Solar ROI Calculator 2026

Calculating Your Solar Return on Investment (ROI): A Complete Guide

Return on Investment (ROI) measures the profitability of your solar system as an annualized percentage, similar to how you'd evaluate a stock, bond, or CD. A solar ROI of 6-11% is common in 2026 — significantly better than most safe investments, and with the added benefit of hedging against rising electricity rates that is not available with stocks or bonds.

Unlike a stock (which can lose value), solar ROI is backed by your local utility rates and sun exposure — both highly predictable over 25 years. And unlike a CD (which is liquid), solar adds value to your home that transfers to the buyer if you sell.

How Solar ROI Compares to Other Investments

Solar's IRR (Internal Rate of Return) is directly comparable to these other investments. Unlike stocks, solar returns are not correlated with market volatility — they depend on local electric rates and sun exposure, which are more predictable over 25 years. And unlike CDs or bonds, solar returns are tax-free (the "income" is avoided electric bills, which are not taxable).

Calculating NPV (Net Present Value)

NPV converts all future solar savings into today's dollars, subtracting your initial investment. A positive NPV means solar is profitable compared to investing the same money elsewhere. Here's a simplified example:

• Investment (Year 0): $18,500 (net after ITC) in Year 0 — cash purchase
• Year 1-5 savings: $1,400-$1,700 annually (escalating with electric rate increases)
• Year 6-10 savings: $1,700-$2,100 annually (payback occurs in year 7-9)
• Year 11-15 savings: $2,100-$2,600 annually (inverter replacement ~$2,000 in year 12-15)
• Year 16-25 savings: $2,600-$4,200 annually (all pure profit)
• Discount rate: 5% (your alternative investment return — e.g., CD or bond rate)
• NPV: Approximately $15,000-$28,000 (positive — solar beats the alternative)

If NPV is positive, solar is a better use of your capital than the alternative investment you used as the discount rate. If NPV is negative, you'd be better off investing in that alternative and continuing to pay electric bills from the grid.

Factors That Boost Solar ROI

• High local electric rates: Every $0.01/kWh increase in your rate improves IRR by ~0.3-0.5%. Homeowners in MA (24¢/kWh) see 2-3% higher IRR than homeowners in WA (10¢/kWh).
• Rising electric rates: If your utility raises rates faster than our 3.5% assumption, your actual ROI will exceed the calculator estimate. In some markets (CA, Northeast), 4-5% annual increases are more realistic, boosting IRR by 1-2 percentage points.
• State/local incentives: SMART program in MA, NY-Sun, and other state incentives can improve IRR by 1-3 percentage points by reducing net system cost.
• Avoiding a roof replacement: If your roof needs replacement in year 8, the remove-and-reinstall cost reduces NPV by $2,000-$3,000. Timing solar with roof replacement avoids this cost. Ask your roofer about "solar-ready" roof installation.
• Home resale: If you sell your home 10-15 years after installing solar, the remaining system value transfers to the buyer. In most markets, you recover 70-100% of the unamortized system cost in the home sale price, which is equivalent to a 1-2% IRR "bonus."
• Electric vehicle adoption: If you buy an EV during your system's lifespan, your electricity consumption increases 30-50%, making solar ROI even stronger because you're offsetting more expensive gasoline with solar.

ROI for Different Financing Options

Your financing method changes the IRR calculation:

• Cash purchase: Highest IRR (6-11%), because you capture the full ITC and have no interest payments. The "investment" is the net system cost; the "return" is 25 years of avoided electric bills.
• Solar loan (5-7% interest): IRR drops to 3-7%, but monthly loan payments are typically less than pre-solar electric bills, creating positive cash flow from day one. The "investment" includes interest payments; the "return" is bill savings minus loan payment.
• Lease/PPA: No IRR (you don't own the system), but you save 10-20% on electric bills with $0 upfront cost. This is best for homeowners who don't qualify for the tax credit or don't want any maintenance responsibility.

Tax Implications of Solar ROI

The 30% federal ITC is a direct reduction of your tax liability — it is not a deduction (which reduces taxable income) but a credit (which reduces taxes dollar-for-dollar). To capture the full credit, you need sufficient tax liability in the year of installation. Key points:

• If your tax liability is less than the credit, the unused portion can be carried forward to future years (but not backward to prior years).
• The ITC applies to equipment AND installation costs — total project cost, not just panels. Permit fees, inverter, racking, and labor all count.
• Battery storage claims the same 30% credit when installed with solar (or retrofitted within the same tax year).
• Some states offer additional tax credits (NY, CO, OR) that stack with the federal ITC, improving ROI by 0.5-1.5 percentage points.

Comparing Solar ROI by State