Don’t Make This Solar Mistake In A New Home Build

If you’re building a new home and thinking about solar (or a battery) down the track, the best advice I can give you is this: get your solar installer involved before the plasterboard goes up.

I know it’s tempting to leave solar until after the build’s done, but by then, you’ve missed the best opportunity to get the wiring right and hidden neatly inside the walls.

If your builder wants to “help out” by getting their own sparkie to run the solar cables during framing, that can work — but only if it’s done properly.

And that means:

• Your solar installer needs to review or approve the cable run before it’s all covered up.
• There should be photos of everything — the conduit, the cable markings, the earthing — and maybe even some test results to prove it’s compliant.

Without that, you risk ending up in a situation where your installer either can’t sign off on the job, or has to run fresh conduit down your beautiful new facade. Trust me — I’ve seen it happen more times than I’d like. A bit of planning early on can save you a headache later.

The Words No Solar Installer Should Want To Hear

There often comes a moment for solar installers visiting a new home when the builder says: “Don’t worry, our electrician’s already run the solar cables for you”. Yeah… that’s the moment to start worrying.

On the surface, it sounds like a time-saver. But in reality, it could be the beginning of a very expensive, very frustrating game of “Guess What’s Behind the Plaster.”

The Red Flag: When Your Installer Didn’t Do the Rough-In

If your solar installer didn’t run the cables, but is expected to fit off and certify the system, then they’re taking on a lot more than just the final connections. They’re taking on liability for work they didn’t see, can’t verify, and didn’t control.

In an ideal world, the same crew that does the rough-in would also finish the install. That way, they know exactly what’s in the walls, what conduit was used, and what kind of cable was run. But we don’t always live in an ideal world — we live in a world of builder deadlines and “she’ll be right” attitudes.

There’s No Such Thing As A Compliance Shortcut

This isn’t just a hypothetical scenario — it’s something that’s actually been reported to me as a solar inspector.

Installers are telling us they’re losing jobs to competitors who are happy to accept a builder’s pre-wiring and a certificate from the builder’s sparkie. In Victoria, that might be a non-prescribed Certificate of Electrical Safety (COES). In NSW, it’s a CCEW (Compliance Certificate of Electrical Work). Every state has its version.

But here’s the rub: these certificates don’t verify that the work meets solar compliance standards. A non-prescribed COES does not cover prescribed electrical work — and solar installs absolutely fall into that category.

So let’s call this practice what it is: risky, and non-compliant. Just because someone has handed you a certificate doesn’t mean the work behind the walls is up to scratch — or even legal. And if you’re an installer who’s taking the hit because you’re doing things by the book, you’re not alone — and you’re not wrong. This needs to be called out, and it needs to stop.

What’s Really Hiding Behind the Walls?

Let’s say the builder’s sparkie has roughed in the DC cables. Your installer didn’t see it happen. The plaster’s up. Maybe they got a blurry photo from three weeks ago, taken on a first-generation Nokia camera phone that looks like it’s been through the wash.

Looks neat now, but the real question is — what’s going on inside that wall? Without photos taken during the rough-in, there’s no way to confirm if the correct conduit was used or if the DC cabling meets the standard. And yet, the installer’s still expected to take full responsibility. This is exactly why your solar installer needs to be involved early — before the walls are sealed up and the guesswork begins.

What could go wrong?

• Wrong cable type (seen PV1-F, and even AC-rated stuff more times than I care to admit)
• No conduit — or the wrong conduit (not HD, cracked, or already crushed)
• Cables not fixed securely
• No earthing conductor
• Installed right up against plasterboard with zero mechanical protection

Now, about that mechanical protection…

If a DC cable is installed within 50mm of a building surface, it needs to be protected so that it can move freely — or more importantly, so it doesn’t get nailed or screwed into later. That’s not just a solar thing. That requirement actually comes straight out of AS/NZS 3000. Yep, the good old Wiring Rules.

Now, specialist installers know that AS/NZS 5033 is the bible for solar installs — and they need to know it back to front. But a general electrician, especially one who doesn’t do solar, may not realise that the mechanical protection rules from AS3000 still apply to DC cabling inside internal cavity walls.

And HD conduit might not cut it. In some cases, you’ll need steel conduit or something that meets a WSX3 mechanical protection rating. Most of the time, the builder’s electrician won’t even know what that means — and honestly, I don’t blame them. It’s not their world.

What I’d Expect to See (As an Inspector)

If installers absolutely have to take on a job where the pre-wire was done by someone else, here’s what to ask for before signing off:

Clear, close-up photos of:

• Conduit type (confirm it’s HD or better)
• Cable markings showing it’s DC-compliant (meets IEC standards)
• Earthing conductors (correct gauge and securely installed)
• Cables secured properly — no loose spaghetti
• Slack at both ends so you can verify what’s been run

Testing photos showing:

• Continuity of DC conductors
• Continuity of earths
• Insulation resistance test results
• No photo, no proof, no install.

Who Cops the Risk?

Here’s the fun part. If the install gets knocked back by the inspector — or worse, fails down the track — your installer is on the hook. Not the builder. Not their sparkie.

Solar installers wear the risk. And unfortunately, builders often push that risk downhill — straight onto the subcontractors. Why? Because they can. And because their margins come first.

So when installers are being asked to sign off on someone else’s hidden cabling work, remember: it’s their licence on the line.

What Installers Should Be Saying to Builders

I get it. It’s awkward. Builders don’t want to hear “no.” They want the job done yesterday, and they want you to “just work with what’s there.” But this is where you need to plant your feet and calmly say:

“Mate, unless I can verify what’s in that wall, I can’t sign it off. I’m not risking my licence for something I didn’t see.”

They might not like it. But they’ll respect it — eventually. And if they don’t? Well, maybe they weren’t the kind of builder you wanted to work with anyway.

Final Word: Protect Yourself

Pre-wiring during a new build can work — if it’s done right, documented properly, and verified before the plasterboard goes up. But if your installer didn’t do the work, and can’t prove how it was done, they’re being asked to sign off on a lucky dip.

And I don’t know about you, but I’m not in the business of signing off mystery cables inside someone’s $900,000 home.

Speak up. Ask for proof. And if it doesn’t stack up, walk away. Your home is worth more than a builder’s shortcut.

For more on buying solar, read SolarQuotes detailed guide on what you should know.