Solar and battery giants unite to fight “outdated” inverter rule change

Some of the biggest names in the global solar and storage industry have stepped up their campaign against new rules for inverter controls in Queensland they say could potentially derail the state’s rooftop PV and home battery market.

In a letter sent to Queensland energy minister Mick de Brenni, Solar Edge, Enphase, Tesla, sonnen, Redback, SMA, Selectronic, and Fronius call for an alternative approach to the rooftop solar emergency backstop measure set to be introduced by Energy Queensland in just a couple of months’ time.

The rule requires new and replacement rooftop solar and battery storage systems of 10kW and over to be fitted with a basic generation signalling device to allow the state’s network operators to switch these PV systems off, remotely, if needed.

The eight companies – who between them have installed more than 85 million solar inverters, worldwide – argue this is an “outdated” mechanism whose introduction into the supply chain will cause more problems than it solves.

“The roll out will increase the cost of solar systems, potentially pushing up the cost of power to large consumers, compliance concerns, lack of functionality, the potential to damage consumer products as well as a risk of market disruption for solar and battery sales,” the letter says.

Old technology, new problem

As One Step Off The Grid has reported, Queensland – like South Australia and Western Australia before it – is seeking to solve the problem of large amounts of daytime solar exports sending operational demand so low as to threaten system grid security.

The solar industry well understands the need to address this issue, and with some urgency; but it sees no reason why Queensland – Australia’s most coal-dependent state – has opted to use mid-20th century technology for a 21st Century problem.

“While we recognise the need to act quickly in Queensland, we would recommend adopting the same approach as in South Australia,” the letter says, pointing to that state’s smart, software-based approach to solar switch-offs.

“We can collectively support Energy Queensland with an interim approach, similar to South Australia, where a registered agent receives a manual signal … and then uses [application programming interface] control functionality to manage all inverters within their portfolio,” the companies say.

“This alignment with the South Australian approach will reduce costs, increase compliance and could be applied retrospectively to a much larger pool of systems than just those after the proposed February start date.”

Clunky, costly and short-sighted

The letter goes on to detail a long list of concerns the companies – alongside other industry groups, including the Clean Energy Council – have with Energy Queensland’s current plan for rooftop solar control.

These concerns range from the lack of national alignment, to compliance and regulatory concerns, and the lack of functionality of using a basic on-off switch for solar.

One of the biggest concerns, however, is the cost to consumers of a technology that is soon going to become a “redundant mechanism,” once more modern techniques become the norm on the National Electricity Market.

“We believe that the costs to consumers will be much higher than the $70 cost stated by Energy Queensland,” the companies say.

“Our estimates are that the proposed backstop mechanism will increase costs to consumers by a minimum of $300 and up to $1000 per customer.

“We also have an additional concern that these costs will become a redundant mechanism once CSIP-AUS and the Dynamic Operating Envelope mechanism is introduced in Queensland,” the letter continues.

“Introducing an interim API based approach would reduce cost impacts for consumers and risks to the Queensland solar industry.”

Short-term fix with no future proofing benefit

Finally, the inverter and battery makers warn of the threat to system security that a basic solar on-off switch could have, despite its very purpose being to preserve system stability.

“With both the SA and WA processes, a customer’s inverter is not just simply turned off,” the letter explains.

“Turning off an inverter in the middle of the day without any visibility by the network of the behind the meter load will not only stop any PV export, it will also introduce all of the behind the meter loads on the network that the system has been supplying,” the letter says.

“This procedure will not only create a significant load onto the network but could also create voltage stability issues for commercial customers.

“The Energy Queensland proposal is a short-term solution that has no future proofing benefit,” the letter concludes. “We are happy to meet with you to discuss further.”