Judge the survey, not the brochure
A serious company measures before it quotes: roof area and orientation, shading through the day, distance from array to inverter, existing distribution board condition, and twelve months of consumption.
A company that quotes a kW figure over the phone without any of that is selling a number, not a system. The design work it skipped will show up as underperformance later.
The verification checklist
Run every shortlisted company through these checks before you compare price.
- Named panel and inverter models on the quotation, not just brand categories.
- Reference sites you can actually visit or call, ideally of similar size to yours.
- In-house installation team rather than an unnamed subcontracted crew.
- Written scope covering net-metering documentation and who handles the utility process.
- A defined after-sales process: response window, visit basis and who to contact.
- Structure specification stated in the quotation, including material and treatment.
Warranty language that matters
Manufacturer warranties on panels and inverters come from the manufacturer, not the installer. What the installer owes you is workmanship: mounting, cabling, terminations, earthing and weatherproofing.
Ask specifically what the installer covers, for how long, and how a claim is raised. A verbal assurance is not a warranty, and an unwritten one costs nothing to give.
Questions that expose weak installers
Ask these four in the first meeting and listen for specifics rather than reassurance.
- What DC cable size are you using, and why that size for this run length?
- What surge and earthing protection is included, and where is it installed?
- What happens if generation drops 20 percent in year two — what is your process?
- Who files the net-metering application, and what is excluded from your scope?
Frequently asked questions
- Should I choose the cheapest quotation?
- Only after normalising the scope. Cheap quotations usually exclude protection hardware, net-metering work, or use a lower inverter class, so the final delivered cost is often higher.
- Does company size matter?
- Continuity matters more than size. What you need is a team that still answers the phone in year four and has a documented after-sales process.
- How many quotations should I collect?
- Three is enough if you force them into the same comparison table. More than that usually adds noise rather than information.