Following recent severe flooding along the Australian east coast, Safer Solar is calling for the mandate of a rapid shutdown of photovoltaic systems during disaster events, writes Gavin Dennett.

In March 2022, Australians watched in horror as catastrophic flooding of the Australian east coast devastated towns such as Lismore in northern NSW (pictured above). For people experiencing the natural disaster and the loss of homes, businesses, farms, livestock, livelihoods, and, sadly, human life, the pain and suffering was, and still is, unimaginable.

Among the decimation of property, images of flood-ravaged towns showed rooftop photovoltaic (PV) solar systems destroyed along with the homes they sat atop. While the focus was understandably on saving lives during the rising floodwaters, and not on damaged PV systems and other infrastructure, there was concern these rooftop panels had the potential to wreak havoc in their damaged state.

In one case, a family in northern NSW tied tent ropes to their rooftop solar panels while awaiting rescue from the floods. However, if the sun had come out while they were on the roof, they faced the risk of a damaged solar panel or inverter causing a live electrical current to run through their roof.

According to Australian group Safer Solar – an Australian initiative that aims to raise awareness about AC and DC optimised safe solar technologies available to the Australian market – this example and others during the recent floods highlights the need for Australia to mandate rapid shutdown technology on solar PV systems.

Solar panels are installed on the rooftops on one in four Australian homes, however many systems lack a quick and easy way to shut down in the event of a fault or emergency, which poses a serious safety threat for residents, first responders and tradespeople.

PV panels that were not shut off before the recent floods hit could have potentially begun generating electricity when the sun broke through the clouds without safety systems designed to protect people from uncontrolled high-voltage electrical currents.

More than 90 per cent of rooftop solar PV systems installed in Australia include high-voltage direct current (DC) wiring that is live whenever the sun is shining. This 600-to-1000-volt current – which cannot be shut off during daylight – can jump a 100mm gap between a system component and any earthed conductive material.

Any break in wiring insulation or weather sealing of components can allow an electrical arc to form. Approaching 1000 degrees Celsius, this arc is hot enough to ignite fires. It can also deliver a lethal electric shock.

Safer Solar believes mandates need to be introduced for solar energy management systems that can quickly and easily shut down in the event of fire, flood or other disasters; isolate individual solar panels that fail to meet safety standards through remote management; and remotely monitor solar panels for problems.

Enphase Energy Australia general manager, Australia and New Zealand, Wilf Johnston. Photo: Supplied.

Enphase Energy Australia is a Safer Solar member and it estimates that approximately 700,000 houses equipped with solar panels were in areas hit by the recent east coast flooding. The company’s general manager in Australia and New Zealand, Wilf Johnston, says Australia is lagging behind many other countries when it comes to mandating rapid shutdown of solar systems.

“Rapid shutdown is already mandated in the US so solar panels can stop producing energy in the event of a disaster such as fire, flood or tornado,” he says.

“Even developing countries such as Thailand and the Philippines now mandate rapid shutdown systems. The risk in Australia is increased by the fact that many solar systems are now 10 or more years old, adding a decade’s wear and tear to outdated technology.

“Australia needs to mandate that replacements for these old systems and all new systems meet the highest safety standards, which includes rapid shutdown.”

Master Electricians Australia, another Safer Solar stakeholder, says serious injury or death from rooftop PV systems is preventable during disasters, and it supports the call for improved safety measures.

“Thankfully, we have only had a handful of major floods since Australia’s solar boom began around 15 years ago,” says Master Electricians Australia CEO Malcolm Richards. “What that means is we’ve been lucky so far in avoiding any serious injury or death from live solar panels during an emergency.

“However, without urgent action it can only be a matter of time until we do face a tragedy. In any flood, Master Electricians always steps up to warn homeowners of the dangers of climbing onto a roof, even if power has been switched off.

“In the short-term, it would be helpful for governments to join that effort with an information campaign ahead of flood season.

“In the longer term, we need to address this through legislation and upgraded standards, and we need our state governments and regulators to step up.”

Tigo Energy is another Safer Solar member, and the company’s senior APAC director, Jeff Routledge, says rapid shutdown is just one of the benefits of module-level power electronics (MLPE), devices that can be incorporated into a solar PV system to improve its performance in certain conditions.

“MLPE allows panel-level remote monitoring and management, which means quicker and safer restoration of solar energy to homes after disaster strikes,” he says.

“We’ve had significant disasters during the past two years, including hailstorms, bushfires and flooding. When these catastrophes occur, people need to decide on priorities, which is where remote monitoring pays off. It allows you to review solar PV systems, audit their status and safety, and prioritise what to do next without having to send an electrician onsite.”