14 GW of Grid Batteries Are Coming. Here's What That Means for Your Home Battery

A thread on r/australia recently dropped some numbers that stopped me mid-scroll. Australia now has 17 gigawatts of battery capacity either online or on its way across the National Electricity Market. Of that, 14 GW is under construction right now, hitting the grid in the next 12 to 24 months. Queensland alone just switched on over 1.7 GWh of grid-scale storage in a single fortnight.

For context, our entire national demand sits around 22-24 GW. We're building enough battery storage to handle a genuinely massive chunk of that.

Meanwhile, over on r/solar, Australians are posting about home battery payback periods of three years and subsidies that cover half the cost. One user, u/crispypancetta, summed it up: “Payback on battery now is around 3 years give or take, better than solar.”

So which is it? If the grid is about to be flooded with cheap storage, should you still buy your own? Or are you about to invest in something the grid will make redundant?

Let's work through it.

Grid-scale batteries do the same thing your home battery does, just at industrial scale. They charge during the day when rooftop and utility solar is flooding the market and electricity is dirt cheap. Then they discharge during the evening peak (5pm to 9pm) when the sun's gone and everyone's home cranking the aircon.

Right now, that evening peak is where gas plants make their money. As we covered in our piece on why your power bill is still high, the NEM works on a marginal pricing system. Every generator gets paid the price of the most expensive one needed to meet demand. During those evening peaks, that's almost always gas. And gas doesn't come cheap.

Normal wholesale prices sit around $100-200/MWh. But during peak events, they can spike to $10,000/MWh. Sometimes $20,000. Those spikes are what keep bills high even though daytime solar has made midday electricity practically free.

Grid batteries are designed to kill those spikes. Charge at $30/MWh during the day, discharge at $300/MWh in the evening, pocket the difference. Every megawatt of battery that fires up is a megawatt of gas that doesn't get called. Less gas means lower peak prices. Lower peak prices means.... eventually.... lower bills. The Tarong and Swanbank mega batteries that just went live in Queensland are doing exactly this, 550MW of storage soaking up cheap daytime solar and dispatching it into the evening peak.

This is the part most coverage of grid batteries glosses over. And it matters if you're trying to figure out where electricity prices are actually heading.

Right now, gas peaker plants fire up every evening when the sun goes down and demand surges. They set the wholesale price because they're the most expensive generation that gets called. Grid batteries are designed to undercut them: discharge stored solar at, say, $300/MWh instead of needing gas at $10,000/MWh. That's great for consumers.

But here's the twist. Gas plants won't disappear overnight. They'll run less often, sure. But they still have fixed costs: maintenance, staff, fuel contracts, grid connection fees. Those costs don't shrink just because they're dispatched less. So when gas does get called (during a heatwave, a transmission fault, a cold snap when batteries are already flat) it'll bid even more aggressively to recover those fixed costs in fewer hours.

Think of it like a taxi driver who used to work eight-hour shifts but now only gets called for two hours a day. They'll charge a lot more per ride. Gas plants will do the same. Fewer dispatches, higher prices per dispatch.

The other big shift: negative daytime prices will largely disappear. Right now, wholesale prices go negative around midday because there's more solar than the grid can absorb, and coal plants bid below zero just to keep running (shutting down and restarting a coal plant costs millions). Once grid batteries are soaking up that midday surplus and coal plants retire entirely, that oversupply problem evaporates. Midday prices will stabilise above zero, probably in the $30-80/MWh range, as batteries become the buyer of last resort.

Net result? The overall price curve gets flatter. Fewer extreme lows, fewer extreme highs. More predictable for everyone. But those rare spikes when gas still gets called? They could be even wilder than what we see today. Which, incidentally, is exactly when VPP programs pay your home battery the most.

This is the worry. If grid batteries flatten out those evening price spikes, the gap between “cheap daytime solar” and “expensive evening peak” gets smaller. And that gap is exactly where home battery owners make their money.

Think of it like this. Right now, electricity pricing is like the surf at Bondi: big peaks, deep troughs, plenty of energy to ride. Grid batteries are going to smooth that out. Not flat like a lake, but more like Manly on a calm day. Still waves, just smaller ones.

If you're on a time-of-use tariff or a wholesale spot-price plan like Amber Electric, smaller price swings mean less profit from charging cheap and discharging at peak. That's real. No point pretending otherwise.

But here's what that framing misses.... arbitrage was never the only reason to get a home battery. And for most households, it wasn't even the main one.

1. Self-consumption doesn't care about grid prices

The biggest value of a home battery has always been self-consumption. You store your own solar during the day and use it at night instead of buying from the grid. Every kWh you use from your battery is a kWh you don't pay 25-35c for at retail rates.

Grid batteries don't change this equation at all. Wholesale prices could drop to zero and your retail rate would still be 25-35c because of network charges, retail margins, and daily supply fees. Your battery shields you from all of that. That alone is worth $800-$1,200 a year for most households, though extreme heat can affect battery performance, so factor that in. Use our battery calculator to see the numbers for your situation.

2. VPP earnings might actually go up

Here's an interesting twist. As grid batteries smooth out the predictable evening peaks, the unpredictable spikes become even more valuable. Heatwaves, coal plant trips, transmission faults, these still cause wholesale prices to go through the roof. And when they do, VPP programs pay your battery to discharge into the grid at premium rates.

Grid operators are going to need more distributed flexibility, not less, as the grid gets more complex. Your home battery enrolled in a VPP is genuinely useful infrastructure. And you get paid for it. If you haven't looked into VPPs yet, our VPP vs feed-in tariff breakdown explains how the earnings compare.

3. Blackout protection is worth more than people think

South Australia has already proven that an entire state grid can run on rooftop solar. That's remarkable. But it also means the grid is running on thinner margins than it used to. More renewables means more variability. Grid batteries help with that at scale, but they can't stop a tree falling on your local power line.

A home battery with backup keeps your lights on, your fridge cold, and your internet running when the grid goes down. Try putting a dollar value on that the next time there's a summer storm and your street goes dark for 12 hours.

4. The subsidies won't last forever

This is the one that makes the timing argument. As u/ol-gormsby noted on Reddit: “There's a subsidy available at the moment that means you'll only pay about 50% of the price. It's so popular there's a four-month waiting list.”

The federal battery rebate plus state incentives are making batteries genuinely affordable right now. We're seeing 40kWh systems for around $7,000 after subsidies. Smaller 5kWh systems from $5,600. At those prices, the payback maths is hard to argue with.

But governments don't subsidise things that everyone's already buying at full price. Once battery adoption hits a certain threshold, or the budget gets tight, those rebates will taper off. The four-month waiting list tells you how popular they are. Take the rebate quiz to see what you qualify for before the window narrows further.

Let's put some rough numbers on it. A typical household with solar and a 10kWh battery in 2026:

Against a post-subsidy battery cost of $5,000-$8,000, that's a payback of roughly 3-5 years. On a system warranted for 10+ years. Even if grid batteries shave 20-30% off the arbitrage component over time, the self-consumption and VPP value keeps the maths firmly in your favour.

Run the numbers for your household with our payback calculator. The inputs that matter most are your current bill, your solar system size, and which tariff structure you're on.

Buy now if: You've got solar, you're exporting heaps during the day at a shrinking feed-in tariff, and your evening bills are still painful. The subsidies are live, the payback is short, and you'll be earning VPP income while the grid batteries are still being bolted together. Compare home battery options, check the current prices, and read the buying guide to get started.

Wait if: You don't have solar yet. Get the panels first. They're the foundation. A battery without solar is like buying a surfboard before you've found a beach.

Think carefully if: You're in an apartment or rental where you can't install anything. Grid batteries improving the wholesale market is genuinely your best hope for lower bills. Push your retailer to pass those savings on.

Fourteen gigawatts of grid-scale batteries is a big deal. It's going to reshape the electricity market, push gas to the margins, and eventually bring peak prices down. That's good for everyone.

But “eventually” doesn't help your next quarterly bill. And even when those grid batteries are fully online, your retail rate will still include network charges, supply fees, and a healthy retail margin. The people paying the least right now are the ones who've already got a battery on the wall.... storing their own solar, earning from VPPs, and barely touching the grid.

Grid batteries are the solution for the system. A home battery is the solution for your house. They're not competing. They're complementary.

And the best ROI goes to the people who buy while the subsidies are still generous and the waiting list is still just four months, not twelve. Check what rebates you qualify for, read the battery basics guide if you're still getting your head around the tech, and run the payback calculator with your actual numbers.

The wave is coming. Might as well ride it.