A homeowner in Reservoir rang me last month with a quote in hand: 10kW of rooftop solar plus a 10kWh battery, bundled, $19,000 after rebates, five-year payback promised on the glossy sheet. I asked the obvious question. Payback on what, exactly — the whole system, or just the panels? He didn’t know. Neither did the salesperson, as it turned out, once I got him to call back and ask.
That’s the muddle at the centre of most home battery payback comparisons. Solar and batteries get sold as a single decision, one line item, one payback number. They’re not. They’re two completely different investments with two completely different rates of return, and mashing them together is how households end up disappointed three years in.
The maths installers actually see on a quote #
Strip the bundle apart and the numbers are stark. A well-sized rooftop solar system, string-sized properly to the inverter and pointed at anything better than due south, is still one of the best-returning pieces of household infrastructure you can buy. A 6.6kW system in most of the eastern states, after the upfront rebate delivered through the small-scale renewable energy scheme administered by the Clean Energy Regulator, lands somewhere in the $4,000–$6,000 range depending on the installer and the panel tier. Run the export and self-consumption numbers for a household that’s home during the day even a couple of days a week, and you’re typically looking at a four-to-six-year payback. After that, it’s free electricity for another fifteen-plus years of panel life.
A battery is a different animal entirely. Even with the federal Cheaper Home Batteries Program knocking a real chunk off the upfront cost since it started on 1 July 2025 — roughly 30 per cent off in the first year, tapering down over subsequent years as the subsidy rate steps down — a 10kWh unit installed today still typically costs somewhere in the $8,000–$13,000 range once you account for the inverter compatibility, the switchboard work, and whatever backup circuit the installer wires in. Set that against the fifteen or twenty cents a kilowatt-hour you’re saving by shifting stored solar into the evening peak instead of buying it back off the grid, and the payback stretches to eight, ten, sometimes twelve years — longer than a lot of battery warranties.
Rooftop solar: the payback that still stacks up #
I don’t think this is controversial among anyone who actually sizes systems for a living, but it bears saying plainly because so much of the marketing blurs it: solar alone is still the highest-returning thing on the roof. Feed-in tariffs have fallen a long way from where they sat a decade ago — I’ve written before about how thin those payments have become in how rooftop solar feed-in tariffs actually work in 2026 — but the real value was never the export credit. It’s the avoided purchase. Every kilowatt-hour your panels make and you use inside the house is one you didn’t buy at 30-odd cents. That’s the arithmetic that makes solar payback so reliable regardless of what the retailer pays you for the surplus.
The catch is sizing it right. Oversize the array relative to your daytime usage and your export limit — set by the local distribution network, typically 5kW per phase for a standard single-phase connection — starts clipping your generation at exactly the hours you’re producing most. I still see installers stringing a 10kW array onto a 5kW single-phase inverter with an export limit that throttles half the midday output straight back to nothing. It’s like fitting a garden hose to a fire hydrant and being surprised the pressure gauge maxes out. The panels are fine. The plumbing downstream of them isn’t sized for the flow.
Home batteries: where the numbers get murky #
Batteries earn their keep in a narrower, more specific way: time-shifting. They don’t make you a single extra kilowatt-hour. They just move the ones your solar already made from 1pm, when nobody’s home and the wholesale price might even be negative — I covered why that happens in negative electricity prices at midday: what they mean for you — to 7pm, when the kids are in the bath and the retailer is charging you peak rates.
That’s a genuinely useful function. It’s just an expensive one to buy, kilowatt-hour for kilowatt-hour, compared to just not needing the shift in the first place. A household with a pool pump, a work-from-home routine, or an EV charging during the day gets far less benefit from a battery than the marketing implies, because there’s less midday surplus left over to store. Meanwhile a two-income household that’s out from 8 till 6 is exactly the profile battery installers should be pitching hardest to — and, in my experience, often aren’t, because the panel-plus-battery bundle is an easier single sale than working out whether the customer’s usage profile actually supports it.
Export limits and the two-way meter problem #
Here’s a wrinkle that’s changing the calculation on both sides: two-way tariffs. A growing number of networks are now charging households for exporting solar during the graveyard hours of oversupply, alongside paying for exports at other times. It sounds punitive until you realise it’s a genuine bottleneck signal — the local wires just weren’t built for every second roof on the street shoving power backwards down them at once. A battery that soaks up your own midday export instead of pushing it onto a congested feeder starts to look more valuable under that pricing structure than it does under a flat feed-in tariff. It doesn’t flip the payback maths in the battery’s favour on its own, but it narrows the gap in the areas where two-way pricing has actually landed.
The federal battery rebate changes the sums, a bit #
The Cheaper Home Batteries Program is real money and it has shifted household decisions — installers I talk to say battery enquiries jumped noticeably once it landed. But I’d push back gently on the framing that’s crept into a lot of the sales conversation, that the rebate has made batteries pay for themselves as fast as solar does. It hasn’t. It’s made batteries meaningfully cheaper than they were. That’s a different claim, and on the numbers I’ve run for actual households — not brochure households with idealised, cloudless, always-home usage patterns — solar alone still wins the payback race by several years in most cases. The subsidy narrows a wide gap; it doesn’t close it.
Which one goes on the roof first — my verdict #
If someone rings me asking whether to do solar or a battery first, and the household hasn’t got solar yet, the answer isn’t close. Solar first, every time, sized properly to the switchboard capacity and the export limit your distributor allows, not to whatever number looks good on the sales sheet. Get that right, live with it for a year, and you’ll actually know your usage pattern — when you’re home, what draws the big loads, whether you’ve got room on the roof for more panels before you even think about storage.
A battery is the thing you add once solar’s already paying for itself and you’ve got genuine spare daytime generation to store, or once you’ve decided backup power during an outage is worth paying a premium for regardless of the financial payback — because that’s really a separate, non-financial reason to buy one, and a perfectly legitimate one, just don’t dress it up as an investment return. For context on how this all sits inside the bigger shift happening in Australian households, the Consumer Energy Resources roadmap is worth a read; it’s the policy scaffolding this entire decision sits inside.
I’ll admit a personal bias here. I’ve killed two attempts at a veggie patch out the back trying to get the timing right on watering, and I mention it because the lesson transfers oddly well: the thing that looks like the smart, integrated system on day one is usually just two separate jobs done in the wrong order. Get the fundamentals — the panels, the sizing, the export limit — right first. The clever add-on comes later, once you actually understand what you’re working with.
On the Default Market Offer and what households are actually paying without any of this gear, there’s more detail in the Default Market Offer and your power bill, and the broader question of who’s subsidising whom across the grid is one I keep coming back to in Who Really Pays For Solar? Worth reading before you sign anything.
For the technical detail on rebate mechanics and eligibility, ARENA’s published guidance is the primary source, and the network export rules vary by state — check your own distributor’s connection standard before you let anyone size a system for your roof.
— Priya Nair, Solar & Distributed Energy Correspondent
Photo by elaine alex on Unsplash