduces per-kWh charges. It usually does not reduce the fixed monthly charge, and some solar tariffs add a minimum bill or a per-kW fee. See our guide to reading your electric bill.
• Use your per-kWh rate, not your all-in rate. Dividing your total bill by kWh includes the fixed charge and overstates savings.
• Financing. Loan interest and dealer fees raise the true cost. Use the total of all payments, not the cash price.
• Equipment replacement. An inverter may need replacing during the system’s life. Ask for the inverter warranty term and a replacement price.
• Time-of-use rates. Savings depend on when you produce and when you use power, not only how much.
• Rule changes. Export credit rates can be reset by regulators. Ask whether your rate is locked and for how long.
• Rate growth is not guaranteed. Georgia Power’s bills fell in June 2026. EIA projects the national average rising to 18.6¢ in 2027, but your utility may differ.

Panel warranties typically run 20 to 25 years according to NREL, so a payback beyond about 15 years leaves limited time to come out ahead.

How to Run Your Own Numbers

1. Get your last 12 bills. Add up kWh and note the per-kWh charges.
2. Look up your utility’s current solar tariff and find the export credit rate, any minimum bill and any solar-specific fee.
3. Run PVWatts for your address and the quoted system size.
4. Ask each installer for the share of production they expect you to use on site, and how they calculated it.
5. Compute first-year savings with the formula above, then divide the full contract price by it.
6. Compare that with the payback on the installer’s proposal. If theirs is much shorter, ask which rate escalation and export credit they assumed.

Limitations

The example uses one national median price from a single marketplace, one assumed production figure and a national average rate. Real quotes, roofs and tariffs vary widely. The 2% rate growth is an assumption, not a forecast. We did not model batteries, loans, taxes on savings, home value or state incentives. Nothing here is a guarantee of savings or personal financial or tax advice.

Sources

• IRS, FAQs on modification of sections 25C, 25D and others under Public Law 119-21 (FS-2025-05, Aug. 21, 2025)
• IRS, Residential Clean Energy Credit
• EIA, Short-Term Energy Outlook: Electricity, Coal, and Renewables (released Sept. 9, 2026)
• NREL, “STAT FAQs Part 2: Lifetime of PV Panels”
• NREL, PVWatts Calculator
• EnergySage, “Six months after the solar tax credit ended, the industry found a workaround,” updated Sept. 30, 2026