Solar panel depreciation for a business system starts with three numbers: the installed cost, the federal investment tax credit you claim, and the depreciation method you choose. For most commercial installations placed in service in 2026, you reduce your cost basis by half the credit amount, then deduct the entire remaining basis in year one under 100% bonus depreciation. If you elect out, you spread the deductions across six tax years under the Modified Accelerated Cost Recovery System.
What Qualifies as Depreciable Solar Property
The property has to be used in a trade or business or held to produce income. Panels on the roof of the house you live in do not qualify for depreciation, though they may be eligible for the residential clean energy credit. The system must also be “placed in service,” meaning installed, connected, and ready to generate electricity on an identifiable date. That date starts your depreciation clock and controls which rules apply.
Depreciable solar property includes the photovoltaic panels, inverters, racking and mounting hardware, wiring, conduit, and other components integral to operation. Battery storage charged exclusively by the solar array also counts. Costs that serve a separate purpose do not. A roof replacement done alongside the installation is not depreciable as solar property unless the roofing material itself generates electricity, such as solar shingles. The IRS position is that only components necessary for the solar system and serving no independent purpose qualify.
Reduce Your Basis by Half the Investment Tax Credit
If you claim the federal investment tax credit, you have to reduce your depreciable basis before you calculate any depreciation. The general Section 50(c) rule reduces basis by the full credit amount, but a special rule for energy and clean electricity investment credits cuts that adjustment in half: only 50% of the credit is subtracted.1Office of the Law Revision Counsel. 26 U.S. Code 50 – Other Special Rules
The clean electricity investment credit under Section 48E has a base rate of 6% of the qualified investment. Projects meeting prevailing wage and registered apprenticeship requirements can reach 30%, with additional bonuses of up to 10 percentage points each for domestic content and energy community siting.2Internal Revenue Service. Clean Electricity Investment Credit
For a $100,000 installation claiming a 30% credit, the math runs like this:
- Investment tax credit: $100,000 × 30% = $30,000
- Basis reduction: $30,000 × 50% = $15,000
- Adjusted depreciable basis: $100,000 − $15,000 = $85,000
You depreciate the $85,000, not the original $100,000. Skipping this step inflates your deductions and creates an audit exposure.
Writing Off the System in Year One With Bonus Depreciation
The One Big Beautiful Bill Act, signed July 4, 2025, permanently restored 100% bonus depreciation for qualified property acquired after January 19, 2025.3Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One Big Beautiful Bill The phase-down that had dropped the bonus percentage to 60% in 2024 and 40% in 2025 no longer applies.
Using the $85,000 adjusted basis above, the entire $85,000 is deductible in the tax year the system begins operating. Nothing is left to depreciate in later years. Combined with the $30,000 credit, a $100,000 system generates $115,000 in first-year tax benefits, though the deduction’s cash value depends on your marginal rate. Unlike Section 179, bonus depreciation can create or increase a net operating loss, which you can then carry forward.
Bonus depreciation is automatic. You do not elect in. If you would rather spread the deductions, you can elect out of bonus depreciation for the entire asset class on your tax return. That choice makes sense when your current-year taxable income is low and you expect it to rise, making future deductions more valuable.
The Standard MACRS Schedule if You Elect Out
Solar systems that began construction before January 1, 2025, are 5-year property under Section 168(e)(3)(B).4Internal Revenue Service. Cost Recovery for Qualified Clean Energy Facilities, Property and Technology For systems that began construction after that date, Section 70509 of the One Big Beautiful Bill Act removed solar from the statutory 5-year class.5Internal Revenue Service. Publication 946 – How To Depreciate Property Certain qualified clean energy facilities placed in service after 2024 may still receive 5-year treatment through separate Inflation Reduction Act provisions; property without a specific class and no established class life otherwise defaults to 7-year. The classification matters chiefly when you elect out of bonus depreciation, because full bonus wipes out the basis in year one regardless of recovery period. For your specific project, this is worth confirming with a tax adviser.
Standard 5-year MACRS uses the 200% declining balance method with the half-year convention, spreading the cost across six tax years at these rates:6Office of the Law Revision Counsel. 26 U.S. Code 168 – Accelerated Cost Recovery System
- Year 1: 20.00%
- Year 2: 32.00%
- Year 3: 19.20%
- Year 4: 11.52%
- Year 5: 11.52%
- Year 6: 5.76%
Against the $85,000 adjusted basis, that produces annual deductions of $17,000, $27,200, $16,320, $9,792, $9,792, and $4,896. If more than 40% of all property you place in service during the year falls in the fourth quarter, the mid-quarter convention replaces the half-year convention and reshuffles those percentages.
Section 179 as an Alternative
Section 179 is another first-year deduction route. For 2026, the maximum Section 179 deduction is $2,560,000, phasing out dollar-for-dollar once qualifying property placed in service exceeds $4,090,000. Solar systems used in the active conduct of a trade or business qualify.
The practical difference is flexibility and limits. Section 179 is picked asset by asset, while bonus depreciation applies to every asset in the class. Section 179 also cannot create or increase a net loss; the deduction is capped at your taxable business income, with any excess carried forward. For most installations in 2026, 100% bonus depreciation is simpler and more useful because it has no income limitation. Section 179 earns its place when you want to expense one specific solar asset without changing the treatment of other property in the same class, or when your state’s tax rules do not conform to federal bonus depreciation.
Recapture if You Sell or Stop Using the System
Aggressive first-year deductions carry a future cost. Selling the system or converting it from business to personal use triggers two separate recapture mechanisms.
Depreciation Recapture Under Section 1245
Solar panels are personal property, not real estate, so any gain on sale is taxed as ordinary income up to the depreciation you previously deducted. If you took $85,000 in bonus depreciation and later sell for $50,000, the entire $50,000 gain is ordinary income rather than capital gain.
Investment Tax Credit Recapture
The ITC vests over five years. If the system stops being investment credit property inside that window, you repay a share of the credit:1Office of the Law Revision Counsel. 26 U.S. Code 50 – Other Special Rules
- Within year 1: 100% recaptured
- Within year 2: 80%
- Within year 3: 60%
- Within year 4: 40%
- Within year 5: 20%
- After year 5: no recapture
Selling three years in on a $30,000 credit means repaying $18,000. The recapture is added to your tax bill for the year of disposition. When the credit is recaptured, your depreciable basis increases by 50% of the recaptured amount, which partially offsets the hit.
Passive Activity Loss Limits Can Suspend Your Deductions
Large depreciation numbers do not always turn into immediate tax savings. If you invest in a solar project but do not materially participate in operating it, the deductions are passive activity losses under Section 469. Passive losses can only offset passive income. They cannot reduce your wages, your active business profits, or your portfolio income.
Material participation generally requires more than 500 hours in the activity per year, or more than 100 hours when no one else participates more. Most passive solar investors, such as limited partners in a solar fund, will not clear those tests. Their deductions and credits sit suspended until they produce passive income from that activity or another passive activity, or until they dispose of the entire interest.
The limitation applies to individuals, trusts, estates, closely held C corporations, and personal service corporations. It does not apply at the partnership or S corporation level, but it does apply when losses flow through to individual partners and shareholders. If the tax benefits are a main reason you are considering a solar investment, run the projected deductions through the passive activity rules first to see whether you can actually use them.
Reporting Solar Depreciation on Your Return
Depreciation deductions, including bonus depreciation elections, go on IRS Form 4562, Depreciation and Amortization.7Internal Revenue Service. Form 4562 – Depreciation and Amortization File Form 4562 for the year the system is placed in service and for any later year you claim depreciation on it. The form captures the placed-in-service date, the initial cost, any bonus depreciation or Section 179 amount, and the remaining MACRS deduction.
The form is required in the placed-in-service year, in any year you claim a Section 179 deduction, and in any year depreciation is claimed on a corporate return other than an S corporation.8Internal Revenue Service. Instructions for Form 4562 – Depreciation and Amortization The total depreciation flows from Form 4562 to the right schedule on your return. A sole proprietorship or single-member LLC pushes it to Schedule C. Solar on a rental property goes to Schedule E. Either way, the deduction reduces net income on that schedule, which reduces adjusted gross income on Form 1040.
Keep every purchase invoice, installation contract, placed-in-service record, and ITC election. The IRS can examine depreciation claims for any open tax year, and the five-year ITC recapture window means your credit eligibility can be reviewed well after you filed the original return.