Solar Power System Fires And Blasted Rooftop Isolator Switches

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.”
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.
Fire and Rescue NSW stated last year solar panel related fires had increased five-fold in the previous five years, but didnt 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.
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 wasnâ????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.
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.
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.
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 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).
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.
ADELS NL1 Series DC Isolator Switches are applied to 1-20KW residential or commercial photovoltaic system, placed between photovoltage modules and inverters. Arcing time is less than 8ms, that keeps solar system more safe. To ensure its stability and long service life, our products are made by components with optimum quality. Max voltage is up to 1200VDC. It holds a safe lead among similar products.