Thinking About Rooftop Solar Panels? Here's What to Know Before Signing a Contract

A rooftop solar panel quote usually leads with three numbers: system size, price per watt, and projected annual savings. Those numbers matter. But they’re not the whole picture, and they’re not what determines whether you’ll be happy with the system in year ten.

The things that cause problems later—a roof that needs replacement before the panels do, a contract that doesn’t clearly state who pays for removal and reinstallation, payment terms you didn’t fully understand—often aren’t on the first page of the quote. They’re in the fine print, or they’re not written down at all.

This is a checklist for homeowners who are close to signing but want to make sure they’ve asked the right questions first. It doesn’t cover how solar panels work or which equipment is best. It covers what to verify before you commit.

Check Your Roof First

How old is your roof? Has it had leaks, damage, or repairs? These are the first questions, because solar panels may remain in use for decades, while other parts of the system—and the roof beneath it—may need attention sooner.

If your roof is likely to need repairs or replacement while the panels are installed, the solar panels may need to be removed and reinstalled. That’s a real cost, and someone has to pay it. Ask whether the installer has assessed your roof’s condition and whether any work is recommended before installation. If the roof needs work later, who pays for removing and reinstalling the panels? Make sure the contract addresses this clearly. If it doesn’t, get the answer in writing before you sign.

Understand What the Quote Includes

A quote that looks lower than the others may not include the same scope of work. Before comparing prices, compare what’s actually included.

Does the quote cover the rooftop solar panels, inverter, mounting hardware, labor, permits, and any necessary electrical upgrades? Or are some of those billed separately? Ask your installer: What costs are not included in this quote? Please list them in writing.

Different installers may present quotes differently—one includes permit fees, another doesn’t; one includes an electrical panel upgrade, another treats it as an add-on. Comparing total prices without comparing scope can lead you to the wrong conclusion.

Ask How the Generation Estimate Was Calculated

Most quotes include a projected annual electricity output and a projected savings figure. Those are estimates, not guarantees. Ask how they were calculated.

Did the output estimate account for your roof’s orientation, tilt, shading from trees or nearby buildings, and local weather patterns? Was it based on a site visit or remote imagery? Remote estimates can be useful, but a complex roof or local shading may call for a closer look.

Ask your installer: What assumptions went into this generation estimate? Can you show me how it was calculated?

Then look separately at the savings estimate. What electricity prices does it assume? How much of the solar power does it expect you to use at home, and what value does it assign to electricity sent to the grid? Those assumptions depend on your location and utility arrangement. A reasonable output estimate doesn’t automatically make the savings figure accurate.

Also ask whether the contract includes a production guarantee. A projection and a guarantee are not the same thing. If there’s a guarantee, check what output it covers, over what period, what exclusions apply, and what remedy—if any—the contract provides if output falls short. If there’s no guarantee, know that before you sign, not after.

Read the Contract Carefully

The contract is where the details live, and where disputes are resolved. A few things to confirm:

Equipment. Are the brand and model of the panels, inverter, and mounting hardware written into the contract? “Tier-one brand” is not specific enough. You want model numbers.

Warranty. What does the product warranty cover, and for how long? What does the workmanship warranty cover? Are there exclusions? If you sell the house, does the warranty transfer to the new owner?

Service. If something goes wrong, who do you contact? What’s the response process?

Cancellation. What are the terms for canceling the contract? Are there fees? Any cancellation rights may also depend on local law.

Payment structure. This is often the most consequential part and the least examined. Is this a cash purchase, a loan, a lease, or a power purchase agreement (PPA)? Available options vary by location. If it’s a loan, what are the term, interest rate, and any fees? If it’s a lease or PPA, what are the long-term payment obligations, including any scheduled increases? What happens if you sell the house before the term ends—can the agreement transfer, and are there fees or other conditions? Ask your installer to walk you through the payment terms in plain language and confirm them in writing.

Before signing, check that the written terms match what you’ve been told about equipment, warranties, service, payments, and future roof work.

Check the Installer

A low quote from an installer who won’t be around to handle future problems isn’t a bargain. Ask about qualifications, insurance, and track record.

Does the installer hold the licenses required where you live? Do they carry appropriate liability and worker coverage? Can they provide examples of recent local projects? Are there public reviews you can read? What’s their process for handling service calls after installation? Licensing and insurance requirements vary by location, so check the rules that apply to your project.

Ask your installer: Can you provide references from recent local projects, or point me to public reviews of your work? How do you handle warranty service?

If the installer is evasive about licensing, insurance, or past work, that’s a signal to look elsewhere.

Think About Future Needs

The system you install today should match not just your current electricity use, but your likely future use.

Are you planning to buy an electric vehicle? Add air conditioning? Install a home battery? If any of those are on the horizon, ask whether the proposed design could accommodate them, or what an upgrade would involve. Expanding a system later may cost more than planning for those needs now, though installing capacity you won’t use may not make financial sense either.

Ask your installer: If my electricity use increases, can this system be expanded? What would that involve?

Before You Sign: A Practical Checklist

• Roof condition checked? If roof work is needed later, are removal and reinstallation responsibilities clear in the contract?
  
• Quote scope confirmed in writing? Any excluded costs listed?
  
• Generation estimate explained? Savings assumptions reviewed? Production guarantee—if any—clearly defined?
  
• Equipment models, warranty terms, service responsibilities, and cancellation conditions in the contract?
  
• Payment structure fully understood? Term length, interest or scheduled increases, and transfer requirements clear?
  
• Installer’s licenses, insurance, local project examples, and public reviews checked?
  
• Future electricity needs considered? Do you know whether expansion is possible?

If any of these is unclear, ask the installer and get a written answer before signing. Verbal assurances are not enough. The contract should reflect what you’ve agreed to.

The Bottom Line

A contract for rooftop solar panel is a long-term commitment. The price per watt is only one part of it. The roof’s condition, the scope of the quote, the assumptions behind projected savings, the payment terms, and the installer’s track record all affect whether the system delivers what you expect—or creates problems you didn’t anticipate.

Spend the time to verify these before signing. It’s cheaper than discovering them later.