How to choose a home battery: capacity, power, backup, warranty and brands

1. What's the difference between usable and nominal capacity?

A battery's usable capacity is what you can actually draw out; the nominal capacity is the headline number it's also sold with. Usable is the number to compare, and it's the figure the federal rebate is based on. Size it to what you use after dark: see what size battery you need. The rebate pays its full rate (about $252 per kWh as of 26 September 2026) on the first 14 kWh, which is why many batteries are sized just under it.

2. How much can the battery run at once?

Power output (kW) decides how many appliances the battery can run at the same time. A battery with 5 kW continuous output will struggle to run a ducted air conditioner, an oven and a kettle together; one with 10 kW or more won't. It matters most for backup and for all-electric homes. Some batteries also list a short peak rating, for motors starting up. Not sure about kW and kWh? Start here.

3. How does the battery connect to your solar?

A battery connects to your solar in one of three ways:

• Built-in inverter (all-in-one). The battery includes a hybrid inverter that runs the panels too. Tidy, and a good fit for new systems or when your old inverter is due for replacement.
• DC battery with a hybrid inverter. The battery plugs into a compatible hybrid inverter, often from the same brand. Check the compatibility list: some batteries only work with one inverter brand.
• AC-coupled. The battery has its own inverter and sits beside your existing solar inverter. Usually the simplest way to add a battery to solar you already have. See adding a battery to existing solar.

4. Is blackout backup included?

A battery doesn't automatically keep the lights on in a blackout. Backup needs the right inverter settings and often extra hardware, such as a gateway or a separate backup circuit board. Ask whether your quote includes it, whether it covers essential circuits (lights, fridge, internet) or the whole home, and how quickly it switches over. Don't compare a quote with backup against one without as if they were the same.

5. What does the battery warranty cover?

Most batteries carry a 10-year warranty, but the details differ:

• Retained capacity: most promise 70% of the original capacity at the end; some promise 60%.
• Throughput or cycle limit: many warranties end early once a set amount of energy has passed through the battery. Heavy use, including a virtual power plant cycling it, can use that up sooner.
• Who stands behind it: an Australian office and a local service network make claims much easier.

Your installer's workmanship warranty is separate, and covers the installation itself.

6. Which battery chemistry is safest?

Almost every home battery sold today uses lithium iron phosphate (LFP), which is a little bulkier than the older nickel manganese cobalt (NMC) type but considered safer. All batteries must be installed to the Australian standard (AS/NZS 5139), which restricts where they can go. For example, not:

• close to windows or vents into living areas (within 600 mm beside or 900 mm below);
• in exits, escape routes, hallways or under stairs;
• in ceiling spaces or wall cavities, or where a car could hit them without protection.

Garage walls and outside walls are common spots. A non-combustible barrier may be needed if a bedroom or living room is on the other side of the wall. Your installer chooses a compliant location; our proposal lets you mark where you'd prefer it.

Check the product safety recalls site before you buy. The Tesla Powerwall 2 was recalled in September 2025 and is no longer on the approved list, so it isn't eligible for the rebate.

7. Can the battery join a virtual power plant?

To get the federal discount, a battery must be able to join a virtual power plant. You don't have to join one. If you do, check which VPPs support your battery, what they pay, any fees, and how much of your battery they can use: VPP cycling counts towards the warranty's throughput limit. See which batteries work with which VPP.

The main brands at a glance

A factual starting point, not a ranking. Models change often; your installer confirms what's current and compatible with your home. Seven batteries in more detail: home batteries compared.

No manufacturer pays to be listed here. Prices vary widely by installer and install, so compare full quotes, not battery prices alone.

A checklist for comparing quotes

• Usable capacity and price per usable kWh, after the rebate
• Continuous power (kW), and peak power if you have big motors or pumps
• How it connects, and whether your current inverter stays
• Backup: included or not, essential circuits or whole home
• Warranty: years, retained capacity, throughput limit, and who handles claims
• On the approved battery list; installer accredited with a battery endorsement
• Where it will be mounted, and whether a barrier or bollard is needed