Solar Payback Period: How to Calculate It Honestly in 2026

Solar payback is the number of years it takes for bill savings to add up to what you paid. The quick version is simple: divide the system’s net price by first-year savings. An honest version also accounts for rising electricity rates, panels that slowly produce less, an inverter replacement, and what your money could have earned elsewhere. In 2026, with no federal credit for owned systems, realistic paybacks run about 7 to 10 years in strong cases and 10 to 15 years in typical ones. Sales quotes often show much shorter numbers, and this guide explains why.

Step 1: Simple payback

Simple payback = net system price ÷ first-year bill savings

• Net price is the full installed price minus incentives you will actually receive. For an owned system installed in 2026, there is no federal tax credit. Subtract only state or utility incentives you qualify for. See the federal solar tax credit in 2026.
• First-year savings is the money solar keeps out of your utility bill in year one. It is not production times your rate if your utility pays less for exports.

How to estimate first-year savings:

1. Estimate yearly production (kWh) for the system. Check the installer’s number against PVWatts with our production checker.
2. Estimate how much you will use at home as it is produced, and how much you will export.
3. Multiply self-used kWh by your full rate, and exported kWh by your export credit.
4. Remember that fixed monthly charges and minimum bills do not go away.

Under full retail net metering, steps 2 and 3 collapse to production × your rate. Under net billing, exports might earn a fraction of retail. In California, the Net Billing Tariff averages roughly 4 to 5 cents per exported kWh. See net metering explained.

Step 2: Adjust for what changes over time

Simple payback assumes every year looks like year one. Three things change.

Electricity rates usually rise

U.S. residential prices rose about 3.1% a year from 2005 to 2025, and about 0.5% a year after inflation, based on EIA data. Recent years have been steeper: the 2026 year-to-date average was about 6.9% above the same period in 2025. Rising rates make each year’s savings bigger, which shortens payback.

A reasonable base case is 2% to 3% a year. Check your own utility’s history with our rate history tool.

Panels produce a little less each year

Studies put median panel degradation around 0.5% a year, with a national fleet median closer to 0.75%. Hot climates degrade faster. After 25 years at 0.5%, a system produces about 89% of its first-year output.

Inverters wear out

A string inverter typically lasts 10 to 15 years and costs about $1,500 to $3,000 to replace. That is a real cost in the middle of the payback period. Microinverters usually carry 25-year warranties, though labor coverage varies. See microinverters vs string inverters.

Step 3: Discounted payback

Money spent today on solar is money that cannot earn interest or pay down a loan. Discounted payback counts each future year’s savings at a lower value to reflect that.

The discount rate should be roughly what your money would otherwise earn or cost. As of October 2026, a HELOC averaged about 7.34% (Bankrate). If you are paying cash from savings, something like 4% to 6% is reasonable.

Discounted payback is always longer than simple payback. If it is longer than you expect to own the home, solar is a weak financial bet even if simple payback looks fine.

Worked example

An 8 kW system at $3.00 per watt costs $24,000, paid in cash. It saves $2,000 in year one. We assume 3% yearly rate increases, 0.5% yearly degradation, a $2,500 inverter replacement in year 12, and a 6% discount rate.

Year	Savings that year	Running total vs. $24,000 cost	Discounted running total (6%)
1	$2,000	−$22,000	−$22,113
5	$2,206	−$13,490	−$15,171
10	$2,494	−$1,609	−$7,712
12	$120 (after $2,500 inverter)	+$1,068	−$6,306
15	$2,820	+$9,325	−$2,653
20	$3,188	+$24,512	+$2,670
25	$3,605	+$41,683	+$7,168

Results for this example:

• Simple payback: $24,000 ÷ $2,000 = 12.0 years.
• Payback with rising rates, degradation and inverter: about 10.6 years.
• Discounted payback at 6%: about 17.4 years. At 4%, about 14.7 years.
• If rates never rise: about 13.7 years, and the 25-year present value is slightly negative.

This system is a reasonable deal for a household that will stay 15 years or more. It is a poor one for a household likely to move in 7.

Why salesperson paybacks are shorter

Here is the same system as it often appears in a sales proposal:

Assumption	Honest model	Typical sales model
Rate increases	3% a year	5% a year or more
Panel degradation	0.5% a year	None
Inverter replacement	$2,500 in year 12	None
Federal tax credit	$0 (2026 owned system)	30% subtracted ($7,200)
Payback shown	About 10.6 years	About 7.2 years
25-year savings shown	About $41,700	About $78,700

None of these tweaks looks dramatic on its own, but together they cut payback by a third and nearly double the headline savings. Watch for these specific problems:

• Inflated rate increases. Some proposals and competitor calculators assume 5% to 8% a year. That has not matched the long-run national average. See inflated rate increases.
• No degradation. Production is shown flat for 25 years.
• No inverter or repair costs.
• A tax credit that does not exist. Any 2026 owned-system quote subtracting 30% is wrong. See claims of a 30% tax credit.
• Undiscounted 25-year savings. A dollar in 2050 is not worth a dollar today. See undiscounted savings.
• Inflated production estimates. Optimistic sun, ignored shade. See inflated production estimates.
• Assuming all output is worth the full retail rate in a state with net billing.
• Ignoring dealer fees. If the price is inflated by a loan fee, payback stretches further.

Paste any claim into our sales claim checker to see how it holds up.

Realistic ranges in 2026

These are our modeled ranges for owned systems with no federal credit, using the assumptions above. They are not promises.

Situation	Typical payback	Common traits
Strong	About 7 to 10 years	Rates of 25 cents or more, retail net metering, good sun, $3.00/W or less
Typical	About 10 to 15 years	Rates near the 18-cent national average, partial export credit, fair price
Weak	20 years to never	Low rates, avoided-cost exports, shade, dealer-fee loan pricing

As a rule of thumb, a payback much past 15 years is hard to justify. The system should last 25 years or more, but the longer the payback, the more room there is for something to go wrong: a move, a roof replacement, an installer bankruptcy, or a utility changing its export rules.

Payback with a loan, lease or PPA

• Loans: payback math should use the full financed cost, including interest and any dealer fee. A “1.99% APR” loan with a 25% dealer fee can add years. See solar loan dealer fees.
• Leases and PPAs: there is no payback in the usual sense, because you pay little or nothing upfront. Instead, compare total payments over the contract (including escalators) to what you would have paid the utility. See lease vs buy vs PPA vs loan.

Run your own numbers

Bottom line: Use your real price, realistic production, your actual export credit, about 3% rate growth, 0.5% degradation and an inverter replacement. If the payback still fits comfortably within the years you plan to stay, solar is likely worth it.

Our payback calculator does this for you, and the main calculator adds your state’s export rules and current costs. For the bigger picture, see is solar worth it in 2026.