Solar, batteries, and VPPs are set to lead the way as Western Australia’s isolated grid steadily switches off thermal generators. 

Four million and more than 25 gigawatts (GW); these are big numbers and they represent meaningful change. Australia’s solar industry serving the rooftop segment should be mightily proud of this world-leading achievement. 

On Nov. 14, the Clean Energy Council announced that Australia had achieved four million rooftop solar systems – for a total capacity of (you guessed it) 25 GW. That’s more generating capacity in Australia than coal – a massive milestone.

In announcing the development, the Clean Energy Council’s Kane Thornton likened rooftop solar to the “hills hoist” of the 21st century. And he gave a most welcome shoutout to the crews on the roofs that made it happen. 

“Installers are the engine room of this solar revolution and with most being sole traders or small business operators, this is good news for jobs, for economic prosperity and for communities and families, everywhere,” said Thornton. And he’s right. 

New WA record

But the four-million milestone wasn’t the only one to turn heads this month. Just a few days later in WA, a pretty remarkable moment occurred on the South-West Interconnected System (SWIS).  

On Nov. 17, the SWIS achieved a new renewable-energy milestone. Around 90 minutes past midday, a tick over 85% of the electricity on the network came from renewables. And rooftop solar was the real star accounting for 72.3% of total generation. 

This is a great achievement and demonstrates the massive role for rooftop PV in powering the major population centre in the southwest of WA today and into the future. And it is particularly notable for what was missing. While rooftop PV was supplying almost three-quarters of demand for homes and businesses at that time, coal generators were responsible for only 7.1%, and gas 7.4%. 

With such a small amount of fossil-fuel powered generation on the SWIS, a new record for “minimum synchronous generation” was achieved on the same day. While great news for emissions, it creates challenges in ensuring electricity system stability. 

The SWIS is the world’s biggest isolated electricity network. While we’re used to seeing South Australia rack up similar records, the state is at least a part of the National Electricity Market (NEM), and projects to enhance is connectivity to other states are underway. 

In WA, it’s a grid unto itself – and the system engineers and regulators can’t rely on or blame anyone else if the lights go out. It’s like a giant microgrid, in one sense. 

Brad Smart, who is the principal policy officer at government agency Energy Policy WA singled out the achievements behind the scenes that allowed the record set on Sunday happen. 

“It is the result of work by many people over time to update of standards, visibility, forecasting, systems, and operations capability as well as the addition of utility scale storage – which meant market rule changes,” Smart wrote on LinkedIn. 

And he’s spot on. What Smart points to is that achieving such a huge contribution from rooftop PV generation, and such a tiny amount of synchronous generation, represents a departure to how the electricity network was managed in the past. Maintaining electricity system stability while traditional generators shut down represents another world-leading endeavour, and one that Australian regulators are tackling head on. 

Engineering Roadmaps

In August, the Australian Electricity Market Operator (AEMO) published its SWIS Engineering Roadmap. The goal of the roadmap is to ensure that the preparatory studies and then measures are taken to allow the SWIS to run without synchronous generation with ever growing frequency – essentially on 100% renewables.

Without getting bogged down into the details of what is a very technical report, AEMO sets out the capabilities that must be addressed if the coal and gas generators can be switched off. These include voltage control, system strength, transient and oscillatory stability, frequency stability and inertia, and ramping capability. These capabilities are, at present, served by traditional generators. They will have to be replaced by "a combination of renewable generation, energy storage and/or network assets” AEMO concludes. 

The Engineering Roadmap sets out regulatory and technical priorities to achieve this goal. And it is encouraging to see the breath of solutions being incorporated into planning.

One such move, albeit on a national level, is that on Nov. 9 Standards Australia updated the national technical standard AS4777 relating to vehicle-to-grid or vehicle-to-home charging for EVs, paving the way for both applications. The logic behind the move being that the batteries of parked vehicles could help support the grid, or provide backup power for households. 

Federal Energy Minister Chris Bowen, in announcing the standards update, said that the government hopes that bidirectional EV chargers will be available by the end of the year to facilitate this change. “What that means is that no longer will charging be a one-way street,” said Bowen. 

Power of DERs

Bowen also noted that the EV battery will far outsize residential batteries in terms of capacity – demonstrating that cumulative they could make a sizeable contribution to the electricity network. And while true, both EV and household batteries are set to make a power impact, as rooftop PV has proven through its years of steady progress. 

In fact, there are reasons to believe that AEMO may be underestimating what rooftop PV, batteries, and grid-connected EVs – distributed energy resources (DERs) – can do to manage system stability as gas and coal generators exit the SWIS. 

In May, the analysts at the Institute for Energy Economics and Financial Analysis (IEEFA) published research showing that DERs may play a much larger role in Australia’s future energy mix. If this contribution by DER is overlooked, IEEFA warned, “AEMO risks over-estimating how much large-scale generation and new transmission will be necessary.”

This may also be true when it comes to ensuring system stability as synchronous generators exit the SWIS. Endeavours like Western Power’s award-winning Project Symphony has gone some way in filling this expectation gap through demonstrating what Virtual Power Plants (VPP) can do even when a diversity of power electronics hardware is by the different households. 

At the end of the day, there’s a growing argument that the way planners should be thinking about WA’s southwest electricity system is as if it is a giant VPP. There are few signs that the appetite for rooftop solar is abating and batteries and EVs are likely to surge into the marketplace. Instead of underestimating DER, it may well make sense to put it to work as a network and for network stability. 

It’s an exciting time, that’s for sure. And it should be remembered that it is on progress driven by the people and companies getting DERs installed in homes throughout the SWIS. Sometimes overlooked, Australia’s army of solar and battery installers are not to be underestimated.