Most residential solar equipment is good. Panels from established manufacturers all perform within a narrow band, and inverters are mature products. What varies enormously is who mounts them on your roof, who pulls the permit, and who is still around in year eight when something needs attention. These are the questions that surface that.

About the company

1. Are you the installer, or do you subcontract the installation? Many solar companies are sales organizations that contract the physical work to a crew you will never meet. That is not automatically bad, but you should know it, and you should know which entity your warranty runs against.

2. How long has this specific legal entity been operating? Not the brand, the entity on the contract. Solar has a high rate of company turnover, and a twenty-five year workmanship warranty from a company three years old is a statement about intent, not about certainty.

3. What licenses do you and your electrician hold? The electrical work requires a licensed electrician. Ask for the license number and verify it with the state licensing board. It takes two minutes online.

4. Can I see three installations in my area from more than two years ago? Recent references show the sales process worked. Older references show whether the installation held up and whether the company answered the phone afterward.

About the roof

5. How old is my roof, and what do you recommend? A competent installer will tell you if your roof needs replacement first. Removing and reinstalling an array to reroof later is a real expense that a good installer will warn you about rather than let you discover in five years.

6. What mounting and flashing method do you use? You want a specific answer describing a flashed mount that integrates with the roofing material, not a sealant-only approach. Ask what happens if a mount leaks: who pays for the roof repair and the interior damage, and is that in writing.

7. Will you provide a structural assessment? Some jurisdictions require an engineer's letter confirming the roof structure can carry the added load. Ask whether yours does and who provides it.

8. Does the array go on any face I have not agreed to? Get the panel layout drawing and confirm it matches what you discussed, particularly for north faces and street-facing elevations.

About the system

9. What is the shade analysis, per panel? Ask for the per-panel solar access percentage from whatever modeling tool they used. If several panels are heavily shaded, ask why they are in the design at all.

10. String inverter, microinverters, or optimizers, and why for my roof? Each is a legitimate choice. Microinverters and optimizers handle partial shading and multiple roof orientations better and give per-panel monitoring. String inverters are simpler and cheaper with a single unshaded orientation. The reasoning matters more than the answer.

11. What monitoring will I have, and is it included after year one? You want per-panel or at minimum per-string visibility, and you want to know whether the monitoring subscription has an ongoing cost.

About warranties, which are three separate things

12. Walk me through all three warranties. There is a panel warranty from the manufacturer, typically 25 years on power output and shorter on the product itself. There is an inverter warranty, commonly 10 to 25 years depending on type. And there is a workmanship warranty from the installer covering the labor, mounting, and roof penetrations.

Ask specifically: if a panel fails in year twelve, the manufacturer may ship a replacement panel, but who pays the labor to remove and reinstall it? If the answer is you, the 25 year warranty is less than it sounds. Ask whether labor is covered and for how long.

13. Is the workmanship warranty transferable to a buyer, and how? Get the process in writing, including any transfer fee.

About the paperwork

14. Who handles permitting, inspection, and utility interconnection, and what are current timelines? Permitting and interconnection are where projects stall. You want the installer to own both, and you want written estimated timelines so you can tell when something has gone quiet.

Also ask what happens if the utility denies or delays interconnection: is there a deposit at risk, and can you cancel.

Two documents to insist on

A complete contract before deposit, with equipment model numbers, panel count, system size, layout drawing, total price, payment schedule, and estimated year-one production. And a written cash price alongside any financed price, so you can see what the financing costs.

Finally, be skeptical of urgency. A discount that expires this evening, an incentive that is claimed to be ending imminently, or a signature requested at the kitchen table on the first visit are all sales technique. A real solar project is a twenty-five year commitment to your roof, and every legitimate installer will still be there in a week.