“Chaos and confusion” as regulators fast-track rules to switch off solar PV

The Clean Energy Council has warned of “chaos and confusion” in the rooftop solar industry, particularly in South Australia where authorities are scrambling to define and put in place new standards and protocols to help manage the growing share of rooftop PV.

The warning came as the solar industry braces for several significant changes affecting solar tariffs, and inverter and metering standards, and a push to ensure they have “ride through capabilities” to withstand major system faults, and are also able to be switched off en masse to help keep the grid secure.

It’ already affecting customers, with installations signed after August 10 potentially being affected by new standards and approved equipment that are yet to be finalised.

South Australia finds itself at ground zero because no other state has such a large share of rooftop solar (12.3 per cent of generation over the last year, and up to two thirds in some instances), and is threatening to push minimum grid demand down to levels that the Australian Energy Market Operator says are difficult to control.

Within a couple of years, AEMO says, minimum demand at times could be pushed below zero. This creates issues, it says, because it means less space for other generators to provide traditional services essential to keeping the grid secure.

See: South Australia: The first big grid where rooftop solar could eliminate all demand

But the solar industry says it is being kept in the dark over the details of the regulations, which – to its surprise – are now supposed to come into force in South Australia in four weeks, by September 28, rather than the end of the year as previously thought. But the list of approved inverters, the rules around solar shedding, and new wiring codes have yet to be released.

“We still do not know the rules around switching customers’ systems on and off,” the CEC says in its email to members this week. “(We still don’t know) how SA Power Networks will be involved, what equipment can be used to do it, what customers will be expected to pay for this ‘service’ and what it might mean for warranties and consumer protection.

“To make matters worse, there are no inverters approved for connection to the SA Power Networks grid after September 28. Right now, the best advice we can give SA businesses is to manage their inverter inventory carefully to minimise the risk of being caught with redundant stock.”

The fast-tracking of new standards in South Australia follows the release in June of a new report by AEMO and the state government which flagged major risks in the state as the share of rooftop solar grows.

It is particularly concerned about what happens when the state is “islanded” by faults in the main transmission line, which happens often enough, and how it can control rooftop solar in those circumstances.

In a draft interim standard published this week that will eventually apply across all states, AEMO says that up to 40 per cent of rooftop solar systems can suddenly disconnect  because the inverters are unable to ride through system faults. In South Australia, that amounts to 500MW of capacity that could suddenly be lost, a major threat to the system in such a small grid.

To address this, AEMO is seeking an update of standards AS4777, to ensure that testing occurs that confirms an inverter’s ability to ride through system shocks. It expects this to come into effect within six months.

The problem for South Australia, and its accelerated deadline, is that there are only two testing labs in Australia, and one is currently not operational due to equipment problems exacerbated by the Covid-19 impact.

In the past, AEMO could respond to the loss of a major generator by asking the local network to briefly black out a suburb or suburbs, so reducing load to help balance the loss of a generator.

But now the some areas are net producers because of the amount of rooftop PV, this could actually make things worse by eliminating a generator rather than load – which is why AEMO is pushing to have the power to disconnect rooftop solar PV rather than whole suburbs.  It insists, however, that this will happen in the “very rare” event where it has no alternative.

It appears the state government is looking to do this through either inverters or new “dual element” smart meters. The problem in South Australia arises, the industry says, is that the wiring guidelines for the meters have not been released by the Office of the Technical Regulator. “We have been blindsided,” said on industry source.

There are also questions whether dual element meters are the right way to go, and the potential cost they might impose on re-wiring household circuits, and about who will be the “agent” of the instruction to disconnect, and on the protocols of how this will be put into place.