DC isolators trigger sharp increase in solar fires in Australia

Data shows a sharp increase in the number of fires caused by the DC isolators that separate the grid from solar panels. ABC News gathered state-by-state data revealing a dramatic increase in fire incidents in the last 12 months.

September 19, 2023 Carrie Hampel

Image: Safer Solar

From pv magazine Australia

Fire incidents caused by DC inverters in rooftop solar installations have increased sharply over the last 12 months in Australia, according to data gathered by the ABC.

In the Northern Territory this year, 11 fires have been caused by DC isolators, compared to just four in 2022. The state of Victoria saw 27 fires caused by isolators in the last financial year, up from 15 the year before. Meanwhile, Queensland had 11 last year, and Western Australia had 14 fire incidents caused by DC isolators. The Australian Capital Territory had at least one incident in the last year, while New South Wales authorities did not respond to requests for data. No data was shown for Tasmania.

Until 2021, Australia mandated DC isolators be part of every system. It was the only country to have such a requirement. After industry experts lobbied against the use of DC isolators, saying they actually made systems more vulnerable to fires and faults, the mandate was finally abandoned in November 2021. Since the requirement for DC isolators was only revoked in practice six months later in mid-2022, most solar installations on Australian rooftops will have DC isolators.

A spokesperson from Energy Safe Victoria told the ABC that a key driver in the increase in fire incidents was a lack of servicing of rooftop solar systems. He said that their research showed that although people with photovoltaic installations on their roofs understand the importance of servicing, they still don’t do it.

While existing laws recommend owners have their PV system inspected regularly and annually for system components like DC isolators, regular inspections are not required under state and territory electrical safety laws.

As pv magazine reported in November 2021, another disadvantage of isolator components is that they can degrade from environmental exposure. This can be due to specific installation methods and product types, increasing the likelihood of water ingress and ultraviolet radiation damage. This was again reflected in the accounts of those experiencing the fires in a report broadcast by the ABC yesterday. In 2021, pv magazine concluded that DC isolators may need to be replaced within the life of the panels of a PV system.

NT Worksafe has now issued a safety warning and advised people to check their solar installations – especially to make sure that DC isolators were not on or near wooden surfaces.

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