AEMO released their updated Integrated System Plan last month, and the media coverage has been predictably focused on the big-ticket items: Snowy 2.0 delays, offshore wind timelines, and transmission line costs. All important. But what nobody’s talking about is what the ISP says about people like you and me — the millions of Australians with panels on our roofs.

I’ve spent the weekend reading the actual document (so you don’t have to), and there are some genuinely interesting signals buried in the data.

Rooftop solar isn’t slowing down

AEMO’s central scenario projects rooftop solar capacity to roughly triple by 2050. We’re currently sitting at about 20GW of installed rooftop capacity nationally. The ISP expects that to hit 60-70GW in their step change scenario.

That’s extraordinary. It means AEMO is banking on rooftop solar being a major pillar of the energy system, not just a household cost-saving measure. And they’re planning grid infrastructure around that assumption.

The “minimum demand” problem is getting real

Here’s the part that should concern solar owners. On sunny days in spring and autumn — mild temperatures, lots of sun, low air conditioning load — grid demand drops so low that it creates stability problems. AEMO calls this the “minimum demand” challenge.

In South Australia, minimum operational demand has already gone negative on some days. That means rooftop solar is producing more power than the entire state needs. Victoria and Queensland aren’t far behind.

Why does this matter for you? Because when the grid can’t absorb more solar, the solutions include curtailing exports (reducing what your system sends to the grid) or dropping feed-in tariff rates to zero or even negative.

We’re already seeing this. Some retailers are moving to time-of-export pricing, where your feed-in rate varies based on when you export. Midday exports are worth less. Late afternoon exports are worth more.

Batteries are the ISP’s answer

AEMO’s plan relies heavily on distributed batteries — both household and community scale — to soak up excess solar during the day and discharge during evening peaks. The ISP’s step change scenario has distributed storage growing from about 2GWh today to over 30GWh by 2050.

This isn’t just a nice-to-have in AEMO’s modelling. It’s essential to making the grid work. And it has policy implications. I’d expect to see more battery incentive programs in the coming years, similar to what Victoria’s done with its battery rebate.

If you’re a solar owner without a battery, this is the trajectory to watch. Your export income is going to keep declining, and batteries are going to become increasingly important for capturing the full value of your solar generation.

Virtual power plants get a bigger role

The ISP explicitly models VPP participation growing significantly. If you’re not familiar, a VPP aggregates hundreds or thousands of home batteries and coordinates them to provide grid services — think of it as your battery helping stabilise the grid in exchange for payments.

Tesla’s VPP program in South Australia has been the highest-profile example, but others are emerging. AGL’s VPP, Reposit Power, and Amber Electric’s SmartShift all offer some version of this.

The economics are still early-stage for most participants — you might earn $200-500 per year from VPP participation — but AEMO’s projections suggest this will become a more significant income stream as the grid becomes more dependent on distributed resources.

What I think rooftop solar owners should do

Based on the ISP’s direction, here’s my practical advice:

Maximise self-consumption. The days of making money from solar exports are fading. Run your dishwasher, washing machine, and pool pump during solar hours. Heat your hot water during the day if you’ve got a heat pump.

Seriously consider a battery. Not necessarily today, but have a plan. When battery prices cross the threshold where payback periods drop below 7-8 years for your situation, pull the trigger. We’re nearly there for many households.

Look into VPP programs. If you have or get a battery, signing up for a VPP is essentially free money. The grid needs your battery more than you might think.

Don’t panic about curtailment. Yes, export limits and dynamic curtailment are coming. But they only affect your exports, not your self-consumption. A well-designed system still saves you thousands per year even if your exports are occasionally curtailed.

The ISP is a planning document, not a crystal ball. But the direction is clear: rooftop solar is here to stay, batteries are becoming essential, and the relationship between solar owners and the grid is evolving fast. Stay informed and you’ll be fine.