Before signing a contract with a solar installer, ask for a written, itemized proposal that spells out system size, expected production, all equipment brands and model numbers, the full price with every add-on, financing terms if any, warranty lengths, and who is responsible for permits and utility paperwork. Ask how the production estimate was calculated and what happens if the finished system underperforms it. If a company won’t put these details in writing before you sign, that alone is worth pausing over.
Solar quotes can look similar on the surface — a panel count, a price, a projected output — while differing enormously underneath in equipment quality, workmanship, and what’s actually included. The questions below are meant to help you compare proposals on substance rather than presentation, not to tell you which system or company to choose.
Start with the proposal itself, not the pitch
A sales presentation is not a contract. Before you sign anything, ask for the actual proposal document you’ll be bound by, and read it independent of whatever slideshow or app was used to sell you. Specifically:
- What is the exact system size in kilowatts, and how many panels of what wattage does that require?
- What annual production (in kilowatt-hours) is the estimate based on, and what assumptions — roof angle, shading, local weather data — went into that number?
- Is the price in the proposal the final, all-in price, or are permits, inspections, utility fees, or a specific roof condition (like existing shading or an older roof) going to change it later?
If you want to understand the mechanics behind these numbers before you evaluate a quote, our explainer on how solar panels actually work walks through how sunlight, panel orientation, and inverter type affect real-world output — useful context for judging whether a company’s production estimate seems reasonable for your roof.
Ask about the equipment, not just the brand names
Two systems can use panels from the same manufacturer and still perform differently depending on the inverter type, mounting hardware, and how the array is laid out. Questions worth asking include:
- What panel and inverter models are specified, and what are their manufacturer warranty terms — separately for the panels and for the inverter, since they’re usually different?
- Is this a string inverter, microinverters, or a hybrid setup, and why did the installer choose that configuration for your roof?
- What is the workmanship or labor warranty from the installer itself, separate from the manufacturer warranties on the parts — and does it survive if the company is later sold or goes out of business?
- Is the equipment being installed new, and can the installer confirm it isn’t refurbished, discontinued, or an overstock model being cleared out?
Warranty length and coverage vary by manufacturer and by installer, and the fine print on what voids a warranty (unauthorized repairs, certain roof types, lack of maintenance) matters as much as the headline number.
Ask who is licensed, insured, and doing the actual work
Installer licensing requirements differ by state, province, and even municipality, so this is not a one-size answer. Before signing, ask:
- Is the company licensed to do electrical and roofing work in your specific jurisdiction, and can they provide license numbers you can verify with the relevant licensing board?
- Are they carrying liability insurance and worker’s compensation coverage, and can you get proof of that in writing?
- Will the crew that shows up be direct employees, or subcontractors — and if subcontractors, who is legally responsible if something goes wrong during installation?
- Who pulls the building permit and schedules the inspection, and is that cost included in the quoted price?
Ask about interconnection and your utility
A rooftop system generally can’t legally operate connected to the grid until your utility approves the interconnection application and, in most areas, a net metering or similar agreement is in place. This process and its rules vary significantly by utility territory. Ask the installer:
- Who submits the interconnection application, and roughly how long has that utility been taking to approve applications recently?
- What net metering or export compensation program applies in your area, and is the installer assuming a program that might change before your system is turned on?
- Will the system be able to operate at all, or produce any savings, before that utility approval is complete?
Because utility programs and rules shift, it’s worth confirming current terms directly with your utility rather than relying solely on what’s stated in a sales proposal.
Ask about price, incentives, and financing — and get it in writing
This is where the most money is at stake, and also where the most misleading numbers tend to appear. A few ground rules for this conversation:
- Ask for the total cash price of the system before any incentives are applied, and a separate line showing what incentives the installer believes apply — with a note that eligibility and program value should be confirmed with the official program administrator, since incentive rules and amounts change and vary by location.
- If financing is offered, ask for the full loan or lease terms in writing: interest rate, length, whether there’s a balloon payment, and what happens to the loan or lease if you sell the house before it’s paid off.
- Ask whether the installer’s price assumes you’ll qualify for a specific tax credit or rebate, and what the price becomes if you don’t qualify or the program changes before your system is installed.
- Ask whether there are any liens placed on your home as part of the financing, and what that means if you refinance or sell.
Databases like the U.S. Department of Energy’s DSIRE incentive database can help you see what categories of programs exist in your state, but the installer’s proposal is not the place to confirm a specific dollar figure — that comes from the program administrator or your utility directly.
Ask what happens after the panels go up
Installation day is not the end of the relationship — or shouldn’t be. Ask:
- Is there a monitoring system included, and who is responsible for noticing and responding if production drops unexpectedly?
- What maintenance, if any, does the system need, and is anything like panel cleaning or inverter servicing included or excluded from the price?
- What is the process if a panel or inverter fails under warranty — does the installer handle the claim, or is that on you?
- Does the installer offer any post-installation inspection or performance check, and for how long after installation?
A quick reference for comparing proposals
| Category | What to request in writing |
|---|---|
| System design | Size, panel/inverter count, production estimate and its assumptions |
| Equipment | Exact model numbers, manufacturer warranty terms |
| Labor | Workmanship warranty length and what voids it |
| Permits & utility | Who files what, current utility interconnection timeline |
| Price | All-in cash price separate from any incentive assumptions |
| Financing | Full loan/lease terms, liens, transfer-on-sale terms |
If you’re still early in researching whether solar makes sense for your situation at all, our Solar Energy section covers the broader landscape — from how panels work to the policy and technology context — which can help you walk into installer conversations with a clearer sense of what questions matter for your specific home before any proposal lands in front of you.
Frequently asked questions about solar installer questions
What questions should I ask a solar company before signing a contract?
Ask for the exact system size, production estimate basis, equipment model numbers and warranty terms, an all-in price separate from assumed incentives, who handles permits and utility interconnection, and the installer’s own workmanship warranty — all in writing, not just verbally described.
How do I know if a solar quote is legitimate?
Check that the company can provide verifiable licensing and insurance for your jurisdiction, a detailed written proposal rather than a vague estimate, references or a physical business address, and terms that don’t pressure you to sign immediately to “lock in” a price or incentive.
What should be included in a solar installation contract?
A solid contract typically spells out system specifications, total price, payment schedule, permitting and inspection responsibilities, production estimates and how they were derived, equipment and workmanship warranty terms, and a clear timeline — confirm what’s standard in your area with a licensed local professional.
Can a solar installer guarantee my energy bill savings?
Reputable installers generally avoid guaranteeing specific savings because output depends on weather, utility rates, and household usage, all of which change. Ask instead how they calculated their production estimate and what utility rate assumptions they used, and verify current rates with your utility.
Do I need a permit before installing solar panels?
Most jurisdictions require a building and/or electrical permit for rooftop solar, along with utility approval before the system can be connected to the grid. Requirements vary by city, county, and utility, so confirm the process with your local permitting office and your utility directly.
Related reading
Community Solar Explained: How It Works, Solar Panel Efficiency and Degradation Over Time, Rooftop vs Ground-Mount Solar: What Actually Differs.
The Cleaner Energy publishes general information about clean energy technology, not financial, tax, legal or engineering advice. We are writers and editors, not installers, contractors or financial advisers. Incentives, rebates, utility rates and equipment costs vary by location and change over time — confirm current figures with the official program administrator, your utility, or a licensed local professional before making a purchase or installation decision.