Solar Tax Credit Stacking 2026 Calculator (25D + State Rebate)
The federal Residential Clean Energy Credit (IRC §25D) gives homeowners 30% of solar system cost as a non-refundable credit — but stacking with state and utility rebates affects the credit basis. Calculate your true net cost after all 2026 incentives stack correctly.
| Gross system cost | — |
| Utility rebate (always reduces basis) | — |
| State rebate (basis impact) | — |
| Federal credit basis | — |
| §25D credit rate | — |
| Calculated federal credit | — |
| Credit usable this year (vs liability) | — |
| Credit carried forward | — |
| Net cost after all incentives | — |
| 20-year SREC value | — |
The federal Residential Clean Energy Credit under IRC §25D gives homeowners a 30% non-refundable credit on solar PV, solar water heating, geothermal, and battery storage placed in service before Dec 31, 2025. The One Big Beautiful Bill (OBBB) of 2025 accelerated the credit's sunset — systems placed in service after that date receive 0% federal credit, ending the originally-planned phase-down through 2034.
How §25D Stacks With State and Utility Rebates
Per IRS guidance and §136 of the Internal Revenue Code, utility rebates for energy conservation subsidies are excluded from gross income but reduce the federal credit basis dollar-for-dollar. Non-taxable state rebates also reduce basis. Taxable state incentives (income-based, treated as state grants) do NOT reduce federal basis — you pay state tax on them but keep the full federal credit. SRECs (Solar Renewable Energy Certificates) are taxable income but do not affect §25D basis.
OBBB 2026 Sunset and Timing
The One Big Beautiful Bill enacted in 2025 terminates §25D for property placed in service after December 31, 2025. "Placed in service" generally means installed, inspected, and operational — not just contracted or paid. Homeowners who signed contracts in 2025 but had installation slip into 2026 risk losing the entire 30% credit. Get a final inspection sign-off dated 2025 to preserve eligibility. Battery storage of at least 3 kWh capacity remains separately creditable under §25D as long as placed in service before the same deadline.
Non-Refundable Credit and Carryforward
§25D is non-refundable — the credit can only offset federal tax liability for the year. If your credit exceeds tax owed, the excess carries forward indefinitely (currently no expiration). Retirees with low tax liability often spread the credit across 3-5 years. There is no income cap on §25D — high-earners qualify equally with middle-income taxpayers, unlike the §30D EV credit.
Common Solar Credit Stacking Mistakes
(1) Forgetting to subtract utility rebate from basis — IRS Form 5695 instructions require this. (2) Including loan interest in basis — only the equipment + installation cost qualifies, not financing costs. (3) Claiming credit before placed in service — even if 100% paid, the credit applies in the tax year the system was operational. (4) Missing battery storage — standalone battery storage ≥3 kWh qualifies for 30% under §25D even retrofitted to existing solar. (5) Double-counting state credit — most states give separate state income tax credit; the federal §25D operates independently.
Last updated May 2026. Sources: IRC §25D, §136, IRS Form 5695 instructions, One Big Beautiful Bill (Public Law 119-21, July 2025). Always confirm with a tax professional.