How to Choose a Solar Installer

The installer matters more than the equipment. Panels are mass-produced to tight tolerances; installations are done by people on your specific roof, and that's where the quality difference and the long-term risk sit.

How do you screen a solar installer?

Licensing. Confirm the appropriate electrical and contractor licensing for your jurisdiction, and verify it through the state's lookup rather than taking their word.

Insurance. General liability and workers' compensation. Roof work carries real risk and you don't want it landing on you.

Local track record. How long have they operated in your area, and can they point to installations nearby? A local firm knows your jurisdiction's permitting and your utility's interconnection process, which directly affects your timeline.

A site visit before quoting. A firm price produced from satellite imagery alone misses roof condition, structure and much of the shading. Treat it as a sales number rather than an engineering one.

How do you compare solar production estimates?

More than anything else, the quality of the production estimate reveals whether you're dealing with engineers or salespeople.

A good estimate:

• Uses location-specific irradiance data for your address
• Models each roof plane separately with its actual azimuth and tilt
• Incorporates a site-specific shading analysis, modelled across the whole year
• Applies and states a system derate for inverter losses, wiring, temperature, soiling and mismatch
• Accounts for clipping if the array is oversized relative to the inverter
• Gives monthly figures, not just an annual total
• Compares against your actual usage from twelve months of bills

A poor estimate gives one annual number with no stated assumptions.

If the estimate doesn't mention shading on a roof with obvious obstructions, or quotes production with no derate, the number is optimistic and your payback math is built on sand. See peak sun hours explained, how shading affects solar panels, and DC-to-AC ratio and clipping.

What should a solar workmanship warranty cover?

The most important contractual term, because installation problems — especially roof penetrations — are more common than panel defects and they damage your house rather than just your output.

Ask specifically:

• How long is it?
• Does it cover roof leaks at penetrations, and for how long?
• Does it cover labor for warranty replacement of panels and inverters? Manufacturer warranties often cover the part only.
• Is it transferable if you sell?
• What backs it if the company ceases trading?

Terms vary enormously between installers, and that variation is one of the most meaningful differences between two otherwise similar proposals.

See solar panel warranties explained and solar racking and mounting systems.

Will my solar installer still exist in ten years?

An uncomfortable structural issue worth naming.

Your workmanship warranty is only worth something if the installer exists to honour it. Manufacturer warranty claims are also normally administered through the installer.

The residential solar industry has seen substantial company turnover. So:

Company stability is part of the warranty evaluation, not separate from it. A shorter warranty from an established local firm can be worth more than a longer one from a company with no track record.

Ask what happens if they cease trading — some warranties are backed by third parties or insurance.

Comparing proposals

Force every quote onto the same lines:

Confirm what's included: permits and interconnection, any panel or electrical work, monitoring, removal of old equipment, and whether the roof is assessed.

A quote that excludes permitting isn't comparable to one that includes it. See solar permits and interconnection.

What are the red flags in a solar quote?

Pressure to sign today. Any legitimate proposal survives a week of consideration. Urgency is a sales technique.

No site visit before a firm quote.

A production estimate with no stated assumptions — no derate, no shading analysis, no monthly breakdown.

Vague warranty terms, or reluctance to put them in writing.

Refusal to itemize the quote.

Claims about savings or incentives that aren't in writing with a source. Programs change; verify current eligibility yourself with the utility or program rather than relying on a salesperson's summary.

Door-to-door with a same-day discount.

Discouraging you from getting other quotes.

No mention of your electrical panel on a project that connects to it.

Financing: separate the decisions

If financing is offered, evaluate the system and the financing independently.

A good system on poor financing terms is a poor deal. Compare any offered financing against what you could obtain independently, and read the terms — particularly on leases and power purchase agreements, where you don't own the system and the obligations run for a long time.

See solar loan vs lease vs PPA.

Questions worth asking

1. How many installations have you completed locally, and over how long?
2. Will you visit before quoting?
3. What derate does your production estimate apply, and what shading analysis did you run?
4. How do you flash roof penetrations? (Their fluency here tells you a lot.)
5. How long is the workmanship warranty and does it cover roof leaks?
6. Does it cover labor for warranty replacements?
7. What's the realistic timeline here including permission to operate?
8. Is any electrical panel work needed, and is it in the price?
9. What happens if production falls short of the estimate?
10. Can I speak to customers from three or more years ago?

That last one is more useful than recent references — it tests whether they're still responsive after the sale.

The bottom line

Verify licensing and insurance, insist on a site visit, and judge the production estimate on whether it states its derate and models your actual shading — that's the clearest signal of engineering rigor. Compare proposals on estimated annual production per total dollar, weigh the workmanship warranty heavily (especially roof leak coverage), and treat company longevity as part of that warranty's value. Walk away from urgency.

Model economics with the solar panel payback calculator, sanity-check estimates with the solar output calculator, or read the solar installation process.