Solar Panel Tax Credit Calculator

How to use this calculator

The calculator above combines a percentage incentive you have independently verified, a flat state or utility rebate, and gross system cost into a planning net-cost figure. The U.S. percentage defaults to 0% because Section 25D is unavailable for new homeowner expenditures after 31 December 2025.

1. Gross system cost — the cash-equivalent contract price before any incentives. EnergySage’s H2 2025 marketplace data puts the U.S. residential median at $2.49/W, so a 7 kW benchmark is about $17,430 before roof-specific adders.
2. Tax credit (% of cost) — start with 30 for the federal ITC alone. Add your state credit if applicable: New York 25%, South Carolina 25%, Hawaii 35% (capped at $5,000), Massachusetts 15% (capped at $1,000), Arizona 25% (capped at $1,000). Stacking is additive but watch the per-state cap.
3. Additional flat rebate — utility cash rebates and state up-front rebates that arrive as a check, not a tax-return line. New Jersey TREC/SREC II programs, NY-Sun MW Block payments, Mass SMART, Illinois Solar for All, Connecticut RSIP, Long Island PSEG rebate, etc. Cap by program is published on DSIRE.

How the math works

Both incentive types reduce your net cost, but they apply at different points in your tax flow:

percentage_credit = gross_cost × pct/100   (only a verified current program)
flat_rebate       = state_rebate_amount    (received up-front from utility or state)
total_incentive   = percentage_credit + flat_rebate
net_cost          = gross_cost - total_incentive

A 7 kW system at $20,000 with a verified $1,500 utility rebate:

• Federal homeowner Section 25D for a 2026 expenditure: $0
• Verified utility rebate: $1,500
• Net planning cost: $20,000 − $1,500 = $18,500
• Effective discount: 7.5%

Program tax treatment can differ. Read the current administrator terms and ask a qualified adviser how a rebate affects any separate state or business tax basis.

Section 25D — the 2026 termination rule

The IRS states that Section 25D is not allowed for expenditures made after 31 December 2025. For this purpose, an expenditure is generally treated as made when original installation is completed. Keep 2025 invoices and commissioning evidence if you are dealing with a qualifying earlier expenditure or carry-forward, but do not use those documents to create a new credit for a system completed in 2026.

State income-tax credits worth claiming (2026)

The DSIRE database (NC State University) is the authoritative source. The biggest stackable state credits in 2026:

These are tax credits — they reduce your state income-tax liability. Filing requirements vary by state; most use a residential energy credit form attached to the state income-tax return.

Utility rebates and state cash programs (flat-rebate slot)

Programs that pay cash rather than reducing tax. Big ones in 2026:

• NY-Sun (NYSERDA) — MW Block residential incentives, $0.20–$0.50/W depending on region and queue position. Check current block at nyserda.ny.gov.
• Mass SMART — declining-block production-based incentive, paid out per kWh over 10 years. Compensation ranges $0.05–$0.20/kWh by service territory and block.
• NJ SREC-II / SuSI — successor to SREC; pays per MWh produced for 15 years. ~$85/SREC current market.
• Illinois Solar for All / Adjustable Block — guaranteed $0.075/kWh for low-income; market rates for general residential.
• Long Island PSEG Long Island — $300–$400 cash rebate plus net metering.
• CT Residential Solar Investment Program (RSIP) — closed but check Eversource and UI for successor performance-based incentive.
• Austin Energy Solar PBI — $2,500 flat residential rebate plus net metering.
• Sacramento SMUD — production-based incentive plus interconnection rebate.

Battery example for a 2026 homeowner purchase

• 7 kW PV: $20,000
• 13.5 kWh Tesla Powerwall 3: $11,500 installed
• Combined gross: $31,500
• New Section 25D credit for a post-2025 expenditure: $0
• Planning cost before verified state or utility programs: $31,500

If you live in a state with a stackable battery rebate (Mass Connected Solutions pays Powerwall owners $1,000–$2,000/yr to enroll; CA SGIP equity tier pays $850–$1,000/kWh on qualifying batteries), the effective net can drop another 15–30%.

Ownership still changes the analysis

Cash and loan customers own the system; lease and PPA providers generally retain ownership. Third-party owners may have access to business-credit rules that are not available as a personal homeowner credit. Compare the complete contract price, escalator, transfer terms, maintenance obligations and buyout formula rather than assuming a 30% benefit is passed through.

Pair this with the investment tax credit calculator, cost calculator, and payback calculator

The tax credit calculator gives you the static net cost; the payback calculator turns that into break-even years; the cost calculator validates your gross before incentives. Run all three before signing — and verify state and utility programs at DSIRE before plugging numbers in.

Sources

• IRS — 2025 energy-credit termination FAQs — Section 25D termination and expenditure timing
• DSIRE database (NC State University) — every state, utility, and local incentive
• EnergySage Solar Marketplace Report H2 2025 — installed cost-per-watt benchmarks
• SEIA — Solar Investment Tax Credit Resource Page — policy summary and FAQ
• DOE — Homeowner’s Guide to the Federal Tax Credit — qualifying expenditures
• NYSERDA NY-Sun — residential block schedule