Solar Power System Fires And Blasted Rooftop Isolator Switches

Solar rooftop DC isolator switch fire

There have been several fire incidents in New South Wales in the last week or so involving solar power systems – and at least two are thought to have been caused by rooftop isolator switches.

Yesterday, Fire and Rescue New South Wales reported it had attended an incident at a home in Woongarrah on the Central Coast after a triple-zero caller reported smoke issuing from the roof of the home.

“Firefighters from Hamlyn Terrace and Doyalson fire stations arrived on scene a short time later and were able to quickly extinguish the fire and ensure it had not spread further,” said Fire and Rescue. “FRNSW’s Fire Investigation and Research Unit are currently working to establish the cause of the fire, which is believed to have started in the isolation switch.”

The isolator switch involved is pictured above.

On December 30, firefighters and police were called to an address in the Newcastle suburb of Bar Beach after reports a home’s rooftop solar panels were smouldering. Again, the fire was put out before any major structural damage could occur. A potential cause wasn’t mentioned.

On December 28, FRNSW were called to respond to a house fire in Lake Cathie, south of Port Macquarie. The cause noted was a rooftop isolation switch.

Isolation Switches A Common Solar Fire Culprit

Fire and Rescue NSW stated last year solar panel related fires had increased five-fold in the previous five years, but didn’t provide any numbers. More than 600,000 solar power systems have been installed in New South Wales, and wherever widespread electrical appliances are involved there will be incidents – but this shouldn’t just be accepted if there is room for improvement.

And there is.

FRNSW has previously noted isolator switches have accounted for around half of solar power system fires in the state. While the proportion of rooftop isolators being the culprit wasn’t mentioned, its likely a majority of them were given the track record of these problematic devices.

A rooftop DC isolator switch is a manually operated switch installed next to a solar panel array enabling the DC current between the array and the solar inverter to be shut off. Ironically, it was intended as an additional safety mechanism and is a requirement for all solar power systems in Australia. But we seem to be the only country that still requires their use.

Many solar installers despise having to install rooftop DC isolator switches and there are moves to have the requirement removed from Australian Standards – and that can’t come too soon. There’s also a push to do away with wall-mounted isolators; instead requiring an isolator incorporated within the solar inverter.

Those are a couple of improvements that can be made – another is owners having their systems checked.

Good quality DC isolator switches properly installed and effectively protected by a shroud are generally safe. A shroud is another requirement that has been in place for some time and the isolator switch in yesterday’s incident didn’t appear to have one. Perhaps the installation pre-dated the requirement, but the setup generally looked to be a bit dodgy.

Fire safety is another important reason for choosing a good solar installer. But regardless of component and installation quality and given the harsh conditions rooftop DC isolator switches and other components of a solar power system have to endure over many years, it’s important to have an inspection and system test performed every few years.

About Michael Bloch

Michael caught the solar power bug after purchasing components to cobble together a small off-grid PV system in 2008. He's been reporting on Australian and international solar energy news ever since.


  1. Bret Busby in Western Australia says

    The primary objective of Shonkiness Australia, is to make life increasingly dangerous, isn’t it?

    After all, that is why they imposed the stupid requirement to put DC isolators on rooftops, so that they would cause problems, isn’t it?

    It is a bit like requiring hot water systems to breed and spread legionella, by banning hot water from water heaters.

  2. Never really understood that logic of the DC isolator having to be on the roof panels. The average user will not get up a ladder to isolate the panels for any reason. The isolators should be at ground level within easy reach.

    I have 3 solar systems. The first one installed in 2011. No DC isolator on the panel but there is a DC isolator next to the inverter.

    The second system was installed 2013, it has DC isolators on the roof panels.

    The third system was installed in 2018, it has DC isolators on the roof panels as well as being next to the inverter (a double set of DC isolators).

    None have any issues to date.

    Looking at a 4th solar system in the very near future.

  3. what exactly are the shrouds supposed to do?

    • Ronald Brakels says

      The shroud keeps the sun off the DC isolator switch which helps stop it getting too hot and also prevents UV degradation. It also keeps the worst of the rain off it.

  4. Geoff Miell says

    The localities of Woongarrah, Bar Beach, and Lake Cathie, NSW are all apparently proximate to marine environments subject to sea spray.

    Perhaps locations subject to sea spray environments increases the risk of failure and better attention to adequate IP-rated enclosures, switch specs and cable glands/sealing was needed?

    Perhaps solar-PV systems that are exposed to marine environments are more likely to degrade sooner and need inspections more often?

  5. John Corney says

    As a solar designer installer for nine years, I have never been comfortable putting the least reliable part of a solar system into the worst possible environment. I believe the makeup of the panel responsible for inserting that clause in the standard included a representative from the fire department of a particular state who wanted to be able to isolate the system so that he could safely enter the roof space. Why any fireman would want to be on or in a roof space during a fire is unbelievable and utterly stupid. Our friends across the ditch have included a clause in their standard that stating that rooftop Isolators are not required.

  6. Michael Paine says
  7. Timothy O'Leary says

    In todays Conversation…

    Solar panel fire season is all year round and it’s getting more intense in Australia
    Timothy O’Leary, University of Melbourne and David Michael Whaley, University of South Australia


  8. Rod Cunningham says

    We recently noted one of our solar arrays was not working. Our system has been operating for 3 months since installation. A visit from the system installer found the roof top isolator cracked and distorted with the conduit fittings falling from the switch casing. It had overheated with the switch mechanism partially melted. Fortunately it had not caught fire. Our son, a firefighter in the Adelaide metropolitan area has attended 3 rooftop solar fires in the last 3 months and all appear to have been caused by faulty isolators. As a country firefighter I have attended several structure fires. The ability to disconnect the rooftop solar array from the inverter and wiring in the ceiling space to isolate the panels and prevent further damage or electroction is helpful. Otherwise it is a matter of covering the panels with drop sheets, a decidedly risky task on a 45 degree pitch roof.

  9. Although MC4 connectors are not supposed to be separated under load would it not be better to label the one handling the ‘home run’ and have it pulled apart to isolate the string? It could even be that fire fighters use insulated cutters to cut the home run.

    I have isolators, shielded but in a coastal environment, and it does worry me.

  10. Tony Fisher says

    Beware of Offshore Based Inverter Monitoring Systems.
    Many PV System owners with overseas manufactured inverters are not aware that some of the “free” monitoring systems are also running “overseas”, with the PV Array/Inverter production data (and any personal details you may have unwittingly added to your “system description”), being exported from Australia without the owner’s knowledge. (Rule number one in freeware, – “there is always a catch, and nothing is actually for free”).
    After some dialogue with the Australian office for my inverters, – they reluctantly confirmed that my data was being exported to, stored and processed in China, from where the monitoring app was also running.
    That was the point that I decided to disconnect my WiFi connected monitoring, as I was very concerned that I had unwittingly compromised the security of my home network by clicking on the obligatory “I accept” Button, – as required before the software would download to enable the free Inverter monitoring. The manufacturer initially tried to convince me that the app was running on my PC, and the data was also being stored in my PC, but that falsehood was easy to disprove, which then led to the admission that my data was being exported to and stored in China, and the monitoring app was also running in China.
    By clicking the “I accept” button, – I had allowed the Chinese server to establish a VPN through my home network firewall, a situation that I was not at all comfortable with.
    I am now researching a replacement monitoring system, but looking for a holistic monitoring system that can provide meaningful data on usage as well as production, across a number of collocated PV systems, and specifically one that does not export data outside of Australia.
    Appreciate feedback from anyone who may have already solved this problem.

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