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Free tool · 2026 post-tax-credit edition

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, and with your state's net-metering rules already priced in. Rates, production and export value factors come from our own 50-state Solar Payback Index dataset (EIA + NREL PVWatts).

Your situation

All fields prefilled with state averages. Override anything you know better.

Typical US home: 5–10 kW. Average 2026 install: 8.6 kW.
Pre-incentive. EnergySage 2026 national median: $2.58/W — the same baseline as our Solar Payback Index. National-brand quotes run $3.10–$3.60/W.
EIA 2026 residential average for the selected state.
NREL PVWatts state average, as published in our index dataset.
Set automatically from the state's net-metering regime.
Ended by OBBBA (signed July 2025) for systems placed in service after Dec 31, 2025. Check this only if you're modelling a pre-2026 install or a hypothetical "what-if".
Some states (NY, MA, NJ) still offer 5–15% rebates. Set 0 if you don't qualify.
US average 2010–2024: 3.4%. Aggressive: 5%. Conservative: 2%.

Your solar payback

Real numbers, after incentives.

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Years to break even (rates escalating)
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25-year savings
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Total ROI

Breakdown

Gross system cost —
Federal tax credit —
State/utility rebate —
Net cost —
Year-1 production —
Export credit factor —
Year-1 savings —
Simple payback (index basis, no rate escalation) —
Assumptions: 25-year panel life, 0.5%/yr degradation, no inverter replacement priced in. Every kWh you generate is valued at your retail rate × the export credit factor above (full retail net metering 1.00, net billing 0.58, no statewide mandate 0.46) — the same value factor our Solar Payback Index applies, which is why a high-rate state without full-retail net metering still pays back slowly. The headline figure escalates your rate each year; the simple payback line above does not, and at the index defaults ($2.58/W, no credit, no rebate) it returns the same number the index publishes for that state. Beyond that, real-world payback still varies with shading, roof orientation and your specific utility tariff.

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. Not every kWh is worth the full retail rate, though: what your utility pays for exported power depends on your state's net-metering regime, so each year's saving is multiplied by an export value factor — 1.00 under full-retail net metering, 0.58 under net billing / avoided-cost tariffs, 0.46 where there is no statewide mandate. 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
value_factor    = 1.00 full retail | 0.58 net billing | 0.46 no mandate
year_savings[y] = size × production × (1 − 0.005)^y × rate × (1 + inflation)^y × value_factor
payback         = min y where Σ year_savings[0..y] ≥ net_cost
simple_payback  = net_cost ÷ year_savings[0]     # no escalation — the index convention

Those are two different questions, so we report both. The headline number answers "when do I get my money back if electricity keeps getting more expensive?" The simple payback line in the breakdown freezes today's rate and answers "how many years of today's bill does this system cost?" — the deliberately conservative convention used by our Post-Credit Solar Payback Index. Leave the defaults alone ($2.58/W, credit off, no rebate) and that line returns exactly the payback the index publishes for the state you picked; the 8 kW worked examples in the best-states ranking reproduce here too, because system size cancels out when cost and output both scale with kW.

Sources & assumptions: the state dropdown loads three fields straight from our Solar Payback Index dataset (CSV, 50 states): the 2026 EIA residential rate, the NREL PVWatts annual yield per kW, and the net-metering value factor. Same numbers, same file, so a state's payback here matches the index study and the state ranking that cites it. Incentive logic from DSIRE. Since January 2026 the federal-credit field defaults to $0 (Section 25D ended for systems placed in service after Dec 31, 2025). Full breakdown on the methodology page. Built and maintained by Bruno de Madrazo.

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?

Two ways, and the calculator reports both. The headline figure runs a 25-year cash flow: net cost = gross cost minus any incentives, and each year's saving = annual production × your retail rate × your state's net-metering value factor, with panels degrading ~0.5%/yr and rates rising by the inflation % you set (3.5% by default). The simple payback line in the breakdown drops the escalation — net cost ÷ year-1 savings — the convention behind our Solar Payback Index. On the index baseline ($2.58/W, no federal credit, no rebate) the 50-state median simple payback is 11.5 years, from 5.6 in Hawaii to 29.0 in Idaho; the median was 8.1 years while the 30% credit was still available.

Does the calculator account for net metering?

Yes — it is the single biggest reason two states with similar sunshine pay back a decade apart. Picking a state loads its 2026 regime from the index dataset and applies an export value factor to every kWh generated: 1.00 in the 34 full-retail net-metering states, 0.58 in the 9 net-billing / avoided-cost states (California NEM 3.0, Hawaii, Arizona, Nevada, Michigan, Indiana, Louisiana, Arkansas, Utah) and 0.46 in the 7 states with no statewide mandate (Texas, Alabama, Mississippi, Alaska, Tennessee, South Dakota, Idaho). If your own utility publishes a different export rate, divide it by your retail rate and enter that factor.

What kWh production per kW should I expect?

In our 50-state dataset, from 926 kWh/kW in Alaska to 1,910 kWh/kW in Arizona — NREL PVWatts state averages at default tilt and orientation. The calculator preloads the value for the state you pick and degrades it 0.5%/yr across the run; override it if you know your roof's specific yield.

Should I include battery storage in the cost?

A 10 kWh home battery — an Enphase IQ Battery 10C, say — adds $11,500–$14,000 installed, and a larger 13.5 kWh Tesla Powerwall 3 runs $10,500–$14,000. Either rarely shortens payback where full-retail net metering already banks your exports at retail value. It earns its keep where exports are discounted — California NEM 3.0, Hawaii, Arizona, Nevada — or where there is no statewide mandate at all, such as Texas. This tool focuses on grid-tied PV only — for battery economics see our dedicated guide.