Is It Time To Get A Battery?
Originally posted in 2023 but revised following the announcement of Federal Government Battery rebates in 2025.
I got my Electricity Bill the other day which set me wondering if I should invest in a battery for our house.
Our Situation
We live in a retirement unit which is reasonably compact.
As a result our 3.25 kW of Solar Panels takes up most of the available roof space.
The advantage of having a small house is that although we are all electric our daily usage is quite small.
The below graph shows our daily usage and solar export.
From the figures above it would appear that with a battery we should be able to store, and then use overnight 3kw of power almost every day, or an average of say 5kWh.
Power Company Rates
Our current rates from Red Energy are:
$0.25718/kWh Consumption Charge
$0.045/kWh Feed in Tariff
Annual Savings
The annual savings by installing a battery will be:
Consumption Charge minus the feed in Feed In Tariff multiplied by 5kWh multiplied by 365.
$(0.25718 – 0.045) x 5 x 365 = $387.22/year
NB There will be some efficiency loss in the battery but this may be compensated by the battery partially discharging and being recharged during summer days.
Conclusions
Recent industry figures (May 2025) indicate the installed cost of batteries is $1,000 to $1,200 per kW.h
This gives a full cost for a 5kWh of $5,000 to $6,000.
With the potential election rebates announced in 2025 these prices could drop down to the $2,500 – $3,000 amount
With a battery payback at $380/year is going to be around eight years, by which time the battery will have gone through over 3,000 charging cycles.
It is starting to look as though batteries are starting to be more cost effective.