Trouble with unsafe DC isolators


Image: Safer Solar

Fires caused by unsafe solar mandates

Rooftop DC isolators have come under fire lately due to safety and regulatory concerns. In an interview with pv magazine, head of Queensland-based renewables company REA Global , Michael Mrowka has stated that,

“One example is the AS/NZS 5033 standard that mandates rooftop solar isolators, which have become the largest single cause of solar fires in recent years,” he said. “Combine that with low-cost Chinese products that can be quite dangerous as they age, especially when poorly installed, and you have a ticking time-bomb that can cause electrical shorts and fires.”

Standards Australia launched a review of AS/NZS 5033 last month. More than 680 submissions have been received from the public during the comment period, which ended last month.

“The safety issue is very difficult because governments have given out so many rebates for what may be potential fire hazards that this could be another pink batts installation debacle,” he said, referring to a government-funded insulation scheme that was abandoned in 2010, following the death of four workers and a string of house fires.

The PV market has been experiencing steady growth and the industry is now poised to eclipse its previous global sales record. That said, that increase in demand has also had some unintended side effects, with Fire and Rescue NSW data showing a five-fold rise in PV-related fires over the past five years.

The safety mechanism of DC isolators were originally intended to manually disconnect solar panels for maintenance, installation and repair purposes, by disabling dangerous high-voltage DC between the solar array and inverter. However, DC isolators can easily degrade and malfunction and they have been blamed for causing almost half of solar panel fires. They have done more harm than good.

The alternative says, Mr. Mrowka is ‘If we could change one thing to improve this situation, it would be to mandate rapid shutdown and panel-level monitoring and communication.’

The Clean Energy Council (CEC) are among those advocating an amendment to this rule. A CER report has identified that water ingress is the biggest safety risk associated with rooftop PV. The CEC has recommended isolating the DC circuit near the inverter, instead of as a separate switch near the inverter as the best solution.

DC Isolators required for now

Generally installers feel pretty strongly about rooftop DC isolator switches. They’ve been campaigning to have them removed from the AS/NZS 5033 Standard for years but it can be hard to make any swift changes. While AS/NZS 5033 also applies in New Zealand, NZ installations do not require rooftop isolators.

Last year, members from the Clean Energy Council gave their in-principle support to do away with wall mounted DC isolators, and for DC isolators to be enclosed within the solar inverter.

We highly recommend for solar panel owners to undergo inspection and system tests, performed every five years by qualified installers, to ensure professional maintenance is kept up and that your solar pv system is operating safely.

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