I've installed a home battery

[p38arover]

I did some spreadsheet calculations and I think the new 13.4kWh battery connected to my solar panels may pay for itself - eventually. It cost $10,640 to upgrade my solar system to the battery.

If electricity prices continue to rise (despite the gummint's promise of cheaper electrickery), the return on investment may be even better/quicker.

I'll continue to update my spreadsheet to convince myself that I did the right thing. I haven't yet decided whether to change my electricity plan to TOU (Time of Use). Various sites suggest TOU will give a quicker payback.

In July 2022, the supply rate went from 27.6 ¢/kWh to 36.762 ¢/kWh -a 9.162 ¢/kWh or 33.2% increase. (Prices shown include GST.)

In July 2023, the supply rate went from 36.762 ¢/kWh to 46.552 ¢/kWh - a 9.79 ¢/kWh increase, i.e., 26%.

We now get a paltry 5 ¢/kWh for exported power and some suppliers are proposing that we will have to pay them 1.2 ¢/kWh to export between 10am-3pm. When we first installed solar, we were getting 68 ¢/kWh for exported power so our first system (we now have two) paid for itself within 2 years.

What's going to happen this year?


We use a lot of power with the ducted air con. Even the standing power use is around 500 watts. It's amazing how much power is used by multiple computers, three NAS boxes, large TVs, and devices switched off but on standby, etc. Most lights in the house are LEDs. My wife was in hospital last week so I turned off a lot of stuff. That dropped the standing consumption to around 250 watts.

I used to track my solar generation and power consumption on PVOutput but owing to technical reasons, that stopped back in 2019. I've now restarted tracking. This is my PVOutput page: p38arover 6.460kW The graph doesn't take into account what is fed into the battery nor what is drawn from the battery.

I will keep you advised how it goes. The wet weather isn't helping this weekend!

[Arapiles]

Our premium FIT ends this November and after that we'd be lucky to get 5c/kwh - our plan is to increase the number of panels we have, put a battery in and start load-shifting so we're not paying for premium rates in the evening.

[DieselDan]

I've got 12kW solar panels and a 13.5kW battery that I got installed last year.
The leccy provider only gives me 5c/kWh for what I export and charges me higher supply rates between 3pm and 9pm so it's a case of shifting usage and hoping that the battery is fully charged by 3pm so that it covers the high cost period.
It worked really well over summer and the system is still creating significant solar energy at 6pm so between the solar and the battery I never used any peak priced electricity and even made a profit!
In winter, the solar is done and dusted by 4pm, but unless the weather has been really bad, the battery is still fully charged, so it's working out so far.

[DieselDan]

Forgot to add, the standing consumption usually hovers around 0.2 - 0.3kW, which is mostly the fridge, a couple of computers, a few LED lights and the septic pump.
Using the battery app is interesting to watch the different consumption levels of various items as they are turned on!

[p38arover]

I just received my latest electricity bill. For the month, I made a whopping 48 cents from power exported to the grid.

EDIT: Sorry, we made 48 cents, not 37. Updated post

[goingbush]

I've figured out a way to use the 28kwh battery in my E-Landy as a house battery .

Charge on off peak at 8c kwh (midnight to 6am) or for free from 11AM to 2PM then plug in to draw on the battery and feed in to the house at peak evening loads 2PM to mifnight . (peak is 33c on my plan)

I can feed in 1kwh or 3kwh depending which inverter I plug into . Just using second hand solar inverters ,( they don't care if the incoming DC feed is from solar or from a battery ) disadvantage over a proper battery system is I need to manage it manually .

IMG20240617210653.jpg IMG20240617210739.jpg

[V8Ian]

I just received my latest electricity bill. For the month, I made a whopping 48 cents from power exported to the grid.

You could retire on that, Ron.

[Graeme]

How much did you pay for feed from the grid?

[p38arover]

How much did you pay for feed from the grid?

I'm with AGL, their charge is 42.32 c/kWh + GST = 46.552 c/kWh. I'm not on Demand nor TOU rates.

I'm going to seek a better/cheaper rate. AGL don't tell you on their website just what their rates are.

I haven't worked out if it's worth changing to a supplier who gives free power between 11am-3pm. I could use that during winter to charge the solar battery. In summer, that probably won't be necessary as we generate plenty of power then. For example, Oct 2023 - May 2024 we exported 3MWh (before battery installation). For the year Jun 2023 - Jun 2024, we bought in 6MWh after exporting 4.7MWh. I don't know how much of our own power we consumed. The new software that came with the battery installation will give us a better idea of that.

[Graeme]

Thanks Ron. I suppose really I was wondering how much less your grid power is now costing you.
My OE TOU peak rate is 49.7c and my average is 36.4c not including feed-in but the rates would be lower with 5c FIT instead of the 10c FIT on this plan.