Solar Panels in 2026: How Many You Need Now That the Federal Tax Credit Is Gone

A neighbor of mine got three solar quotes in the spring of 2025 and sat on all of them. By the time he was ready to sign, the federal tax credit that made the numbers work — a straight 30% off the total cost — was gone. The 2025 tax law that Congress passed that summer ended the residential clean energy credit for any system placed in service after December 31, 2025. He'd missed it by about six months, and the installer's follow-up quote was nearly $7,000 higher for the exact same system.

If you're pricing out solar in 2026, you're doing the math without a discount homeowners have leaned on since 2006. That doesn't mean solar stopped making sense — it means the arithmetic changed, and you need to redo it honestly instead of trusting a sales pitch built on last year's numbers. This article walks through exactly how many panels a typical home needs and whether the payback still works without the credit, using the same formula behind the Solar Panel Calculator.

What Actually Changed: The Federal Tax Credit Expired

The Residential Clean Energy Credit (IRS Section 25D) let homeowners deduct 30% of the cost of a solar installation from their federal tax bill. The 2025 tax reconciliation law ended that credit for any residential solar, battery, or geothermal system placed in service after December 31, 2025 — cutting off an incentive that had applied, in some form, since the Energy Policy Act of 2005.

For a typical $24,000 system, that credit was worth roughly $7,200 — often the difference between a 9-year payback and a 13-year one. Losing it doesn't erase solar's value, but it does mean every "solar pays for itself in 7 years" claim you read before 2026 needs to be re-run with current numbers, not assumed.

Two things are still true, and worth separating from the federal credit:

• Many state and utility incentives are untouched. State tax credits, property tax exemptions for the added home value, and utility rebates are set independently of federal law and still apply in dozens of states.
• Net metering still exists in most markets, crediting you for excess electricity your panels send back to the grid — though the rate you're credited varies enormously by utility.

How Many Solar Panels Do You Actually Need?

Before you can price a system, you need to size it — and that's just three numbers plugged into one formula.

Peak sun hours is a standardized measure of how much usable sunlight a location gets per day, averaged over the year — not the same as daylight hours. A "peak sun hour" is one hour during which sunlight intensity averages 1,000 watts per square meter. Most of the continental US sees between 3.5 and 6.5 peak sun hours a day depending on climate; the UK averages closer to 2.8–3.2 because of higher latitude and cloud cover.

Worked example — US household: A home with a $150/month electricity bill at the US average rate of $0.17/kWh, in a region averaging 4.5 peak sun hours, with a system efficiency of 80% (accounting for inverter losses, wiring, and panel heat):

• Monthly usage: $150 ÷ $0.17 = 882 kWh
• System size: 882 ÷ (4.5 × 30 × 0.80) = 882 ÷ 108 = 8.2 kW
• Panels needed (400W each): 8,200 ÷ 400 = 20.5 → 21 panels

Worked example — UK household: A home with a £120/month bill at the UK average of £0.26/kWh, in a region averaging 3.0 peak sun hours:

• Monthly usage: £120 ÷ £0.26 = 462 kWh
• System size: 462 ÷ (3.0 × 30 × 0.80) = 462 ÷ 72 = 6.4 kW
• Panels needed (400W each): 6,400 ÷ 400 = 16 panels

That's the same formula the Solar Panel Calculator runs automatically from your bill, local sun hours, and panel wattage — worth using instead of hand-typing this into a spreadsheet, since a small change in efficiency assumption shifts the panel count noticeably.

Does Solar Still Pay for Itself Without the 30% Credit?

This is the question that actually matters now. Let's finish the US example above and run it both ways.

The National Renewable Energy Laboratory's (NREL) annual cost benchmark has put typical US residential solar installation costs in the range of $2.50–$3.50 per watt before incentives in recent years. Using $3.00/watt on our 8.2 kW system:

Losing the credit added roughly four years to the payback period on this system — a meaningful change, but not one that erases the case for solar, especially given that panels are typically warrantied for 25 years and keep producing well beyond their payback point.

Worked example — UK, no federal-style credit either way: UK solar has never had a federal tax credit in the US sense, but installations have carried 0% VAT (rather than the standard 20%) since April 2022. A 6.4 kW system at a typical UK installed cost of roughly £1,600–£2,000 per kW comes to about £10,240–£12,800, with no VAT added. Against annual savings of roughly £120 × 12 = £1,440 (assuming full offset), payback lands around 7–9 years — often faster than the post-2025 US figure, because UK installation costs per kW tend to run lower and the VAT relief applies automatically at the point of sale rather than as a credit you claim later.

What Still Makes Solar Worth It in 2026?

Four factors change the payback math in solar's favor even without the federal credit, and they're worth checking before writing solar off:

1. State-level incentives are independent of federal law. States including New York, Massachusetts, and Illinois run their own tax credits, rebates, or performance-based incentive programs (like SRECs) that were unaffected by the 2025 federal change.
2. Electricity rates keep climbing. A payback calculation assumes a flat electricity rate, but US residential rates have risen most years this decade. Every rate increase after installation is pure upside for a system you've already paid for — solar locks in your rate at today's number for panels that keep producing for decades.
3. Home value. Multiple real-estate studies have found solar-equipped homes sell at a premium in most US markets, and in many states that added value is explicitly exempt from a property tax reassessment.
4. Battery storage changes the equation where net metering rates are weak. If your utility only credits excess solar at a low rate, pairing panels with a battery lets you use more of what you generate yourself instead of selling it back cheaply.

A solar payback period is the number of years of energy savings it takes to recover the net cost of a system after all incentives — it does not account for the 15–25+ years of largely free electricity that typically follow, which is the actual return on the investment, not just the breakeven point.

Before committing to a system size, it's worth sanity-checking the electricity side of your bill too. The Electricity Cost Calculator shows exactly which appliances drive your usage, and the BTU Calculator helps you avoid oversizing an air conditioner — cutting the baseline usage a solar system needs to offset in the first place.

Frequently Asked Questions

Try It Yourself

The federal credit is gone, but the math still favors solar in plenty of markets — the only way to know if yours is one of them is to run your actual bill through the numbers instead of trusting a sales quote.

Use the Solar Panel Calculator to estimate your system size, panel count, cost, annual savings, and payback period from your own electricity bill.

Also worth checking:

• Electricity Cost Calculator — see exactly what's driving your bill before you size a system to offset it
• BTU Calculator — right-size your air conditioning so you're not oversizing solar to cover an inefficient unit