What to ask before signing a solar quote
Get three quotes, and compare them on price per watt — not on monthly payment. The spread on identical systems is routinely 30–40%, which is a bigger lever than any equipment choice you will make. These are the questions that expose the difference.
Normalise every quote first
Divide total price by system size in watts. A $21,000 quote for 7 kW is $3.00/W; a $19,000 quote for 6 kW is $3.17/W and is the more expensive one despite the smaller number. The 2026 US average is around $2.85/W before incentives.
The twelve questions
- What is the cash price, and the price per watt? Before any financing discussion.
- Which net metering tariff will I be on, specifically? Not "you'll get net metering" — the tariff name. It drives your return more than the hardware. Why →
- What annual production do you estimate, and from what model? Ask for the shading analysis, not a rule of thumb.
- What degradation rate did you assume? Anything under 0.5%/yr is optimistic.
- What electricity price inflation did you assume? Above 4%/yr is flattering the numbers.
- Who warranties the roof penetrations, and for how long? Leaks are the expensive failure and they are workmanship, not equipment.
- Is the inverter replacement in your projection? String inverters need replacing around year 12–15 at $1,500–3,000. Many projections quietly omit it.
- Are you the installer or a sales dealer? Dealers subcontract; you want to know who actually gets on the roof, and who you call in year six.
- Is my electrical panel adequate, or is an upgrade needed? A service upgrade is $2,000–4,000 and is a common surprise.
- What happens if production falls short of your estimate? Some offer a production guarantee. Most do not — worth knowing which.
- What is the workmanship warranty, separate from the equipment warranty? 10 years is good, 5 is thin, 25 is marketing.
- What is the total cost if I cancel after signing? Ask before signing, not after.
Red flags
- "This price is only good today." Nothing about solar pricing is genuinely time-limited. This is pressure, not a deal.
- A quote with no shading analysis. If they have not looked at your roof, they are guessing at your production.
- Reluctance to give the cash price. Points to margin buried in financing.
- Claims of "free solar." It is a lease or a power purchase agreement. You are trading most of the savings and complicating a future sale.
- Assumed electricity inflation of 5%+. Makes any system look good on a 25-year chart.
- Door-to-door with same-day signing. Legitimate installers are happy to wait a week.
Before the first call
Know roughly what your roof can hold and what it should cost, so you can tell a fair quote from a padded one. Run your address through our checker → It uses Google's aerial imagery, so the shading figure is measured rather than estimated.
What this looks like in real cities
Measured rooftop data, spanning the range from fastest to slowest payback we have found:
| City | Sun hrs/yr | Rate | Payback |
|---|---|---|---|
| Kahului, HI | 1,627 | 42.1¢ | 3.5 yrs |
| McAllen, TX | 1,784 | 15.1¢ | 8.8 yrs |
| Penzance, South West | 1,186 | 26.1¢ | 10.9 yrs |
| Merthyr Tydfil, Wales | 993 | 26.1¢ | 12.9 yrs |
| Trois-Rivières, QC | 1,347 | 7.9¢ | 31.9 yrs |
Frequently asked
How many solar quotes should I get?
At least three. Quotes for the same house routinely differ by thousands, because labour, margin and equipment choices vary far more than hardware cost does. Ask each installer to quote the same system size and panel wattage, otherwise you are comparing different products rather than different prices.
Should I use a national company or a local installer?
Both can be good. Local installers are often cheaper and easier to reach for warranty work; national firms may offer stronger paperwork and longer guarantees. What matters more is how long the company has traded, who honours the workmanship warranty, and whether they will survive to honour it.
Is solar financing worth it?
It depends entirely on the interest rate. A low-rate loan can leave you cash-flow positive from day one, with payments below your old bill. A high-rate loan, or a long term loaded with dealer fees, can cost more than the electricity it saves. Compare total repaid against cash price.
Related guides
General information, updated 2026-08-22. Not financial, tax or engineering advice.