South Australia is either a cautionary tale or a success story, depending on who you ask and what decade they’re stuck in. But if you look at the actual data — not the opinion pages — what’s happening in SA is remarkable and has direct implications for every other state.

The numbers are staggering

South Australia now gets over 70% of its electricity from renewables. Rooftop solar alone provides about 15% of the state’s total generation. On some spring days, the state runs entirely on renewable energy for hours at a stretch.

The big battery at Hornsdale (originally Tesla’s famous 100MW installation, now expanded) has paid for itself multiple times over through frequency control services. And SA’s wholesale electricity prices, which spiked during the 2016-2017 crisis, have been among the lowest in the NEM in recent years.

That’s the headline story. But the detail is more nuanced and more interesting.

What’s actually working

Rapid frequency response from batteries. Before the big battery, SA relied on expensive gas peakers for frequency control. Now, batteries respond in milliseconds rather than minutes, doing the same job for a fraction of the cost. This has saved consumers hundreds of millions of dollars and dramatically improved grid stability.

Rooftop solar as infrastructure. SA treats residential solar not as a curiosity but as genuine grid infrastructure. AEMO models it. SAPN plans around it. The VPP programs in SA are the most advanced in the country. This mindset shift is important and other states are slowly following.

Interconnector improvements. The expanded interconnector to Victoria (Project EnergyConnect) provides a safety valve for times when SA has too much or too little renewable generation. Grid islands are risky. Connected grids are resilient.

What’s been challenging

Minimum demand events. SA has had to manage situations where rooftop solar output exceeds total state demand. AEMO has implemented emergency protocols for these events, including instructing grid-scale solar and wind to reduce output. In extreme cases, they’ve discussed requiring residential solar inverters to be remotely curtailable.

This is a real tension. Homeowners installed solar with the reasonable expectation that they could export freely. Being told their system might be throttled remotely doesn’t sit well. The engineering argument for curtailment is sound, but the social contract implications are tricky.

Gas still needed for reliability. Despite the renewable dominance, SA still fires up gas generators during extended cloudy periods, high-demand summer evenings, and when interconnectors are constrained. The “last 20%” of decarbonisation is much harder than the first 70%, and gas plays an ongoing reliability role that renewables and batteries can’t fully replace yet.

Cost distribution questions. Who pays for grid upgrades needed to accommodate all this renewable generation? Currently, all SA electricity consumers pay through network charges, including renters who don’t have solar and can’t access the savings. This equity issue isn’t unique to SA but it’s most visible there.

Lessons for other states

Queensland, NSW, and Victoria are all heading in the same direction as SA, just five to ten years behind. Here’s what they should learn:

Invest in batteries early. SA’s battery storage has been transformational. Other states should be deploying both grid-scale and distributed batteries now, not waiting until they hit the minimum demand problems SA experienced.

Plan for curtailment. It’s coming everywhere. Designing smart curtailment mechanisms that are fair and transparent is better than implementing emergency protocols in a crisis. New solar inverter standards (AS/NZS 4777.2:2020) already require remote disconnect capability. Use it thoughtfully.

Don’t forget equity. The benefits of the energy transition accrue disproportionately to homeowners who can install solar and batteries. Renters, apartment dwellers, and lower-income households risk being left behind. Community solar, social housing programs, and tenant-friendly policies need to be part of the plan.

Interconnection is insurance. States with more interconnection have more resilience. The business case for new interconnectors is strong and getting stronger.

My take

SA has made mistakes along the way — the 2016 blackout was a genuine crisis, partly caused by inadequate planning for renewable variability. But they’ve also done something extraordinary: built a renewable-dominated grid in a major developed-world jurisdiction and made it work.

The rest of Australia should stop debating whether renewables can power the grid and start learning from the state that’s already doing it. The lessons are there for anyone willing to look.