If you are building a new house and are thinking about a solar system (or a battery) later, the best advice I can give you is: get your solar installer involved before the plasterboard is installed.
I know it’s tempting to wait until construction is complete to use the solar system, but until then you’ve missed the best opportunity to properly route the wiring and hide it neatly in the walls.
If your contractor wants to “help out” by hiring their own Sparkie to run the solar cables during framing, that can work—but only if it’s done right.
And that means:
- Your solar installer must inspect or approve the cable routing before it can be completely covered.
- There should be photos of everything – the conduit, the cable markings, the grounding – and perhaps even some test results to prove compliance.
Otherwise, you run the risk of ending up in a situation where your plumber either can’t sign off on the job or has to run new pipes through your beautiful new facade. Trust me – I’ve experienced it more times than I’d like. A little early planning can save you headaches later.
The words no solar installer should hear
For solar installers visiting a new home, there often comes a moment when the builder says, “Don’t worry, our electrician has already installed the solar cables for you.” Yes… this is the time to worry.
On the surface, it sounds like a time saver. But in reality, it could be the start of a very expensive and very frustrating game of “guess what’s behind the cast.”
The warning signal: If your installer has not carried out the shell construction
If your solar installer is responsible for installing and certifying the system rather than laying the cables, they will do much more than just make the final connections. They assume liability for work that they have not seen, cannot check and which they have not inspected.
In an ideal world, the same team that does the rough work would also complete the installation. This way they know exactly what is in the walls, what wiring was used and what type of cable was installed. But we don’t always live in an ideal world – we live in a world full of construction deadlines and a “she’ll be right” attitude.
There is no compliance shortcut
This is not just a hypothetical scenario, but something that has actually been reported to me as a solar inspector.
Installers tell us they are losing jobs to competitors who are happy to accept pre-wiring from a contractor and a certificate from the developer. In Victoria this could be a Non-Mandatory Certificate of Electrical Safety (COES). In NSW it is a CCEW (Compliance Certificate of Electrical Work). Every state has its version.
But here’s the problem: These certificates don’t certify that the work meets solar compliance standards. A non-prescribed COES does not cover required electrical work – and solar systems absolutely fall into that category.
So let’s call this practice what it is: risky and non-compliant. Just because someone gave you a certificate doesn’t mean that the work behind the walls is proper or even legal. And if you’re a plumber who takes the hit for doing everything by the book, you’re not alone – and you’re not wrong. This needs to be addressed and it needs to stop.
What really lies behind the walls?
Let’s say the contractor roughened up the DC wires. Your installer didn’t see it. The plaster is up. Maybe they have a blurry photo from three weeks ago taken with 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 in that wall? Without photos taken during shell construction, it cannot be confirmed whether the correct conduit was used or whether the DC wiring is standard. However, the installer is still expected to take full responsibility. This is exactly why your solar installer needs to be involved early – before the walls are sealed and the guesswork begins.
What could go wrong?
- Wrong type of cable (PV1-F and even AC rated stuff seen more times than I’d like to admit)
- No line – or the wrong line (not HD, torn or already crushed)
- Cable not secured securely
- No ground conductor
- Installed directly on the plasterboard, without mechanical protection
Now for mechanical protection…
If a DC cable is installed less than 50mm from a building surface, it must be protected so that it can move freely – or, more importantly, so that it does not become nailed or screwed in later. This isn’t just a solar thing. This requirement actually comes straight from AS/NZS 3000. Yes, the good old wiring rules.
Now specialist installers know that AS/NZS 5033 is the bible for solar installations – and they need to know it thoroughly. But a general electrician, especially one not involved in solar energy, may not realize that the mechanical protection rules of AS3000 still apply to DC cables within cavity walls.
And an HD cable channel may not be enough. In some cases you will need a steel pipe or something that meets the mechanical protection class WSX3. Most of the time, the contractor’s electrician doesn’t even know what that means – and honestly, I don’t blame him. It’s not their world.
What I would expect (as an inspector)
If installers absolutely need to take on a job where the pre-wiring has been done by someone else, they should ask about the following before approval:
Clear close-ups of:
- Line type (confirm it is HD or better)
- Cable markings show it is DC compliant (meets IEC standards)
- Ground conductor (correct diameter and securely installed)
- Cables attached correctly – no loose spaghetti
- Leave both ends loose so you can check what was done
Test photos show:
- Continuity of DC conductors
- Continuity of the Earths
- Insulation resistance test results
- No photo, no proof, no installation.
Who bears the risk?
Here’s the fun part. If the installation is thrown back by the inspector – or worse, fails – your installer is in trouble. Not the builder. Not her Sparkie.
Solar installers bear the risk. And unfortunately, builders often push this risk downwards – directly onto the subcontractors. Why? Because they can. And because their margins come first.
So when installers are asked to approve someone else’s hidden wiring work, remember: it’s their license at stake.
What installers should tell builders
I understand it. It’s awkward. Builders don’t want to hear “no.” They want the work done yesterday, and they want you to “just work with what’s there.” But here you need to put your feet up and calmly say:
“Mate, if I can’t check what’s in that wall, I can’t sign it. I’m not risking my license for something I didn’t see.”
They might not like it. But they will respect it – eventually. And if not? Well, maybe they weren’t the type of contractor you wanted to work with anyway.
Final word: protect yourself
Pre-wiring in a new build can work – if done correctly, properly documented and checked before the plasterboard is installed. However, if your installer hasn’t done the work and can’t prove how it was done, they’re being asked to take a hit-or-miss approach.
And I don’t know about you, but I don’t care about signing mysterious cables to someone’s $900,000 house.
Speak louder. Ask for proof. And if it doesn’t work, walk away. Your home is worth more than a builder’s shortcut.
For more information about buying solar energy, check out SolarQuotes’ detailed guide to what you should know.
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