What installers will not tell you (and what to ask)

Most residential solar installers are honest, technically competent, and proud of their work. Most of them are also salespeople. The friction between "I want this customer to make the right call" and "I need to close this deal so my truck rolls next week" produces predictable patterns in how quotes are presented, what's in the contract, and what gets quietly omitted. Here is what to look for, what to ask, and what to never sign without changing.

By The Solar Brief Editorial Team  ·  Updated May 2026

The "lifetime savings" number is a marketing number

Almost every quote you receive will lead with a lifetime-savings figure: "$67,000 over 25 years," "saves you $112,000 over the life of the system," and so on. These numbers depend on at least four assumptions stacked on top of each other: (1) annual electricity rate inflation, (2) system production degradation, (3) what the homeowner does with the bill credits, and (4) the number of years the system actually operates at advertised capacity. Change any one of those by a percentage point and the lifetime number swings by tens of thousands.

The number you can trust, and the only one you should compare across quotes, is cash payback period in years — how many years until the system has paid for itself in displaced electricity, before any speculation about future rates. After that the production is upside, but how much upside is unknowable 20 years out. Ask every installer for the cash payback assuming today's electricity rate, no rate inflation. The number that comes back is the comparable one.

"Tier-1 panels" doesn't mean what you think

"Tier-1" is a financial classification used by Bloomberg New Energy Finance to indicate panel manufacturers considered bankable by lenders. It's a financial-risk rating, not a quality rating. There are panels in the Tier-1 list that are perfectly good and panels in the Tier-1 list you would not want on your roof.

Always ask for the specific panel make and model number in the contract — not "tier-1 mono panels," not "high-efficiency 400W panels," not "premium German engineering." A specific make and model means the installer is committing to install exactly that panel. A vague descriptor means they reserve the right to substitute whatever they have in the warehouse. Q Cells Q.PEAK DUO, REC Alpha Pure, Panasonic EverVolt, Silfab Prime, and SunPower Maxeon are all reasonable mid-to-premium choices in 2026. The brand matters less than the specificity.

Production estimate vs. nameplate capacity

An 8 kW system has a nameplate capacity of 8 kW. The kilowatt-hour production it actually delivers in a year depends on roof orientation, shading, latitude, soiling, panel type, inverter efficiency, and weather. Two installers can quote you the same 8 kW system with production estimates 1,500 kWh apart — and the higher number is sometimes wishful, not technical.

Ask for the annual production estimate in kWh per year, modeled by the installer's design software (typically Aurora Solar, Helioscope, or PVsyst). Ask which model they used and whether the production estimate accounts for shading from the trees they walked past on the way to your front door. A reputable installer will share the model output. A reluctant one will tell you "we use industry-standard assumptions." That's a signal.

The clauses to read

Production guarantee

Some installers guarantee a minimum annual kWh production for the first 1, 5, or 10 years. If actual production falls below the guarantee, they pay you the difference at retail rate. This is a real consumer protection — and a signal the installer believes their own production estimate. If a quote includes no production guarantee at all, ask why. The answer "we don't offer that" is fine; the answer "we don't think those are necessary" is a flag.

Workmanship warranty

Separate from the panel warranty (typically 25 years from the manufacturer) and the inverter warranty (typically 12 years), the workmanship warranty covers the install quality — leak-free roof penetrations, correct mounting, correct wiring. This is the one most likely to come due in years 5 to 15 when the original installer may or may not still be operating.

A 1-year workmanship warranty is meaningfully worse than 10 years. A 10-year workmanship warranty is meaningfully worse than 25 years. The installer's confidence in their own work shows up here. We see workmanship warranties ranging from 2 to 25 years across our partner network; 10 years is a reasonable floor for a serious purchase.

Roof warranty integration

If your roof has an existing manufacturer warranty (most asphalt-shingle roofs do, for 20–50 years), drilling penetrations into it can void the warranty unless the installer is on the roofer's approved list, OR uses an approved racking system, OR installs to a documented spec the roofer accepts. Ask the installer how they protect your existing roof warranty. If they shrug, that's a problem you'll discover in 8 years when you have a leak and the roofing company says "those panel installers voided your warranty."

Cancellation clause

Most state consumer-protection laws require a 3-day cancellation window after signing. Some states require 5 or 7. Look for the clause that says "you may cancel within X business days of signing this contract" and verify the X matches your state's law. Look also for any clause that says you owe a percentage of the contract value if you cancel between signing and install — that should be zero in the cancellation window, with reasonable cost recovery (permitting fees, design fees) if you cancel after design work is complete.

Lien rights and lender language

Some solar contracts contain language that gives the financing lender a security interest in your home (a lien) until the loan is paid off. Read this carefully. A UCC-1 filing on the equipment is normal and shouldn't worry you. A blanket lien on the property is unusual and should be negotiated out unless you're explicitly comfortable with it. If you're financing with a third-party lender (Sunlight, GoodLeap, EverBright, Mosaic), the lender's terms are separate from the install contract — read both.

Five questions that turn a generic quote into a specific one

If you ask only five questions during a quote conversation, ask these:

1. What's the specific panel make and model, and the specific inverter make and model? If the answer is vague, the contract will be vague.

2. What's your modeled annual production in kWh, and what software did you model it in? Ask for the file or a screenshot. The good ones share it.

3. What's the workmanship warranty length, and is the company that issued it the same company that's installing? Some installers white-label the warranty through a third party that may or may not exist in 10 years.

4. Is the federal ITC line in the quote a deduction from price, or is it a calculation of what I'll claim on my taxes separately? Always the latter. If the quote subtracts the ITC from the price as if it's a coupon, that's a misleading framing — you owe the full price to the installer and claim the ITC on your own taxes.

5. What happens if the production guarantee isn't met in year 3? Listen for a specific dollar mechanism. "We'll come look at it" is not a mechanism.

What "tier-1 panels with industry-leading warranties" actually means

It means: the salesperson does not want to commit to specifics. Marketing language that survives the first conversation tends to survive the contract too. If the quote you're handed reads like a brochure rather than a specification, push back politely once, then walk if you don't get specifics. You don't owe an installer your business because they showed up on a Saturday.

A quick word on door-knockers

Door-to-door solar sales — the rep who shows up unannounced and offers a "neighborhood discount" if you sign tonight — is the single most pressure-driven channel in this industry. We don't have data showing those installs are systematically lower quality than other channels, but we have plenty of complaint volume showing they're systematically more expensive than the same install bought through a quote-and-compare process. The "neighborhood discount" is almost always priced into the headline number to make the discount real.

If a door-knocker shows up: thank them, take their card, and tell them you'll call back next week. Then get two other quotes. If they pressure you to sign tonight, that's a strong signal not to.

The honest summary

Most installers will give you a fine system at a fair price if you ask the right questions and read the contract carefully. The problems happen when homeowners trust the lifetime-savings number, accept "tier-1 panels" as a specification, and sign in the same conversation they first heard the pitch. Slow down, get three quotes, ask for specific make/model and modeled production, read the warranty, and you'll filter out 95% of the bad outcomes before they happen.