Continuing Push For Rooftop DC Isolator Requirement Review

Rooftop DC isolator

Image via ProductSafety.gov.au

There is a growing call for an end to the very unpopular rooftop isolator requirement for solar power system installations in Australia.

What Is A Rooftop DC Isolator?

Pictured above, a rooftop DC isolator is manually operated switch situated adjacent to a solar panel array that shuts off DC current between the array and the solar inverter. It was intended as an additional safety mechanism as there are also isolator switches at ground level adjacent to the inverter or enclosed within the inverter itself.

Solar power system owners don’t have a choice as to whether a rooftop isolator is installed – it is currently required. The reasoning behind the requirement was primarily to help better protect emergency services. But fires occurring in rooftop solar arrays have been rare and the use of the switch by emergency services, given its location, has apparently been even rarer.

What’s The Issue With Rooftop Isolators?

The isolators have caused more problems than they have solved, particularly when installed incorrectly.

“Rooftop DC isolators were made mandatory through AS/NZS 5033 in 2012,” states the Clean Energy Council. “Since then, rooftop isolators have been proven by inspection data to be the largest single source of PV system failure.”

An interesting point is while AS/NZS 5033 also applies in New Zealand, there is an exception for Kiwi installations in this regard – they do not require a rooftop DC isolator (nor is it a requirement in some other countries).

These devices have to operate for years in what is a particularly harsh environment. Aside from installation issues, there have been a number of recalls of various isolator devices due to issues such as the potential for water ingress or other faults that can cause the isolator to overheat and subsequently pose a fire/electrocution hazard. In some of the fires that have occurred in rooftop solar installations, the isolator has been the culprit.

It turns out that instead of reducing risks, rooftop isolators seem to increase risk and appear to be just an unnecessary potential point of failure in a solar power system.

Then Why Are They Still Required?

In a nutshell, because the Standards Committee is yet to undertake a full review and arrive at a decision as to whether the installation of rooftop DC isolators should continue to be mandatory; or other changes to the requirement made. In March last year, the CEC submitted a proposal to the Standards Committee EL-042 to review AS/NZS 5033 in relation to the devices and other issues, but that proposal wasn’t accepted.

The CEC says it is continuing to lobby all state electrical safety bodies and the review is gathering widespread support. The CEC states it is also communicating with emergency services to express its concerns regarding rooftop isolators and the need for a review.

Should You Be Worried?

If your solar power system was recently installed by a competent installer using good quality components, then there is little to be concerned about from a safety perspective. However, in SQ founder Finn Peacock’s book The Good Solar Guide, he strongly suggests getting an inspection and system test performed every five years by a suitably qualified professional. The rooftop isolator will be checked as part of this inspection.

The rooftop DC isolator situation is another reason why installation inspections need to be beefed up in Australia.

Update 18 June: in a communication sent yesterday afternoon, the Clean Energy Council stated members have given in-principle support to a proposal to also get rid of wall-mounted DC isolators by requiring the use of an isolator enclosed within the inverter, shifting some of the onus of responsibility from installers to product manufacturers.

In addition to pursuing changes to standards, the CEC says it aims to move the industry away from wall-mounted DC isolators through its product listing procedures and eligibility requirements associated with government rebates.

About Michael Bloch

Michael caught the solar power bug after purchasing components to cobble together a small off-grid PV system in 2008. He's been reporting on Australian and international solar energy news ever since.

Comments

  1. Chris Humphris says

    What everyone is missing is the exposure to extreme uv radiation in Australia. The plastic enclosures that the isolators are fitted cannot withstand the extreme temperatures and radiation. Stupid bureaucratic decision made by technically ignorants. The smart thing to do is to mount the isolator at ground level in a position protected from the elements.

  2. Bruce Armstrong says

    Roof mounted isolators have always been a stupid idea and it’s hardly surprising that they are the biggest source of system failures. It really makes one wonder about the competence of those that drafted the standards.

    I can understand why installers may like it, but the June 18 CEC proposal to move the isolators to inside of inverters also a really bad idea. There may be no way to replace an inverter without exposing live PV panel DC of several hundred volts or visiting the roof to make the panels safe by disconnecting some inter-panel leads.

  3. Mark Cerny says

    Australia should follow the USA on this and opt for rapid shutdown modular isolation. That is being able to isolate before panels combine power thus reducing the risks of DC voltages

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