Home Battery Installation in Altona

A battery does not make energy. It moves it. The saving is the difference between what you would have received for exporting a kilowatt hour, currently under 5 cents, and what you would have paid to import it in the evening peak, currently 30 to 45 cents. That gap is the entire business case.

Which is why a battery makes sense on a house that already has solar and almost never on one that does not. Without a solar system you are buying grid energy off peak and using it at peak, and the margin between two grid tariffs is far too thin to repay $8,000 to $12,000 of hardware inside its service life.

The number that decides battery capacity is how many kilowatt hours you use between roughly 5pm and midnight. For most Altona households that lands between 8kWh and 13kWh of usable capacity, and usable is the word that matters. Nameplate capacity is what is in the cells. Usable is what the battery management system will actually let you take out, and it is always lower.

The federal rebate is calculated on usable kWh at roughly $250 each, which is about 30 percent off, or around $2,500 on a 10kWh battery. Above 14kWh the rebate tapers, so the marginal cost of extra capacity climbs. Combined with the fact that capacity you cannot cycle earns nothing, that taper is a useful natural stopping point for most homes here.

Siting is not a matter of convenience. Batteries have clearance requirements, fire separation rules that rule out some internal walls and positions near exit paths, and temperature limits that matter more than people expect. A unit that spends every summer afternoon at 45 degrees will not deliver the cycle life on its warranty certificate.

In Altona the extra factor is salt. An exposed external wall on the bay side of the suburb is a poor choice for any outdoor electrical enclosure, and it is a worse one for something with cooling vents. Where a garage or an interior-facing wall is available, we use it. Most Altona homes have a garage or carport with a suitable wall, which is one of the quieter advantages of post-war housing stock.

A standard grid-connected battery shuts down during a blackout. That is a safety requirement, not a fault. To keep running you need a backup-capable battery plus a gateway or changeover device, and a backup sub-board carrying the circuits you nominate, usually the fridge, some lights, the internet and a few power points. Running ducted air conditioning off backup is a different and much larger conversation.

Altona also still has homes with ceramic-fuse boards, and a battery cannot be connected to one. Where board work is needed it runs $800 to $3,500 or more. And because a battery inverter is a grid-connected inverter under AS/NZS 4777.2, Powercor needs a new application before it is energised, even where you already have approved solar.