The Unseen Craftsmanship of A Good Solar Install: Array Cabling

residential solar panels in Australia

Did you know that a staggering 90% of solar installation defects are found on the roof?

Under the solar panels is where seasoned professionals distinguish themselves, installing systems with a priority on longevity and safety. The hidden solar panel array cabling, often overlooked, speaks volumes about the installer’s dedication—or lack thereof.

As a Licensed Electrical Inspector (LEI) I’ve learned that array cabling is the #1 predictor of an installation’s fate. By checking the array cabling, I can usually quickly tell whether I’m gonna to be inspecting a piece of craftsmanship or whether I will be onsite for the following 2 hours writing up defects.

With my Dunlop Volleys on the tiles and my zoomed in iPhone on the details, I ensure that the solar systems I inspect are safe, sound, and precisely installed. Because when it comes to solar, the true test of craftsmanship is not just what you can see from quick drone shot, but what holds up against the stormy weathers of time.

Here are 5 examples of array cabling which I see day to day. There are usually clues here as to the standard of the workmanship throughout the installation. Some key DOs & DON’Ts. You may notice that the problem images have multiple defects, this is typical of what I see out there.

#1: Running Array Cabling Behind Frame Nuts in Rail Channel

I observe this troubling shortcut way too frequently: installers running array cabling behind the frame nuts in the rail channel.

It’s a gamble that places undue stress on cables due to thermal expansion and risks damage from unaware future technicians.

It is also likely to damage the conductor’s insulation during installation as the insulation is stripped back on the edge of the array fixing nuts.

My advice? Steer clear of the rail channel. Secure cables externally with robust fixings like panel clips or cable ties.

rail and dc cable

Bad: Cable installed inside rail channel, damaged insulation during installation

dc cables in rail

Bad: Multiple cables run inside rail channel. It’s easy to see how this could become an issue down the track with expansion & contraction due to weather conditions or if someone turns the bolt in the vicinity.

cables external to rail

Good: Cables installed external to the rail channel – good job.

#2: Running Cables on Catenary Wire

Using a catenary wire to fix array cabling conductors to can be a handy way to place cables where you want to when there is nothing else to fix them to. I have noticed it recently becoming quite popular.

I’ve crossed paths with installations where array cabling entwines catenary wire like ivy, lacking any formal anchorage. The completed wiring loom somewhat resembles spiral pasta. This practice raises red flags.

Dodgy installers defend it, expert installers just don’t go there. It’s not just about meeting the bare minimum of AS3000. It’s crucial for installers to ensure their catenary wires adhere to the latest standards, which, according to AS/NZS 5033:2021, mandate earthing unless the wires are insulated or do not make contact with DC conductors.

The best practice? Use cable ties to secure the conductors to the earthed catenary wire, creating a visually tidy and stable setup that leaves no room for doubt or debate.

spiral earth on catenary

Bad: Cables wrapped around the catenary wire in a spiral like manner, not securely fixed in position

catenary earth wire

Good: Catenary wire done right – nice work

#3: Pulling Cables from the Panels Tight and Under Strain

In solar installations, tension on conductors & connections is the enemy. As an LEI, I’ve witnessed the strain that overly taut cables exert on solar panel connections, risking damage to the delicate junction boxes and potentially voiding manufacturer’s warranties.

It’s a fine art, ensuring that each conductor from the modules is laid out with the requisite slack and supported just so, to ward off any strain and paying attention to the cable’s minimum bending radii. This is especially crucial at disconnection points and at the ends of rows—precision here is non-negotiable.

Installers who use unskilled or unlicensed labour for all their roof work may come unstuck here as this requires skill, expertise and cannot be successfully performed by a trained monkey.

tight dc cabling under solar panel

Bad: Cables to modules pulled tight and under strain, likely to fail over time

dc cable from solar panel with strain relief

Good: Cables from modules with a nice sweeping bend – great stuff

#4: Reliance of PVC Cable Ties

Navigating the unforgiving Australian sun, it’s clear that the common PVC cable ties are a false economy. They may initially save some cash, but under the relentless sun, they’re destined to fail, risking your entire solar system. I’ve also heard stories of broken PVC cable ties falling into gutters and blocking drains with disastrous consequences.

In my professional view, selecting stainless steel cable ties or sturdy clips is a smart move, offering durability against the brutal UV assault and temperature fluctuations. While PVC ties may be utilised to tidy up appearances, they shouldn’t ever bear the weight of securing your array conductors as the primary means.

And a word to the wise: when tightening steel ties, a gentle hand is key to avoiding insulation damage and potential earth faults – good installers already know this.

pvc cable tie and dc solar cable

Bad: One PVC cable tie holding up the return cable, what happens when the tie becomes brittle and gives way?

pvc and stainless cable ties

Good: PVC cable ties being used as a secondary means of fixing to tidy up – they are still useful when used right

#5: Not Enough Fixing Points Causing Sagging and Unnecessary Movement in Windy Conditions

It’s still too common to see not enough fixing points holding the array cabling in position. When array cables sag a bit, it’s poor workmanship and may lead to unnecessary wear & tear on the conductors. When cables are in touching the roof surface, it can quickly become dangerous.

It’s worth noting that many years ago I saw an array conductor & MC4 connector which was never attached to the array and laying on a tin roof. I found the MC4 burnt out and the conductor now exposed and in contact with the roof surface. The roof sheets were live and I found myself having to deal with an unsafe installation.

Nesting of wildlife is not uncommon under arrays. This is not an ideal situation, although can cause further complications and harm when unsecured array conductors are involved.

My advice, spend a few extra moments and a few extra fixings securing conductors. Less hassle later, much safer now and it will look great. A small step which will pay off in the long run.

sagging dc cable

Bad: Return cable sagging, image what it would be doing in strong winds.

good dc cabling

Good: Lovely array cabling – all secure & safe

Conclusion

It’s important to recognise that good array cabling is like the unsung hero of solar installs – it’s all about the details. It saves you from a heap of trouble down the road and keeps everything safe and reliable.

So, here’s to doing it right – slap on those clips, secure those cables, and let’s make sure our solar setups stay strong for the long haul, without any hiccups. Because who wants to climb back up on the roof and fix your stuff ups?

About Pat Southwell

Pat Southwell is a Licenced Electrical Inspector, solar installer and electrician based in metropolitan Melbourne who also travels all over regional Victoria. With experience as a Solar Victoria auditor, CER Inspector, and a background at the Clean Energy Council (CEC), Pat is well-known in the industry. He's a devoted family man, with five children, who enjoys playing park cricket in the summer.

Comments

  1. Richard Courtenay says

    I put all my cables in flexible conduit as per normal electrical standards. this way I avoid damage by mechanical or animal causes. It takes more time and money but is good insurance. you can tie conduit to catenary wire as per normal 240 volt practice. parrots and vermin love to chew at cables.

  2. I had a solar system throw up earthing errors after rain/damp and found out (by myself, as the company went out of business) that the connectors were not tucked away, safe from moisture.

    Water/sediment/gunk had built up on them and would hold moisture for a few hours to a few days, triggering errors on the inverter.

    It was an easy fix, and one to look out for.

    • Is electrical inspection of solar panel installation a requirement? I had panels & an inverter installed about 4 or 5 years ago and don’t ever recall any inspection of these?

  3. A couple of points here to think about.

    Cable ties – always use UV stabilised cable ties. They will be affected by the sun and will last as long as the panels. Also use a proper cable tie tool that tensions them correctly and cuts the end flush. As an aircraft engineer I see cable ties that are exposed to all sorts of poor conditions in engine bays, undercarriage wells….. all suffering extreme exposure to all kinds of fluids, heat, and cold, no problems at all.

    Cable runs – again, in aviation we run long wiring looms all the time. Again as above exposed to all sorts of elements. The trick is to add “expansion” loops or turns every couple of meters. We do the same with fluid carrying hoses or pipes. Never straight point to point.

    To me this is a training issue with installers not being trained in the correct materials and cabling techniques.

    I have worked on 40 year old aircraft and the cable ties and looms are all good.

  4. Erik Christiansen says

    Typo?: “maximum bending radii” -> “minimum bending radii” perhaps.

  5. I’m struggling to get my installer to replace a panel that is yielding 60% of what the panels surrounding it yield. Asking them to fix poorly fixed cabling would be wishful thinking.

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