Why batteries have started making sense
For years the answer on batteries was "wait". Two things changed that. Feed-in tariffs fell to the point where exporting is worth very little, which widened the gap between what you are paid for a kilowatt-hour and what you pay for one. And the federal battery discount introduced in mid-2025 took a substantial share off the installed cost.
The gap between the export rate and the evening retail rate is the entire business case for a battery. The wider it gets, the faster storage pays back.
Sizing: bigger is not better
The right size is roughly the amount of energy you use between sunset and sunrise, not your total daily consumption. Sizing beyond that means paying for capacity that sits unused most nights.
For a typical Melbourne household, evening and overnight consumption is often somewhere between 8 and 15 kWh. Homes with electric hot water, an EV, or ducted heating running overnight sit well above that. The way to know is to look at your interval data rather than guess.
It also matters that most batteries should not be run to empty. Usable capacity is lower than nameplate capacity, and the quote should state which figure it is using.
Backup is a separate decision
Not every battery gives you power in a blackout, and the ones that do need it designed in. Backup requires a changeover mechanism and a dedicated essential-services circuit — typically lights, fridge, internet and a few power points, not the whole house and rarely the air conditioning.
It adds cost and switchboard work. If you are on a reliable part of the network and outages are rare, it may not be worth it. If you are in Warrandyte or on the semi-rural fringe where storm outages are a regular event, it often is.
VPPs and what you are agreeing to
Virtual power plant programs pay you to let a retailer discharge your battery into the grid at peak times. The payments are real, but so is the trade-off: you have less control over your own stored energy, and there may be minimum contract terms.
Note that the federal battery discount requires the battery to be VPP-capable — but capable is not the same as enrolled. You can take the discount without joining a VPP.
What’s included
- Assessment of your evening and overnight consumption from interval data
- Battery and inverter selection with usable capacity stated, not just nameplate
- Backup circuit design where you want blackout protection
- Switchboard modifications where required
- Federal battery discount applied to your quoted price
- Distributor approval and commissioning
- App setup and a walkthrough of how to read it
Common questions
Can I add a battery to my existing solar?
Usually yes. Whether it is straightforward depends on your existing inverter — an AC-coupled battery works alongside almost any system, while a DC-coupled option may need a hybrid inverter. See our page on adding a battery to existing solar.
How long do batteries last?
Most lithium batteries carry a ten-year warranty with a retained-capacity guarantee, commonly around 70% at end of term. Real-world life depends on cycling depth and temperature. A battery in a hot west-facing garage will not age as well as one in a shaded, ventilated spot.
Is a battery safe to install inside?
Installation is governed by AS/NZS 5139, which sets out where batteries can and cannot be placed — including restrictions near habitable rooms and exits. A garage or external wall is the usual answer. Any installer who is vague about this standard is a warning sign.
Will a battery take me off the grid?
Not realistically in suburban Melbourne. Going genuinely off-grid needs several times the storage and generation, plus a generator for winter. Staying connected is cheaper and more reliable.