Is your battery saving you money? How to tell from your bills
Verified 17 October 2026
Your bills can show whether you are buying less from the grid than before. On their own they can't show how much of that change the battery caused. This guide shows how to make a fair comparison and what to do with the result.
Compare the same months
Line up a bill from this year with the bill for the same months last year, from before the battery. A summer bill against a winter bill tells you very little.
The numbers to compare
- The days in the bill. A 92 day bill and a 61 day bill aren't comparable. Divide by the days to get a figure per day.
- The kilowatt hours (kWh) you bought from the grid. This is the main one. A battery should bring it down, most of all in the evening.
- The kWh you sent out. It usually falls too, because the battery fills first. The government's solar guide says the lost export income is generally much smaller than the saving on power you no longer buy.
- Your rates and daily supply charge. Retailers change prices during the year. A price rise can hide a real saving, and a price cut can make one look bigger.
What can muddy the result
- A change at home. A new air conditioner, an electric vehicle, a pool or more people at home all change how much you use.
- A different plan. If you switched plans at the same time, you can't tell the battery's effect from the plan's.
- The weather. A hotter or cooler season changes both what your panels make and what you use.
- Time of use. The government's solar guide says the savings from storing your own solar power are greatest on a time-of-use plan, where the stored power covers the dearer hours.
Check it against what you were told
Under the Cheaper Home Batteries Program your installer should have told you the expected payback period. Find that paperwork and see how your bills compare. The government's solar guide also says some batteries may not pay for themselves within their warranty, so treat one year of bills as a first look.
What PowerLens can tell you
PowerLens checks whether your plan is still the right one for your home. It says Stay or Switch, and the Stay answer is free. A bill is enough to price your current plan and flat rate plans. Time-based plans and virtual power plant (VPP) offers need your meter data file (NEM12), which is free to add. PowerLens doesn't measure how well your battery is performing or tell you how to set it. Your installer or your battery app can help with that. No saving is guaranteed.
Start with a recent bill. Or read what to check on your first bill and whether to switch plans after a battery.