The Federal Solar Tax Credit: Check It Before You Sign

The federal solar tax credit reduces what a system costs you, and it is the most misquoted number in a solar pitch. It is a credit against tax owed rather than a rebate, its rate is set by federal law that has changed more than once, and it is only one of the four things that decide whether an array is a good purchase.

This is a checklist rather than a sales case. Work through it before a quote turns into a contract, because every item on it is easier to verify beforehand than to unwind afterward.

A credit is not a rebate

This is the distinction that causes the most disappointment.

A rebate is money sent to you. A credit reduces the federal income tax you owe. If your liability for the year is smaller than the credit, you do not capture the whole of it in that year, and how any remainder is treated depends on the rules in force.

Households on fixed incomes, retirees, and anyone whose withholding already lands them near zero are the ones most likely to find that the number on the sales sheet is not the number in their own return. A salesperson subtracting the full credit from the price in front of you is making an assumption about your tax situation that they have no way to verify.

Ask a tax professional what your own liability looks like. That conversation costs very little and it happens before the contract rather than the following April.

Look up the rate yourself

The residential clean energy credit has been created, allowed to lapse, revived and revised. Its rate has stepped down and back up across different periods, and eligibility rules have moved with it.

So the only reliable source is the IRS page for the tax year in which the system is placed in service, not the year the contract is signed. Those can be different years on a project that runs long, and which one applies is worth pinning down in writing.

A percentage printed in a sales deck is a claim about federal law made by a company with an interest in the answer. Treat it as a starting point for your own check.

Compare quotes before incentives, in dollars per watt

Here is the discipline that makes three solar quotes comparable.

Ask each company for two things: the system size in kilowatts, and the gross price before any credit or incentive. Divide the second by the size in watts. That price per watt is the number you rank.

A larger system costing more is not a worse deal, and a smaller one costing less is not a better one. Without normalizing by size, you are comparing a total for one quantity of equipment against a total for another, which tells you nothing.

Do this before you look at monthly payments. A payment is the output of a financing decision, and a long enough term makes almost any price look manageable.

The number that beats the credit: what exported power is worth

If you only verify one thing on this list, make it this one.

Net metering and interconnection terms decide what a kilowatt hour is worth when your array produces it and the house is not using it. Under full retail net metering that exported unit offsets a unit you would otherwise buy. Under a low export rate it is worth a fraction of that.

Same panels, same roof, same installer, completely different payback. And these rules are set by state regulators and utilities rather than nationally, which means the arithmetic in a national sales presentation may have nothing to do with your address.

Ask the utility directly, in writing. Ask which tariff applies, whether it is locked for a term, and what happens to existing customers if the tariff changes. Then ask the installer to show their production and savings estimate using that tariff rather than a generic one.

Size the system to your bills, not to the roof

Pull twelve months of electricity bills and total the kilowatt hours. That number, not the available roof area, is the starting point for sizing.

A system built well past your consumption produces power you may be credited very little for, depending on the answer to the previous section. Oversizing is a common way for a project's price to grow without its payback improving.

Ask for the production estimate and the shading analysis behind it. Then compare estimates across bidders for the same roof. Where one company's projection is far above the others, that gap is information about the company rather than about your roof.

Do the roof first

An array on a roof with a few years left creates a bill nobody plans for. When the roof gets replaced, the panels have to come off and go back on, and that removal and reinstallation is not cheap.

If the roof is near the end, replace it first and mount the array second, even if that delays the project by a season. It is one of the few sequencing decisions in home improvement where the right order is not debatable, and our roof replacement cost guide covers how to tell where a roof actually stands.

While the array is being designed, ask where the penetrations go, how they are flashed, and whose warranty covers a leak at a mount. That last question has a habit of producing a pause.

Read the financing as carefully as the equipment

Cash, a loan, a lease and a power purchase agreement are four different products with four different risk profiles, and only the first two leave you owning the system.

On a loan, look for the dealer fee built into the price, which is often the reason a cash price and a financed price differ. Look at what happens to the payment if you do not apply the tax credit to the principal within a set window, because some loan structures assume you will.

On leases and power purchase agreements, the two clauses that cause regret are the annual payment escalator and the transfer terms when you sell the house. A buyer who does not want to assume the agreement is a problem you inherit at closing.

When to skip it

Four situations turn a good product into a poor purchase, and none of them is a criticism of solar.

A heavily shaded roof will not carry a payback, and optimizers reduce the penalty rather than removing it. A short remaining stay in the house means somebody else collects the savings you paid for. A utility that pays very little for exports stretches the payback past the point most people care about. And a household without the federal tax liability to use the credit is buying at a higher effective price than the pitch described.

Where none of those applies, and the roof is sound, and the export tariff is favorable, solar is one of the more straightforward purchases on this site. The full set of variables, including how to read a production estimate, is in our solar panel installation cost guide.

If the goal is simply a lower bill rather than an array specifically, the cheap work comes first: air sealing, insulation, and the equipment that runs the most hours. Generating power to run a leaky house is the most expensive order to do things in.