What Size GoodWe Battery Do You Need? (2026 Guide)

The most expensive battery mistake we see isn’t buying the wrong brand. It’s buying the wrong size. Too small and you’re still pulling from the grid at 9pm; too big and you’ve paid for kWh that never get cycled. So how big should your GoodWe battery be? For most Australian homes the sweet spot is 13-26 kWh of usable storage, and GoodWe’s 3.2 kWh module steps make it easier than most ranges to land on your exact number. eHomes installs Fox ESS rather than GoodWe, but the sizing method below works for any brand, and we show the Fox ESS equivalent at the end.

The honest way to size a battery isn’t a formula off the internet. It’s your real evening usage. The number that matters is how much power you burn from sunset to bedtime, because that’s the slice a battery buys back for you instead of the grid. Get that right and the rest follows.

What size GoodWe battery do I need?

Start with your daily usage off a recent bill: the kWh per day figure. Then look at how much of that lands in the evening, because a battery’s job is to cover the hours your solar isn’t producing. Here’s a sensible starting point, matched to the Lynx F G2’s actual capacity steps:

If you sit on the line between two bands, size up rather than down. With GoodWe that’s one 3.2 kWh module, not a whole extra unit. An extra module is cheaper than discovering a year in that the battery runs flat by 8pm and you’re back to buying grid power at 30-50c a kWh. Whoever quotes you should confirm the exact size against your bill.

Size to your evening peak, not your whole day

This is where the supermarket-shelf approach gets people. Your solar already covers the day: panels are producing while the sun’s up, so daytime load mostly comes straight off the roof for free. The battery exists for the other window, roughly 4pm to 9am, when the array is asleep and the grid is most expensive.

So the question isn’t “how much do I use,” it’s “how much do I use after the sun goes down.” On most family homes that evening-and-overnight slice is 12-20 kWh: dinner, dishwasher, a couple of hours of aircon, lights, the morning kettle and showers. Size the battery to swallow that and you wake up having bought almost nothing overnight. It’s also why two houses with the same daily total can need very different batteries. A family home all evening burns far more of its power after dark than a couple who eat out four nights a week.

How GoodWe’s modular sizing works

This is the part that makes sizing forgiving, and it’s GoodWe’s strongest card. The Lynx F G2 is a stack of 3.2 kWh modules on a single tower: from 6.4 kWh up to 28.8 kWh, in steps of one module. Need 16 kWh? That’s a config. 19.2? Also a config. You’re never forced to jump a big fixed unit past your actual number.

Two more layers of headroom sit behind that. Towers can be paralleled (GoodWe supports multiple F G2 stacks on larger systems), so an EV arriving in the driveway doesn’t mean starting again. And for homes that need a wall-mounted low-voltage setup instead, the Lynx Home U builds in 5.4 kWh modules up to 32.4 kWh. Whichever path fits, the matched GoodWe hybrid inverter (EH for single-phase, ET for three-phase homes) should be sized for where you’re headed, not just where you are.

Don’t forget to size the solar to fill it

A battery is only as good as what charges it. There’s no point fitting 19.2 kWh of storage behind a tired 3 kW array that can’t fill it on a short winter day. As a rough rule, you want enough solar to charge the battery and still run the daytime house. For most homes that’s 6.6 kW and up, more if you’re going past 20 kWh of storage or adding an EV.

If you’ve already got solar, that’s usually fine. A good installer designs the battery around what’s on the roof and checks your existing inverter setup before quoting, so there are no surprises. The full rundown on that path is in our guide to adding a battery to existing solar. If you’re starting fresh, size the panels and battery together so they’re matched from day one.

The Fox ESS equivalent: what eHomes installs

eHomes installs Fox ESS batteries only. Using the same method, we size a Fox ESS system to your home from your power bill, with the federal rebate taken off your written quote. Bigger homes and EV households often step up to 28kWh, and Fox ESS stacks to 40 kWh-plus on one setup if you need more later. Our Fox ESS sizing guide walks through it.

Get your size right before you spend

Sizing is the cheapest thing to get right and the most expensive thing to get wrong. The federal Cheaper Home Batteries Program also scales with size: roughly $252 off every usable kWh for the first 14 kWh, then about 60% of that rate to 28 kWh. So a 12.8 kWh GoodWe attracts about $3,226 off and a 19.2 kWh about $4,314 off. For the verdict on the battery itself, read our GoodWe battery review, or see how it compares with Fox ESS, the battery we install, in our GoodWe vs Fox ESS comparison.

Want us to size a Fox ESS battery for your home?

The right size is the one that matches your evening load, not the biggest stack on the shelf. Send your postcode and a recent power bill and we’ll come back with the right Fox ESS size, your rebate applied and an honest payback, so you can compare it with any GoodWe quote. Get a free Fox ESS quote, or read more on our solar battery page.