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.
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.
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.
AEMO is becoming increasingly concerned about the growing share of rooftop solar. It says this creates opportunities for creative thinking and new technologies – in storage, demand management, software development and virtual power plants – but it is also worried about its impact on frequency control, inertia, and system strength.
This week it declared a shortfall of inertia in the state, and both AEMO and the state government are worried about the risks to grid security this spring – when rooftop PV output is high and demand can often be low – and should the main transmission link fail again, and before the planned new synchronous condensers are installed.
The South Australia government says it understands the industry’s concerns, and is working to address them as quickly as it can. It says the new measures must be introduced in September because if delayed to the end of the year that could add 100MW of new capacity that may not meet the standards. That could make the difference when the next major network fault appears.
South Australia’s energy minister Dan van Holst Pellekaan has said tougher measures are preferable to putting a stop to new installations. The government says it believes it can double the amount of rooftop solar in the state if the new measures are introduced.
Government sources say a list of approved inverters will be made available as soon as possible. Inverter manufacturers will be asked to ‘certify” their product if testing cannot be completed on time, and will be asked to “make good” any issues that may arise. Existing contracts will be grandfathered, but only those signed before August 10.
There will also be guidelines around the ability to impose removed “shedding’.
Households installing new systems will be asked to nominate an “agent” when signing the installation contract who will exercise that remote control on behalf of AEMO. That could be virtual power plant operators, metering companies or monitoring companies.
“There are lots of different views about whether it is done best through an inverter or a dual meter,” a government insider said. “You can use whichever technology, you just need an agent.”
Solar tariffs have also been changed and now require retailers to offer cheap power in daytime hours, an incentive to create a ‘solar sponge’ that might encourage more battery storage, and/or the shift of electric water heaters to the daylight hours rather than the middle of the night.
There is also a separate push in some sectors to impose an “export tariff”, the so-called “solar tax”, although this appears unrelated to the system security issues identified by AEMO and the state government.
Some consumer bodies have thrown their support behind these initiatives, as long as current and sometimes arbitrary limits on solar exports and solar installations are lifted, and any tariffs are moderate and imposed only on very large exports. They note the cost to networks to upgrade their systems to accommodate rooftop solar is relatively small, about one per cent of total network costs.
Update: A government spokesman said in emailed statement later:
“The Office of the Technical Regulator (OTR) has received a number of applications to act as agents for remote management that are being assessed by the OTR.
“The OTR is pleased that it has received test results from a range of inverter manufacturers that indicate that they already meet the voltage ride through standard.
“When approved, agents and compliant inverters will be announced progressively on the Department website over coming weeks.
“With regard to smart meter wiring, the OTR has been undertaking targeted consultation to develop a draft guideline that will be released in the next week for broader consultation.”