Posted by So, it’s now been three months since I’ve had a home battery installed (a FranklinWH 13.6 kWh battery) plus some extra solar … and I was curious to see what impact it has had on electricy usage and costs …
My gut feel (based on monitoring the app regularly) was that it has been doing really well as even with needing to charge my Byd Atto 3 and despite us being a very heavy usage household, as we head into summer we are consuming practically no electricity from the grid, and looking at my total energy consumption from the grid over the last few years, you can clearly see that my daily usage over the last three months has dropped, particularly in December.
I should also note that I think most of the December consumption is attributable to my using Aurora’s free ‘power hours’ to charge the EV and the battery (just because I could).
Looking at my solar generation, despite the extra 3 kw’s of solar on the roof, there was a drop in the export of solar power in November, but usage stayed pretty steady in the other two months.
This reflects a change in my charging habits (most noticably in December) where I am now leaving my car plugged in on Eco++ mode on the days I am working from home so that any surplus solar first charges the home battery, then goes into the EV, then goes to the grid.
This has resulted in my only having to do one small charge of the EV (off the grid) in the last six weeks. So free car travel!
From a financial perspective, my December 2025 bill was a sum total of $12.86 (compared to $104.65 the previous year), which I obvioulsy liked, and comparing the three months (Oct, Nov and Dec) in 2024 to those in 2025, my overall bill has decreased by 46% (but only from a total of $366 down to $167) … so a $198 saving, year on year, over three months, plus as noted above – I’m travelling about 150 to 200kms a week in my car and it’s not costing me anything.
And from an environmental / community perspective, I am really happy that I have virtually removed all of my peak electricity consumption (down by 80% and most of that 20% was me using free ‘power hours’) so that does my small part to reducing the potential need to import carbon intensive electricity from the mainland and also lowers the overall peak demand on the network costs which are a big contributor to total electricity costs for everyone else.
In terms of learning, There’s part of me that wishes I had gone for a slightly larger battery, say about 20 kWH as I did notice in the early period after having the battery installed that with the heat pump running for a few hours in the evening, that the battery needed to be topped up to get through the morning peak. Unfortunately you can only add Frankling batteries in 13.6kWh sizes and I’m not sure it would be worth the cost of adding a second battery (I suspect the net cost would be around $8000).
I’ll try and come back and see how it does in another 3 or 6 months.