Solar panel ROI calculator
Pick your state, system size and electricity rate. See real payback period, 25-year savings and break-even point — with or without the federal tax credit. Numbers sourced from NREL PVWatts and EIA state averages.
Your situation
All fields prefilled with state averages. Override anything you know better.
Your solar payback
Real numbers, after incentives.
Breakdown
How the math works
A 25-year cash-flow simulation. Each year your panels produce slightly less (0.5% degradation), but the utility raises rates (your inflation %), so the dollar value of what you generate keeps growing. We sum every year's saving, subtract the net up-front cost, and report when the cumulative line crosses zero.
The formula in plain terms:
net_cost = (size × $/W × 1000) − federal_credit − state_rebate year_savings[y] = production × (1 − 0.005)^y × rate × (1 + inflation)^y payback = min y where Σ year_savings[0..y] ≥ net_cost
Frequently asked questions
Is the 30% federal tax credit still available in 2026?
The 30% Residential Clean Energy Credit was eliminated in July 2025 by the One Big Beautiful Bill Act. State-level incentives, net metering and SREC programs still exist in many states. The calculator's toggle lets you compare both scenarios for context.
How is payback period calculated?
Payback equals net system cost divided by cumulative annual savings, with rates inflating ~3.5%/yr and panels degrading ~0.5%/yr. Most US households today see 9–14 years post-credit-cut, vs 7–10 years when the 30% was active.
What kWh production per kW should I expect?
From ~1,100 kWh/kW in the cloudy Pacific Northwest to ~1,700 kWh/kW in the Southwest. The calculator preloads NREL PVWatts state averages — override if you know your roof's specific yield.
Should I include battery storage in the cost?
A 10 kWh home battery adds $8,000–$15,000 installed and rarely shortens payback in net-metered states. It does help in California NEM 3.0, Hawaii and parts of Texas. This tool focuses on grid-tied PV only — for battery economics see our dedicated guide.