What you need to know about DC Isolators and rooftop fires

Ugh. Rooftop DC Isolators.

They are in the news again because when they fail, they can cause fires and with almost 3 million solar systems installed in Australia, there is an inevitable rise in the number of failures.

It is tempting to launch into the (warranted) debate about whether rooftop DC isolators are the best solution to ensuring safety, but I will resist that and instead just add three things for context.

Back in 1999 it was the safety authorities who mandated that these devices were first installed on a “massive” project run by Citipower in Victoria called the “100 solar Roofs” project which at the time was one of the biggest projects in Australia. The inclusion of rooftop isolators was mandated to ensure that linesmen or emergency workers could easily isolate the solar system in the event that they needed to. Over the years, it is Fire Brigades who argued for them and Standards Australia who deemed that rooftop DC isolators should be a mandatory requirement and it remains this way today.

Secondly, there have been recalls on rooftop isolators in the past. You can check on this list to see if you have a DC isolator that might be affected, but in most cases solar owners will already have been contacted or had theirs replaced.

And third, whilst the recent news articles have highlighted the concerning rise in incidents of fires associated with these isolators, in 2019 there were 139 solar related fires attended in New South Wales – which to be clear, is 139 too many.

However, it is worth noting that according to the latest data available from the Australian Photovoltaic Institute there were 635,411 solar systems installed over the thirteen years up to  September 2020 in NSW, with a total new installation rate of 101,224 systems in 2020 alone, according to the Clean Energy Regulator.

What this means statistically is that of all the solar systems ever installed in NSW less than 0.022% had a fire related incident in 2020 or put another way, 1 in 4,569 systems. It is also worth noting that in virtually none of these cases has a science-based forensic study been carried out to determine the root cause of the source of the fire (as far as I am aware) and I’ve studied the issue for years.

So, whilst we have a problem worthy of attention, it's worth remembering there are safety benefits provided by isolators, and solar wiring - just like any other wiring - needs protection.

If you are concerned about your rooftop solar isolator or have a system that hasn't been checked for a while, consider contacting your solar retailer or installer and getting a maintenance check.

How Solar Analytics can help

Recently, Solar Analytics installer Rod Grono from Western Sydney Solar advised us that our smart solar software with performance monitoring helped identify a system performance issue, which turned out to be caused by a faulty Rooftop DC isolator.

Rod was notified of reduced performance on a customer’s solar system, which in itself is a unique feature of Solar Analytics. Most monitoring systems will only advise you if the system shuts down entirely (and some don’t even do that!) but Solar Analytics cleverly predicts what the solar system should have produced based on real weather data and other system attributes, and compares that to actual production to calculate performance. If it is below normal expectations, we’ll tell the system owner and their solar installer or retailer.

In this particular case, Solar Analytics identified that although the system was still producing power, it was under-performing and prompted Rod to investigate further by alerting him. Rod was able to remotely analyse the system in great detail using our 5 Second Live data and quickly determined an emergency site visit was in order. When he arrived and started investigating the system, he found the isolator "arcing/smoking” - the precursor to combustion - and was immediately able to initiate a safe shutdown avoiding a potential catastrophe.

This is just one of the many benefits of smart solar software.

If you are considering buying a solar system, or already have one and don’t understand if it is performing properly, insist on smart solar software from Solar Analytics. We also recommend having your solar inspected every two years.

Our Business Development Director, Nigel Morris, counts more than 25 years of work in the solar industry but it's his positive approach to life, good-guy attitude and his cool electric motorbike that we really value. We love the nickname that his son game him - Captain Solar.

Solar Analytics
We are Australian Photovoltaic Engineers, Software Developers, Scientists, Solar Technicians and Designers, all passionate about sustainable energy and the power of solar.
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