A home battery is worth buying when it suits the way your household uses electricity, qualifies for the federal discount and can be installed safely in a suitable spot. Before you request quotes, work through eight checks: capacity, power, backup, warranty, discount eligibility, location, monitoring and virtual power plant (VPP) readiness. Each is covered below with the questions to ask, so every quote can be judged on the same terms.

1. Capacity: how much energy you can store

Capacity, measured in kWh, is how much energy the battery holds. The figure that matters is usable capacity, the energy you can actually draw, which can be lower than the nominal figure in the brochure. Size capacity to your evening and overnight usage rather than your total daily usage, because daytime use is often covered directly by solar.

Also check that your solar system produces enough surplus to fill the battery on a typical day. A 6.6 kW system in Sydney produces roughly 24-27 kWh a day on average, less in winter, and part of that is used by the home as it is generated. A large battery paired with a small array may rarely reach full charge.

2. Power: what the battery can run at once

Power, measured in kW, is how much the battery can supply at any moment. A battery with plenty of capacity but modest power output may not run an oven, kettle and air-conditioner together, and the grid fills the gap. Look for the continuous power rating and the short-term peak rating, and check that the inverter does not cap them.

The inverter arrangement matters here. With existing solar, a battery either connects through a new hybrid inverter or is AC-coupled with its own battery inverter, and each approach affects power, efficiency and backup options. The hybrid vs string inverter guide explains the difference.

3. Backup: what happens in a blackout

Not every battery installation provides blackout protection. Some systems shut down with the grid, some back up selected essential circuits, and some can back up most of the home within the limits of the battery and inverter. Ask:

  • Is backup included, and which circuits are covered?
  • How quickly does the system switch over when the grid fails?
  • Can the solar panels keep recharging the battery during a long outage?
  • How much charge is held in reserve for backup, and can I change it?

4. Warranty: the terms behind the years

LFP batteries are commonly warranted for 10 years, but the headline number is only part of the story. Most warranties also limit how much energy the battery can deliver under cover and set a minimum capacity it should retain. Ask for the full warranty document before signing, and read its conditions on installation, temperature and connectivity.

5. Discount eligibility: the federal program

The federal Cheaper Home Batteries Program takes roughly 30% off the installed cost of an eligible home battery, delivered through STCs in a similar way to the solar discount. To qualify:

  • The battery must be installed with solar, either existing or installed at the same time
  • The battery must be on the approved products list
  • The installer must be SAA-accredited

The discount is tiered: approximately $272 per kWh for the first 14 kWh, $163 per kWh from 14 to 28 kWh and $41 per kWh from 28 to 50 kWh. These values step down every 1 January and 1 July to 2030, so confirm current figures on the Clean Energy Regulator's program page before signing. In NSW, the household battery installation incentive has been suspended since 30 June 2025 apart from approved exempt programs, so for most households it no longer stacks with the federal discount. The NSW incentives guide covers what remains available.

Published indicative prices put a 10 kWh battery in Sydney at $8,000-$11,000 after the federal battery discount. Every price is confirmed after a site assessment.

6. Installation location

Where the battery goes affects safety, performance and warranty. The Australian Standard for battery installations rules out certain locations, such as habitable rooms, ceiling spaces, under stairs and near escape routes, and manufacturers add their own temperature and clearance requirements. A good location is typically:

  • Out of direct afternoon sun and protected from rain
  • Well ventilated and within the manufacturer's temperature range
  • Close to the switchboard and inverter, keeping cable runs short
  • Clear of vehicle paths in a garage, or protected from impact

7. Monitoring

A battery app should show charge level, solar production, household consumption, and grid imports and exports. Ask whether consumption monitoring is included, whether the account will be registered in your name and whether you can adjust settings such as backup reserve and charging times yourself. Good monitoring is how you confirm the battery is working the way the quote described.

8. VPP readiness

A virtual power plant lets a provider use part of your battery's stored energy to support the grid, usually in exchange for credits or payments. In NSW, from 1 July 2026, homes and small businesses that connect an existing battery to a VPP can receive a one-off incentive of up to $1,000. Ask whether the battery is compatible with the VPP offers you might consider and how much control you would hand over. Joining is optional, and worth weighing against your own backup needs.

Next steps

Write down your answers to this checklist before any sales conversation, then ask each installer to address all eight points in writing. If you would like the incentives worked out first, the Battery Incentive Assessment in the market ($99, indicative) checks the federal discount and NSW VPP incentive for your property, and Home Battery Installation is listed from $8,490 for a 10 kWh class battery after the federal discount, also indicative and confirmed after a site assessment. For a battery quote based on your own usage and switchboard, request a free assessment from Blue Energy Solar.

Frequently asked questions

Can I add a battery to an older solar system?

Usually, yes. If your existing inverter cannot manage a battery, the battery can be AC-coupled with its own inverter, or the old inverter can be replaced with a hybrid model. The better option depends on the age of the existing inverter, your switchboard and the backup you want. The federal discount can still apply, because the battery is being installed with existing solar.

How long does a home battery installation take?

A straightforward battery installation is commonly completed in a day. Jobs that involve a hybrid inverter swap, a backup sub-board or a switchboard upgrade can take longer, and there may be a wait for network approval beforehand. Ask the installer for the expected timeline from signing to commissioning, including approval steps, so you can plan around the discount step-down dates.

Is it better to buy solar and a battery together?

Buying both together means one design, one installation and one hybrid inverter managing the panels and battery, which can cost less than two separate jobs. Adding a battery later still works well, often through AC coupling, and lets you see your real solar usage first. The federal discount applies either way, but its value steps down over time, which is worth factoring into your timing.