Enphase Energy has released a detailed report that raises questions about fire safety standards for Australian solar energy systems, including the use of a safety device that has become a common cause for solar system fires.

Entitled A Comparison of Australian and US Residential Solar Markets, the report found Australian solar energy systems cost about half the price of those in the US but it raised concerns about local safety standards.

“Australia makes it easier for homeowners to install rooftop solar… but at what cost?” the report said.

While US incentives for installing solar systems may be similar to those in Australia, they are far less lucrative.

“While the US and Australia have some common ground across incentives and rebates the two countries manage solar system safety very differently. 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,” the report said.

“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 a grid outage, wiring, and much more.”

Rapid shutdown - a standard feature of all Enphase microinverters - is an important mechanism for utility worker and homeowner safety because it automatically lowers voltage and de-energises modules in the event of an outage or fire. This significantly reduces the risk of electrical shock to firefighters and first responders when addressing solar-related fire events.

The Enphase report notes that Australia has struggled with a rash of solar-related fires during the past decade. “According to the Fire Investigation and Research Unit superintendent of Fire and Rescue NSW, solar-related fires in that state have increased five-fold over the last five years,” the report said.

To address this issue, the Australian Standard AS/NZS 5033 mandated the use of DC isolators for solar systems with string inverter in 2012.

A DC isolator is a switch that is intended as a safety mechanism to disable dangerous high voltage Direct Current (DC) between the solar array and inverter.

However, the report said DC isolators can easily degrade and malfunction, and have become a common cause for solar system fires.

“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. In addition, five common brands of DC isolators have been recalled.

"Lagging safety regulations still allow the use of high-voltage DC systems, which are responsible for two solar-related fires each week,” the report said.

Enphase Energy has used the report to point that its microinverters all come standard with rapid shutdown and they avoid high voltage DC by running low voltage Alternating Current (AC), the same current used by home appliances, from the roof down to the circuit panel box.

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