We install batteries, and we still talk a fair number of people out of them. A battery is a good buy for the right house and a slow one for the wrong house. The difference comes down to two numbers you can find on your own bill.
The maths in plain words
A battery does one main job. It takes solar you would have exported in the afternoon and gives it back to you at night. Feed-in rates in Victoria are now very low, so that exported power earns you close to nothing. The power you buy in the evening costs many times more. The gap between those two prices, multiplied by the units the battery shifts each day, is what you gain.
So a battery can only save what you have spare to store and what you use at night to draw it down. A 10 kWh battery that fills and empties every day does its best work. One that sits half empty all winter, because the panels are only just covering the house, takes far longer to pay back.
Who it suits
- Houses that export a lot of solar because nobody is home in the day
- Households with heavy evening use: cooking, heating, cooling
- People who want chosen circuits to stay on in a blackout
- Homes with a solar system big enough to fill a battery in winter
Who it does not suit
- Houses that already use most of their solar during the day
- Small systems, around 3 kW, with little to spare
- Low overall power users, where there is not much bill to cut
- Anyone planning to move within a few years
For that last group, more panels or shifting hot water to the middle of the day often does more for less money.
Rough costs and payback
A 10 to 13 kWh battery runs from around $9,000 to $13,000 installed, before any incentive. Incentive programs change, so we check what you are eligible for when we quote. As an estimate, payback for a well-suited house is often somewhere around eight to twelve years, against a typical battery warranty of ten. For a poorly suited house it can be longer than the battery will last. That is why we look at your usage before we recommend anything.
Send us a bill and we will tell you which group your house falls into.