Renewable Energy Investment ROI Calculator
Estimate the 25-year return on investment for solar, wind, or geothermal installations. Use it when comparing system sizes, incentive packages, or electricity rate scenarios before committing to a renewable energy project.
Last updated: September 2026
Formula below · 2 sources (climate.gov, Wikipedia) · Updated Sep 2026
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About this calculator
This calculator measures the net return of a solar system over 25 years relative to your net installation cost. Annual production = systemCapacity (kW) × peakSunHours × 365 × 0.8, where 0.8 covers inverter, wiring, temperature and soiling losses (default 4.5 peak sun hours, a mid-US value). The first year's savings are production × electricityRate, and later years grow with the annual rate increase, so total 25-year savings = annualSavings × ((1 + g)^25 − 1) / g (or × 25 when g = 0). ROI (%) = (total savings − net cost) / net cost × 100, where net cost = installationCost − incentives. Panel degradation (about 0.5% per year), maintenance and discounting are not included. Enter only incentives you will actually receive: the 30% federal residential solar credit ended for homeowner systems installed after December 31, 2025.
How to use
Suppose you install a 10 kW solar system costing $30,000 in a location with 4.5 peak sun hours, with $3,000 in state rebates (net cost $27,000), an electricity rate of $0.13/kWh and a 3% annual rate increase. Annual production = 10 × 4.5 × 365 × 0.8 = 13,140 kWh, worth 13,140 × $0.13 = $1,708 in year one. 25-year factor = (1.03^25 − 1) / 0.03 = 36.46. Total savings = $1,708 × 36.46 ≈ $62,280. ROI = ($62,280 − $27,000) / $27,000 × 100 ≈ 131%, a net gain of about 1.3 times your investment over 25 years.
Frequently asked questions
How does annual electricity rate increase affect renewable energy ROI over 25 years?
Even a small rate increase compounds significantly over 25 years. For example, a 3% annual increase means electricity costs about 2.09× more by year 25 than today. The formula captures this by summing 25 years of growing savings: ((1 + g)^25 − 1) / g, which is 36.5 years' worth of today's savings at 3% instead of 25. This is why renewable energy investments become more attractive in regions with historically volatile or rising utility rates. Locking in zero-cost generation now hedges against future rate hikes.
What tax credits and incentives should I include when calculating renewable energy ROI?
In the US, the 30% federal residential clean energy credit for solar and small wind ended for homeowner systems installed after December 31, 2025 (One Big Beautiful Bill Act). Many states stack additional credits, rebates, or property tax exemptions on top of this. Utility companies sometimes offer solar buyback or net metering credits that further reduce your effective payback period. You should include only incentives you are legally eligible for and will actually receive, since overestimating them inflates your ROI figure. Consult a tax professional to confirm eligibility before relying on incentive estimates.
What is a good ROI percentage for a residential solar or wind installation?
A 25-year ROI above 100% is generally considered solid for residential renewable systems, meaning you recover more than your net cost in energy savings. Many well-sized solar installations in sunny climates achieve 200–400% ROI over their lifetime. However, ROI alone doesn't tell the whole story — payback period (typically 6–12 years for solar) and internal rate of return (IRR) give a more complete financial picture. Systems in areas with high electricity rates, strong sunlight or wind resources, and generous incentives consistently outperform those in less favorable conditions.