Updated for 2026
Is a solar battery worth it? Here's the actual arithmetic
"It depends" is true and useless. So here's the dependence, spelled out: a battery is worth it when the gap between what you pay for evening electricity and what exporting would have earned you is wide enough, often enough, across the years the battery keeps working. In WA right now, that gap is unusually wide — which is why the question has stopped being rhetorical.
BillWise analyses bills; we don't sell batteries. Every figure below is the published rate or an indicative estimate — installers quote actual prices.
The one number that decides it
2c per kWh off-peak (DEBS)
Under WA's Distributed Energy Buyback Scheme, exports earn 10c during the 3pm–9pm peak — but most of your export happens in the middle of the day, at the off-peak rate.
33.26c per kWh (Synergy A1)
Every kilowatt-hour you buy back in the evening costs the full usage rate — more than ten times the off-peak buyback.
~31c per stored kWh
Give up a couple of cents of export income, avoid a usage charge more than ten times larger. That spread is the battery's entire business case — everything else is multiplication.
(Why is the buyback so low when power is expensive? Because midday WA is drowning in solar — everyone's panels peak together. That's not a scandal; it's the physics of a million rooftops. It's also precisely the market signal that says storage, not more export.)
Four multipliers on that spread
- 1. Your evening usage:
- A battery only earns on kilowatt-hours you actually shift. A household that burns 8–12 kWh between sunset and midnight — air-con, cooking, the usual — has real material to work with. A frugal-evening household doesn't, and no battery chemistry fixes that.
- 2. Your solar surplus:
- The battery charges on excess generation. No surplus (small array, big daytime loads), nothing to store. This is why "battery worth it?" is often secretly "is my solar system big enough?" For an evening-heavy home, a bigger array with the battery often wins. With a battery on a hybrid inverter, the array can go above the usual ratio, up to the inverter maker's limit, and a 5 kW hybrid keeps DEBS.
- 3. The installed price after rebates:
- The WA scheme takes $130 per kWh of usable capacity up to $1,300 off a qualifying system, and the federal certificate discount stacks on top at the current period's rate — a rate that steps down on a published schedule, which quietly worsens the arithmetic for waiting. What batteries cost before and after all that: our solar battery cost guide.
- 4. Cycling, honestly:
- The maths assumes the battery cycles most days, so size it to your evening and overnight use, not to the brochure. A battery far bigger than that can't empty each night, but undersizing is the costlier mistake: evening loads tend to grow, and adding capacity later usually means a second installation.
3–8 year payback
at our two reference Perth profiles, on today's rates and rebates
The cases where the answer is probably no
Independence means saying this part out loud.
- Tiny evening usage:
- If your evenings run lean, the battery has nothing to shift. Spend nothing; enjoy your low bills.
- No solar surplus to store:
- Price a bigger array with the battery, on a hybrid inverter, as one job. In WA, adding to an existing system counts as an alteration, so it pays to plan it once.
- A quote that only works because of the rebate:
- A discount can't rescue an overpriced system. Sanity-check against the cost guide before signing.
- You're buying blackout insurance, not economics:
- Legitimate! But then judge it as insurance — priced against how much outages actually cost you — not as an investment that must "pay back".
The second-order earners
Two things can improve the base arithmetic, with eyes open: Joining a virtual power plant — required for the WA rebate anyway — pays you for grid access to your battery; treat the income as a bonus, not a pillar. And time-of-use plans can widen the effective spread for households whose usage suits them — the calculator models this rather than us generalising here.
It depends on your household, and the inputs are on your bill
A solar battery in WA is worth it more often than it was three years ago — wider spread, stacked rebates, cheaper storage — but it is still a per-household answer, and the inputs are sitting on your last few Synergy bills. Run them. If the numbers work, get quotes with the sizing the calculator suggests. If they don't, you've spent ten minutes to save five figures — the best return on this page.
Related guides
How to size a home battery for Perth: matching capacity to your evening load
Too small a battery leaves you buying grid power at 33c/kWh. Too large and you're paying for storage you never use. Here's how to calculate the right battery size for your household.
Is a home battery worth it in Perth in 2026? The honest numbers
Battery prices have fallen significantly, but so have export rates. Here's a straightforward analysis of home battery ROI in Perth across different tariffs, system configurations, and usage scenarios.
WA Battery Scheme 2026: how to claim your $1,300 battery rebate
The WA Battery Scheme gives eligible Synergy customers up to $1,300 off a home battery. Here's exactly who qualifies, how the application works step by step, and what to do if your claim stalls.
Virtual power plants in Perth: what's available and is it worth it?
Virtual power plants (VPPs) let solar battery owners earn credits by sharing stored energy with the grid. Here's how Synergy Battery Rewards works in Perth in 2026, what it pays and how it ties to the WA rebate.