'Huge bang' prompts maintenance inspection advice for old solar panels

Rooftop fires caused by solar panel equipment have prompted industry groups to call for increased maintenance checks with fears the issue is a tragedy waiting to happen.

Home owner Anthony Parisi said he panicked when he heard an explosion on his roof last year, unsure if something had fallen from the sky.

"We were just at home and heard this huge bang," he said.

"[We] didn't really know what it was at the time. It just sounded like something had fallen onto the roof or run into the roof."

When Mr Parisi investigated he found a box connected to his solar panels had exploded.

"The box was just broken and had come apart," he said.

"There were pieces of aluminium near it, some of it had twisted back from the explosion."

The aluminium box contains the solar panel isolator — a safety device that can be used to manually disconnect power to the solar panels.

Solar power business owner Mark Cavanagh said the isolator was set up to disconnect the direct current power that feeds to the inverter.

"It's designed for firefighters in case there's a fire and they want to turn off that power that is going through your roof," Mr Cavanagh said.

According to Queensland Fire and Emergency Services Acting Superintendent, Mark Burchard, the majority of fires involving solar panels are caused by isolators.

"Very minimal fires [are caused by] the solar panels or the inverters. That's not to say that doesn't happen but [the] majority are with the isolator," he said.

There are a number of reasons why the isolators are catching alight, including exposure to the elements.

When first introduced, enclosure boxes, which protected the switches from the elements were not mandatory, causing them to ignite after being exposed to the sun.

About the same time, multi-hold glands were introduced, which made the isolators watertight.

But Mr Cavanagh said that was not as effective as hoped.

"Condensation would still get into it, and that water couldn't get back out," he said.

"So, there was a period [about four to six years ago] where we've had issues with them.

"Condensation gets in, and [that] builds up, and that just shorts out the connection over time."

Breather valves were then introduced in 2018 to ventilate the switches.

But isolator models which fell within the period before breather valves were introduced have continued to cause the majority of solar panel blazes.

"You can have a small fire contained to the isolator, depending on where it is, you can lose a house," Acting Superintendent Burchard said.

Data from the Queensland Fire and Emergency Services shows there were 60 fires relating to solar panels last year — 37 of those were believed to have been caused by isolators.

For nearly a decade from 2012, Australia was the only country which mandated rooftop DC isolators.

But in 2021, the Australian solar installation standard was updated to remove the requirement, if all other safety measures were followed.

Peak body for solar power, the Clean Energy Council requires systems older than May of 2022 to have rooftop isolators.

"If your system is older than mid-2018 and has not received maintenance, then we would strongly urge you to get a maintenance inspection done on your system."

While regular maintenance is recommended, it's not required under state and territory electrical safety laws.

But electricians maintain getting isolators checked could save a lot of heartache.

"It's a real quick fix if you have any issues ... you are putting a power station on your roof. You want to make sure you do it properly," Mr Cavanagh said.

Mr Parisi said despite the fright of the explosion on his roof, he doesn't regret getting solar panels.

"Our bill went from something like $1,500 to $1,700 a quarter down to about $200 to $300 a quarter.

"It made a significant difference to our costs."