Assumes 3%/yr rate increases, 0.5%/yr panel degradation and no federal tax credit (the 30% §25D credit ended for systems installed after Dec 31, 2025). How we calculate
Data approachEIA rates · NREL sun hours · 2026 federal policy · methodology
Commercial solar averaged $1.77 per watt in the second quarter of 2026, according to Wood Mackenzie and the Solar Energy Industries Association (SEIA). At that price, a 25 kW rooftop system costs about $44,250 before incentives, and the federal 30% Investment Tax Credit can still cut that figure, provided the project meets a deadline that has tightened sharply this year. This guide walks through what small business solar costs, how to calculate payback with transparent assumptions, which incentives apply, and what to check before you sign.
The most important variable is your electricity rate. The U.S. Energy Information Administration (EIA) reports a 2024 national average commercial price of 12.75 cents per kilowatt-hour, with large state differences: California averaged 25.54 cents and Massachusetts 20.90 cents, while Louisiana and Arkansas were near 10 cents. The higher your rate, the faster solar pays back.
💰 System Cost
What Does a Commercial Solar System Cost in 2026?
Wood Mackenzie and SEIA put the average US commercial system price at $1.77 per watt in Q2 2026, up 5.6% from a year earlier, even though distributed-market module prices fell 16% to $0.37 per watt. Modules are now a small share of the bill; installation labor, permitting, tariffs on other components, and interconnection drive the price. That national figure comes from a bottom-up cost model for the whole commercial segment, which includes larger projects. Small rooftop systems tend to cost more per watt because design, permitting and interconnection costs are spread over fewer kilowatts, so treat $1.77 as a baseline and collect at least three written quotes.
Data visualization
Installed cost by system size at the $1.77/W national commercial average. A 25 kW system costs $44,250 before incentives and $30,975 after the 30% Section 48E credit. Source: Wood Mackenzie/SEIA Q2 2026; Green Energy Calculators calculation (kW x 1,000 x $1.77).
Chart summary: At $1.77 per watt, installed cost scales from $17,700 for a 10 kW system to $177,000 for 100 kW before incentives, and the 30% credit removes $13,275 from the 25 kW example. The credit applies only to projects that meet the Section 48E deadline discussed below, and small rooftops often price above the national segment average.
To show how the price flows through to your budget, the table below applies three price points to a 25 kW system. The first is the published national commercial average. The other two are assumed higher-cost scenarios for small or complicated rooftops, not published averages.
Price per watt
Gross cost (25 kW)
After 30% ITC
$1.77 (national commercial average)
$44,250
$30,975
$2.50 (assumed)
$62,500
$43,750
$3.00 (assumed)
$75,000
$52,500
Several site factors can push a quote up: a membrane roof that needs ballasted racking, shading from neighboring structures, a structural assessment, or an electrical panel upgrade. Get the roof and electrical service assessed before you compare bids.
Size the system from your own data rather than a rule of thumb. Pull 12 months of kilowatt-hour usage from your utility bills, then use NREL’s free PVWatts calculator to estimate annual production per kilowatt for your address and roof orientation. Dedicating more roof area than you can use is a common and costly mistake. For a broader look at pricing across system sizes, see our guide to How Much Do Solar Panels Cost in 2026.
Equipment and labor also vary by location. Installers in California and New York often quote higher than those in Texas or Florida, partly because of permitting complexity and local labor markets. Many tier-1 panel makers offer 25-year or longer performance warranties, but the guaranteed output at year 25 differs by manufacturer, so compare it line by line. Inverters usually need replacement once during a 25-year life; ask each installer for the inverter warranty length and a replacement quote so your model reflects it.
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📈 Payback Period
How to Calculate Solar ROI for Your Small Business
The basic formula is: (annual savings − annual costs) ÷ net investment × 100. The harder part is choosing honest inputs, so here are the assumptions behind the examples in this guide:
System: 25 kW rooftop array producing 35,000 kWh per year (an assumed 1,400 kWh per kW; your site will differ, so check PVWatts).
Electricity price: 12.75 cents per kWh, the 2024 EIA national commercial average. Year-one savings: 35,000 × $0.1275 = about $4,463.
Escalation and degradation: a 2.5% annual rate increase (an assumption, not a forecast) and 0.5% annual panel degradation, which matches the median rate reported by NREL research.
Excluded: operations and maintenance, inverter replacement, financing costs and tax depreciation, which you should add for your own case.
On those inputs, cumulative 25-year bill savings come to about $142,700. Simple payback (net cost divided by year-one savings) ignores escalation, so it is deliberately conservative: $30,975 ÷ $4,463 is about 6.9 years with the 30% credit, and $44,250 ÷ $4,463 is about 9.9 years without it. The chart below applies the escalation and degradation assumptions year by year. For state-level payback data with the ITC applied, see our guide to Solar Panel Payback Period by State.
Data visualization
Cumulative cash flow for a 25 kW system, Year 0 to Year 25, at $1.77/W. The line with the 30% ITC turns positive in Year 7 and the line without it in Year 10. Assumes 12.75 cents per kWh (EIA 2024 national commercial average), 35,000 kWh per year, 2.5% annual rate escalation and 0.5% annual degradation; excludes O&M, inverter replacement, financing and depreciation.
Chart summary: With 2.5% annual rate escalation and 0.5% degradation applied, cumulative cash flow turns positive after about 6.6 years with the 30% credit and about 9.1 years without it, slightly faster than the 6.9 and 9.9 years of simple payback. By Year 25 the cumulative gain reaches roughly $111,700 with the credit and $98,500 without it, before O&M, inverter replacement, financing and tax depreciation.
Electricity prices vary widely by state, and so does the speed of payback. The chart below uses EIA’s 2024 state data for commercial customers.
Data visualization
Average commercial electricity price by state, 2024 (cents per kWh). California averages 25.54 cents versus the 12.75-cent US average. Green: above 20 cents; yellow: 11.5 to 13 cents; orange: below 11.5 cents; blue: US average. Source: EIA Electric Power Annual, data for 2024.
Chart summary: California’s commercial rate of 25.54 cents per kWh is more than double the 12.75-cent national average, and Massachusetts is at 20.90 cents. Businesses in these states avoid more cost per kilowatt-hour produced, so payback is generally shorter, all else equal. In lower-rate states such as Louisiana and Arkansas (about 10 cents), expect longer payback unless installed prices or incentives offset it.
Two cautions apply to any ROI model. First, many commercial tariffs include demand charges based on your peak kilowatts, and solar alone often reduces those charges less than it reduces energy charges, so model your actual rate schedule. Second, net metering and export compensation vary by state and utility, so confirm how your utility credits exported power before sizing the system. You can run your own numbers with the commercial solar ROI calculator.
🏛️ Incentives
Federal and State Incentives, and the 2027 Deadline
Federal ITC (Section 48E). The Clean Electricity Investment Credit provides a credit of up to 30% of eligible solar system cost, claimed on IRS Form 3468. It is a dollar-for-dollar reduction of federal tax, not a deduction, and unused credits can generally be carried forward. Systems with a maximum output under 1 MW AC are exempt from the prevailing-wage and apprenticeship requirements that apply to larger projects.
The deadline is the key change. The One Big Beautiful Bill Act (Public Law 119-21, signed July 4, 2025) shortened the solar credit. Solar projects that began construction by July 4, 2026 keep the standard multi-year window to be placed in service. A project that did not begin construction by that date can claim the credit only if it is placed in service by December 31, 2027. That date has passed, so a business planning a new system today should work backward from a 2027 commissioning date, including permitting and utility interconnection time. Foreign-entity-of-concern (FEOC) sourcing rules can also apply to projects that began construction after 2025, so ask your installer how they document compliance.
Depreciation. The same law permanently restored 100% bonus depreciation for qualifying property acquired after January 19, 2025. When you claim the ITC, the depreciable basis is reduced by half of the credit, to 85% of cost. On the $44,250 example system, the basis is $37,612.50. For a C-corporation with enough tax liability at the 21% federal rate, that is roughly $7,900 of first-year tax savings, in addition to the $13,275 credit. Together they equal about 48% of gross cost, which would put net cost near $23,100 and simple payback near 5.2 years. That outcome depends on having enough tax liability to use both benefits, and pass-through owners apply their own rates, so have your CPA model it. Use the solar tax credit calculator for a first estimate.
State and utility incentives. These vary by state and change often, and many are limited to homeowners. For example, New York’s 25% solar equipment credit (capped at $5,000) and Arizona’s 25% credit (capped at $1,000) apply to residential systems, so they generally do not reduce a business-owned system’s cost. Some states offer sales tax exemptions, property tax exclusions, or utility rebates for commercial systems. Check the Database of State Incentives for Renewables & Efficiency (DSIRE) and your utility’s commercial program page before you finalize a financial model. The 30% homeowner credit (Section 25D) expired on December 31, 2025, so it is not an option for any new system.
💳 Financing
Financing With a Loan or Buying Outright
Owning your system usually delivers the highest lifetime return but requires capital or financing. Businesses can use commercial bank loans, equipment financing, or, where eligible, SBA 7(a) or 504 loans. Interest rates depend on your credit, loan term and lender, so compare written offers instead of relying on a single quoted rate.
To see the cash-flow effect, take an illustrative $44,250 loan at 7.5% over seven years. The payment is roughly $680 per month. In the earlier model, year-one bill savings are about $372 per month, so cash flow can be negative during the loan term, before counting the ITC and depreciation tax benefits. After the loan is repaid, the full bill savings flow to the business for the rest of the system’s life. A lower monthly payment from a longer term usually raises total interest, so compare total cost as well as the monthly figure. Run side-by-side scenarios in the solar loan calculator.
Because the tax benefits depend on your tax liability and on the placed-in-service deadline above, ask your CPA to model the timing of the credit and depreciation against your loan draw schedule.
🔋 Leases & Storage
Leases, PPAs and Battery Storage Add-Ons
A lease or power purchase agreement (PPA) requires little or no upfront capital. Under a lease, you pay a fixed monthly amount; under a PPA, you pay for each kilowatt-hour the system produces. In both cases the provider typically owns the equipment and claims the tax credit and depreciation, which are usually reflected in your price. Lifetime savings are generally lower than with ownership, but a lease or PPA can suit businesses with limited tax liability, tight cash flow, or a rented building where the landlord controls capital improvements. Tax-exempt organizations may be able to receive the credit as an elective payment if they own the system, so ask a tax advisor before choosing a third-party structure. Review the contract term, annual price escalator, buyout options and what happens if you sell the building. Because PPA pricing often relies on tax credits, ask how the provider’s pricing accounts for the 2027 deadline.
Battery storage is increasingly relevant for businesses with demand charges, time-of-use rates, or outage risk. Under Section 48E, energy storage can qualify for the credit on a longer timeline than solar, and standalone storage can be eligible, subject to the program’s rules, including FEOC requirements. The OBBBA’s accelerated 2027 cutoff applies to solar and wind, not to storage. A battery adds cost and does not always pay back on its own, so request quotes for both solar-only and solar-plus-storage, using your actual tariff and interconnection rules. Some utilities restrict exports or charge fees that change both systems’ economics.
Sources and Methodology
Wood Mackenzie and SEIA, US Solar Market Insight Q3 2026 (system prices, Q2 2026). SEIA Solar Market Insight
U.S. Energy Information Administration, Electric Power Annual, data for 2024 (state commercial prices). EIA Electric Power Annual
One Big Beautiful Bill Act, Public Law 119-21 (Section 48E deadlines; bonus depreciation).
NREL PVWatts for site-specific production estimates. PVWatts
Payback, savings and loan figures are Green Energy Calculators illustrations based on the stated assumptions. They are not quotes or tax advice; consult a licensed installer and a tax professional.
Related calculators
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Direct answers for US homeowners — sized for a $150/month electric bill.
The national average commercial solar system price was $1.77 per watt in Q2 2026, according to Wood Mackenzie and SEIA. At that benchmark, a 25 kW system costs about $44,250 before incentives. Small rooftop projects tend to price above the segment average, so it is worth modeling a higher range, such as $2.50 to $3.00 per watt ($62,500 to $75,000 for 25 kW), until you have written quotes. Roof type, electrical upgrades and local permitting move the final price.
Yes, but timing now decides eligibility. Under the One Big Beautiful Bill Act, the 30% Section 48E credit for solar applies to projects that began construction by July 4, 2026, or that are placed in service by December 31, 2027. That July date has passed, so a project that has not started construction must be operating by the end of 2027. Projects under 1 MW AC are exempt from prevailing-wage and apprenticeship rules. Confirm eligibility with a tax professional.
In our illustrative 25 kW model (35,000 kWh per year at 12.75 cents per kWh, the 2024 EIA national commercial average), year-one savings are about $4,463. Simple payback is about 6.9 years at $1.77 per watt with the 30% ITC, and about 9.9 years without it. At $2.50 to $3.00 per watt, payback with the ITC stretches to about 9.8 to 11.8 years. Higher local electricity rates and depreciation shorten payback; low rates lengthen it.
A business owner with enough tax liability can combine the 30% ITC with 100% bonus depreciation, which was permanently restored for qualifying property acquired after January 19, 2025. The ITC reduces the depreciable basis by half the credit, to 85% of cost. On a $44,250 system, that is a $13,275 credit plus about $7,900 of first-year federal tax savings for a C-corporation at the 21% rate. Pass-through owners use their own rates, so a CPA should model it.
Buying generally captures the most lifetime value because the owner claims the ITC and depreciation. With a lease or PPA, the provider typically keeps those tax benefits and passes some value back through the price. Leases and PPAs fit businesses with little tax liability, limited cash, or a rented building. Before signing, review the term, annual price escalator, buyout terms, and what happens if the provider loses expected tax credits.
$150/month electric bill by state
System size and payback vary by electricity rate and sun hours — see your state.
18.19¢/kWh — US average residential price. Source: EIA Electric Power Monthly, Table 5.6.B (year-to-date through July 2026), residential average retail price (July 2026) (EIA)
Solar production
4.5 peak sun hours/day × 0.82 system derate. Approximate state-average daily solar resource (peak sun hours) based on NREL solar resource data (NSRDB); not location-specific — use NREL PVWatts for an address-level estimate. (NREL PVWatts)
Installed price
$3.00 per watt before incentives. Blended 2026 US residential installed price used by this site; EnergySage marketplace reported about $2.60/W (mid-2026); full-market medians are higher.
Federal tax credit
$0 for homeowner-owned systems installed in 2026 — the 30% §25D credit ended Dec 31, 2025 (IRS)
Net metering
National blend — solar assumed to offset 75% of the bill (87% in full-retail net-metering states, 55–70% elsewhere).
Estimates only — not tax, legal or financial advice. Get at least three installer quotes and confirm incentives with your utility and a tax professional.