When a solar installer is sitting across from you, the right questions are your best tool for telling a good operator from a dodgy one — and you don’t need to be technical to ask them. A capable, honest installer will answer all of these clearly and without defensiveness; a poor one will dodge, bluster, or oversell. Here’s the checklist to take into every quote, grouped by what each question reveals.
Certification and legitimacy
These confirm the work will be legal and safe — the non-negotiables:
- “Who does the electrical work, and are they a registered electrician?” The connection is prescribed electrical work; it must be a registered electrician.
- “Will I get a Certificate of Compliance?” The answer must be yes — it’s your legal proof the work is safe and to standard. No CoC, no deal.
- “Is the install to AS/NZS 5033 and 4777, and is there an independent inspection for the grid connection?” A good installer knows these and says yes without hesitation.
- “Are you accredited with a recognised industry body?” This is also what banks require for green-loan finance.
Equipment
These reveal what you’re actually getting:
- “What panel brand, and what are the product and performance warranties?” Look for a reputable brand and clear, separate warranty terms.
- “What inverter — type, brand, and warranty?” Don’t let the inverter be glossed over; it’s the part most likely to be replaced.
- “Is it battery-ready if I want storage later?” Relevant if a battery is even a maybe.
Sizing and savings
These test whether they’re being honest or just selling:
- “How did you size this system, and why this size?” You want it matched to your usage, not the biggest they can sell.
- “How did you calculate the savings, and can I see the assumptions?” Expect a range with reasoning — be wary of one big, round number or a suspiciously short payback.
- “What self-consumption did you assume?” A telling question — good installers base savings on how much of your own power you’ll use.
The quote and what’s included
These surface hidden costs and corner-cutting:
- “Is the quote itemised — panels, inverter, mounting, labour, extras?” Itemised quotes are easier to trust and compare.
- “Does it include scaffolding, any switchboard upgrade, and the grid-connection paperwork?” These are the common “surprises”; confirm they’re in, not extra.
- “What’s your workmanship warranty?” This covers the installation itself — the most likely source of real-world problems.
The company
This checks they’ll be around to stand behind the work:
- “How long have you been operating, and can I have references or recent installs nearby?” Longevity and references matter for warranties that may need claiming years from now.
How to use the answers
You’re listening for two things: clear, confident, specific answers (a good sign) and a willingness to put it in writing. Vagueness, pressure to sign quickly, or irritation at being questioned are all warning signs. Ask the same questions of two or three installers and compare — the way they handle scrutiny tells you a lot about how they’ll handle your roof.
The verdict
The right questions separate good installers from bad without any technical knowledge on your part: confirm the registered electrician, the Certificate of Compliance, the standards, and accreditation; pin down the panel and inverter brands and their warranties; test how they sized the system and calculated savings; check the quote is itemised with nothing important left out; and confirm a workmanship warranty and a company that’ll last. Clear answers in writing are a green light; evasion or pressure is your cue to walk. (See also how to choose an installer.)
Get a free assessment for an independent baseline before you start interviewing installers.
Sources: Installer vetting, certification, and standards per EWRB, Standards NZ, and NZ industry guidance (2026).