The Solar Panel ROI Calculator performs a full financial return analysis on any solar panel system. Enter your system cost, incentives (including the US 30% ITC), annual kWh production, electricity buy rate, export tariff, and self-consumption percentage, and the calculator runs a year-by-year cash flow model accountin..
Fully installed cost before incentives. US avg: $2.50–$4.00/W.
US: 30% federal ITC through 2032. UK: 0% VAT on solar. State/local rebates may also apply.
From installer quote or NREL PVWatts. Typically 1,200–1,500 kWh per kW installed per year.
% of solar output used directly. Remainder exported at FIT rate.
ROI RESULTS — 25-YEAR ANALYSIS
PAYBACK PERIOD
11
years
IRR
9.73%
internal rate of return
NPV (4% discount)
$13,878
25-YR TOTAL RETURN
$35,274
NET COST (AFTER INCENTIVES)
$17,500
$25,000 − $7,500 incentives = $17,500
25-YEAR CUMULATIVE CASH FLOW
ANNUAL BENEFIT (RISING WITH ELECTRICITY INFLATION)
FULL SUMMARY
✓ Positive ROI — this investment makes financial sense
At a 4% discount rate, this system generates $13,878 more than the cost of capital over 25 years. IRR of 9.73% beats a 4% savings account.
IRR BENCHMARK REFERENCE
Enter your total installed system cost — the full price before any incentives or rebates. Then enter your incentives: in the US, the federal solar Investment Tax Credit (ITC) is currently 30% of system cost through 2032. Click the '30% US ITC' button to calculate it automatically. State and local incentives vary — check the DSIRE database for your state.
Enter your annual energy production in kWh/year. This should come from your installer's quote, which is typically based on a NREL PVWatts or similar simulation. As a rough guide, a 1 kW system produces approximately 1,200–1,500 kWh/year in the US, 850–1,100 kWh/year in the UK, and 1,400–1,800 kWh/year in Australia.
Set your electricity buy rate (what you pay per kWh) and your export or feed-in tariff (what you receive for excess electricity sent to the grid). If your utility offers net metering at full retail rate, set both rates the same. If you have no export tariff or net metering, set FIT to zero. Set your self-consumption percentage — the share of solar output used directly in the home versus exported.
Use the advanced settings to adjust electricity inflation rate (historical average 2–4%/year), panel degradation (most modern panels degrade 0.3–0.5%/year), discount rate (your opportunity cost of capital — savings rate or investment return), and system life (25–30 years is standard warranty period).
Read the ROI results: payback period in years, IRR (internal rate of return), NPV (net present value), and total 25-year return. The cumulative cash flow chart shows year-by-year returns with the breakeven year marked in amber. A green verdict box confirms whether the investment beats your discount rate. Compare the IRR to the benchmark table to understand where solar fits relative to other investments.
Solar ROI calculation for a US home: Inputs: • System cost: $25,000 (8.3 kW at $3.00/W) • 30% US ITC incentive: $7,500 • Net cost: $17,500 • Annual production: 12,000 kWh/year (Year 1) • Self-consumption: 70% (8,400 kWh used directly) • Buy rate: $0.15/kWh | Export FIT: $0.08/kWh • Electricity inflation: 3%/year • Panel degradation: 0.5%/year • Discount rate: 4% Year 1 benefit: • Self-consumed: 8,400 kWh × $0.15 = $1,260 • Exported: 3,600 kWh × $0.08 = $288 • Total Year 1: $1,548/year Year 25 benefit (inflation + degradation applied): • Production: 12,000 × 0.995^24 = 10,561 kWh • Rate: $0.15 × 1.03^24 = $0.304/kWh • Benefit ≈ $2,790/year Payback: Year 11 NPV (4% discount): $13,878 IRR: 9.73% 25-year cumulative cash flow: $35,274 Net profit after investment: $35,274 − $17,500 = $17,774 real return
Last updated: April 29, 2026 · Formula verified by EagleCalculator team · Eagle-eyed accuracy for every calculation.