Solar systems in the US are about the double the price of Australia’s but several aspects compromise the safety of Australian systems, including the mandating of DC isolators.
Energy technology company Enphase Energy’s A Comparison of Australian and US Residential Solar Markets report noted that Australia has struggled with solar-related fires in the past decade.
According to the Fire Investigation and Research Unit superintendent of Fire and Rescue NSW, solar-related fires in the nation have increased five-fold in the last five years alone.
To address this issue, the Australian Standard AS/NZS 5033 mandated the use of DC isolators for solar systems with string inverters in 2012. DC isolators are safety mechanism switches used to disable dangerous high-voltage DC between the solar array and the inverter.
Unfortunately, as the report warned, DC isolators are easily prone to degradation and malfunction that causes system fires, which is ironic given the tool is intended to improve safety instead.
“In NSW alone, there is a 20 per cent increase in fires related to solar panels since last year, with more than 50 per cent caused by DC isolators,” the report said.
“Since they’re connected to high-voltage systems, DC isolators also pose an electrocution risk for maintenance or emergency personnel. Australia is currently the only country that requires DC isolators, but this is currently under reconsideration due to safety concerns.”
Several common brands of DC isolators have already been recalled due to fire safety reasons.
“Lagging safety regulations still allow the use of high-voltage DC systems, which are responsible for two solar-related fires each week,” the report continued.
The report also identified that while US incentives and rebates for installing solar systems may be similar to those in Australia, they are far less lucrative due to the differences in how both countries manage its solar system safety.
“Australia makes it easier for homeowners to install rooftop solar, but at what cost,” the report asked.
“In the US, requirements for solar safety have been added into state and municipal electrical, building and fire codes, as well as permitting and inspection processes.
“All electrical contractors must follow National Electric Code (NEC) guidelines, which are updated every three years and adopted by most states. Within these guidelines are some strict requirements on weatherproofing enclosures, rapid shutdown in the case of grid outage, wiring, and much more.”
Rapid shutdowns are mechanisms that are important for safety because they automatically lower voltage and de-energise solar modules in the event of an outage or fire.
This also significantly reduces the risk of electrical shock to fire fighters and first-responders addressing these solar-related fire events.