Energy Calculators

Solar payback calculator (2026)

Estimate how many years rooftop solar takes to pay back in your state, now that the federal credit has ended for new systems.

In Iowa, a 7 kW system at $3.60/W ($25,200, no federal credit for 2026 installs) produces about 9,590 kWh a year (PVWatts, Des Moines) and saves about $1,636 a year at 17.06¢/kWh (August 2026, EIA), a simple payback of 15.4 years.

Production for Des Moines (PVWatts), price from EIA.

kW
$/W

Use the $/W from your quote.

Applies the 30% federal credit. Systems completed in 2026 or later get 0%.

kWh/kW

South-facing, 20° tilt, 14% losses. Shade and orientation change this.

%
¢/kWh
¢/kWh

Iowa: Retail-rate credit (net metering) (DSIRE map, May 2026). Default assumes exports are credited at the retail rate.

Simple payback
15.4 years
Annual savings
$1,636
Net cost
$25,200no federal credit
Annual production
9,590 kWh
How the export rate changes payback
Exports valued atSavings/yrPayback
0¢/kWh$818.0330.8 years
Your input: 17.06¢/kWh$1,63615.4 years
Retail: 17.06¢/kWh$1,63615.4 years

Formula: production = system kW × kWh per kW; savings = production × (share used at home × retail rate + share exported × export rate); net cost = kW × 1,000 × $/W − federal credit; payback = net cost ÷ annual savings. Ignores price changes, panel degradation, maintenance and financing.

Inputs used: system: 7 kW at $3.6/W; federal credit: 0%; production: 1,370 kWh/kW; used at home: 50%; retail: 17.06¢/kWh; export: 17.06¢/kWh.

These are estimates, not financial advice.

Source: U.S. Energy Information Administration (Aug 2026). About our data

Production: PVWatts® v8, National Laboratory of the Rockies (U.S. Department of Energy) (PVWatts 8.5.0). Export rules: DSIRE / NC Clean Energy Technology Center, “Distributed Generation Customer Credit Rates for Excess Generation” (May 2026) (May 2026). Installed price: Berkeley Lab, U.S. Distributed Solar and Storage: 2026 Data Update (Aug 2026).

Worked examples in three states

7 kW at $3.60/W, completed in 2026 (no federal credit), 50% of output used at home, exports at each state’s default rate.

StatekWh/kWRetailExport ruleSavings/yrPayback
Hawaii1,62247.18¢/kWhAvoided-cost (wholesale) credit$2,6789.4 yr
Alabama1,37616.33¢/kWhAvoided-cost (wholesale) credit$786.4532.0 yr
Nevada1,75312.72¢/kWhVaries by utility (retail for some, lower for others)$780.4432.3 yr

States with no published state-level export rate are shown with exports valued at 0 (a conservative floor).

How we calculate

production = kW × kWh per kW; savings = production × (share used at home × retail price + share exported × export rate); payback = (kW × 1,000 × $/W − federal credit) ÷ annual savings.

Production per kW: PVWatts v8 for the largest city in each state (south-facing, 20° tilt, roof mount, 14% system losses). Retail price: EIA average residential price, August 2026. Export credit: retail price in states where the DSIRE map shows retail-rate credit; 0 where there is no compensation; otherwise you enter your utility’s rate (default 0). Installed price default: Berkeley Lab median for 2025 host-owned residential systems. See the methodology.

Frequently asked questions

Is there still a federal tax credit for home solar in 2026?

No. The Section 25D residential clean energy credit does not apply to systems completed after December 31, 2025. If your system was completed in 2025 or earlier, tick the box in the calculator to apply the 30% credit. State and utility incentives may still be available.

Why does the export rate matter so much?

Every kWh you send to the grid is credited at your utility’s export rate. Under retail net metering that equals the retail price; under net billing or avoided-cost rules it can be a fraction of it. The comparison table shows payback with exports valued at 0 and at the full retail rate.

How accurate is the production estimate?

It uses NLR’s PVWatts model for a 1 kW south-facing roof array at a 20° tilt in each state’s largest city, with typical-year weather. Shading, orientation, roof pitch and local weather can change production substantially.

What does simple payback leave out?

It ignores electricity price changes, panel degradation, inverter replacement, maintenance, financing costs and the time value of money. Treat it as a first screen, not an investment analysis.

Data last updated: