AEMO warns big batteries to expect breakfast call to protect the grid from rooftop solar juggernaut

The Australian Energy Market Operator has outlined the controversial new protocols that could require big battery projects in Victoria and South Australia to empty their storage and sit on standby if need to protect the grid from having too much rooftop solar.

The new protocols were flagged more than a month ago as part of new measures adopted by AEMO to address minimum system load, when the output of the nation’s still burgeoning numbers of rooftop solar system make it difficult to manage the grid.

The energy market is used to warnings of insufficient supply, through AEMO’s “lack of reserve” notices, particularly in the middle of heatwaves or when there is a large amount of capacity offline due to planned or unplanned maintenance.

AEMO has now started to issue low level “minimum system load” notices, particularly in Victoria, warning that operational demand could fall so low there will not be enough “controllable” assets – such as coal, gas, hydro, wind and solar” on line to deal with any contingencies that may arise.

This week it has issued several new MSL notices, including what is believed to be the first MSL2 notice for this coming Sunday, although it has already been withdrawn.

The new protocols are seen as preferable to the blunter instruments of solar switch-offs – now introduced in most states, with NSW expected to follow next September – but they have caused concern among battery storage owners and operators because it may mess with the business models and operational plans.

The details of the new guidelines were published this week. Broadly, if AEMO sees the potential of a minimum system load incident, it will publish a warning, maybe a week in advance, advising of the levels in operational demand that will trigger the next actions.

AEMO says its first priority will be to cancel any network augmentations, and constrain large scale wind and solar farms, if they are still operating. (Periods of low demand often coincide with negative price events which usually forces wind and solar to shut down).

It will also constrain any “scheduled” generation – coal or gas – if their units are not needed to provide the minimum amount of system services.

If all that is not enough, the call will then go out between 7am and 9am to the owners and operators of the big batteries operating in Victoria and South Australia – those with more than 15 MWh capacity and with bidirectional units – to start discharging so they are ready to charge at a moment’s notice, if needed, between 9am and 1pm.

The option for a solar switch off is still there, although the local network operators say they will need at least 90 minutes notice to put that into effect, although that timeframe may shorten as more sophisticated measures are introduced.

The MSL notices are expected to be issued during spring and summer, but may not be a long term issue as more battery storage is built into the system, and when there is more electrification of homes, business and transport.

This is despite the continuing record level of rooftop solar installations as consumers seek to protect themselves from high retail electricity prices.

Michael Gatt, AEMO executive general manager operations, told Renew Economy in September that the need to direct batteries will decrease as more batteries are commissioned and as better rooftop solar controls become available.

“We’re aware that high contributions of rooftop solar coinciding with certain system conditions needs to be carefully managed to ensure electricity reliability and grid security while managing power system risks,” he said.

In a recent article, the Clean Energy Council’s Christiaan Zuur wrote about his concerns with the process.

“While energy storage systems offer a logical solution here, there is a key problem with AEMO’s approach. To provide this response, batteries need to be at a low state of charge and ready to soak up energy when needed. However there are currently no price signals to incentivise this to occur,” he wrote.

“Another issue is that on the other side of the ledger, there are several coal units running at their minimum levels. We are at a place where those aggregate minimum levels of coal generation are butting up against the minimum levels of demand. And batteries are being asked to fix the problem.

“The irony is a little bitter. Directing batteries to charge, so that coal generators can stay online, is a perverse outcome. It’s obviously inconsistent with a pathway to decarbonisation. But it’s also likely to negatively impact on the ongoing business case for battery investment.” 

For more information, see Renew Economy’s Big Battery Storage Map of Australia