r/Aus_RenewableEnergy

I’ve been a renewable enthusiast for years and have been lobbying for this stuff for a long time — but when I actually went to install solar on my own home, I still ended up completely confused and installing something far bigger than I needed. Then I went looking into batteries and got even more confused.

So this is my attempt to help the cause, use everything I have learned, and strip it all back.

No signup.
No quotes.
No sales pitch.

Just rough numbers to help people think clearly before spending thousands.

👉 https://worthitcalculator.com.au

I’d really love your feedback — I’m trying to keep everything as simple and practical as possible.

Is this useful?
Is it clear?
What’s missing?

Hi All,

So had a 41kw battery installed a couple of days ago, however im reading now that a controlled load hot water system isn't natively wired to use battery power?

After watching the usage of my battery, I doubt it is coming out of it, (the draw is too low with no noticeable spikes I can't explain)

Don't suppose this is something I can change a setting or toggle for? or will I need to get a sparky out to rewire the thing.?

Hi all, need ideas or examples (Brisbane). We already have a grid-tied system that's 14 years old but works perfectly. It has a very generous FIT that you wouldn't get today (which we LOSE if we make changes).

There are hundreds of solar panels being removed these days so they're available cheap or free AND I've sometimes seen hybrid inverters in FB Marketplace for $100 or so. The issue is they need batteries, typically 48 volt which cost thousands 😕

If it weren't for that issue I'd have put up some second hand panels, attached the inverter/battery and used it ONLY during the middle of the day to charge an electric car by now. What's holding me back from getting an EV is that we depend on exporting electricity during the day to give us a small tax free income every 3 months in retirement so this has to be quite separate from the above.

24 volt batteries are much cheaper and we only need them to smooth out the fluctuations in mid day production, not as storage for (overnight) charging. So can anyone suggest an economical way around this? The ideal would be someone upgrading a small completely off grid system and getting rid of everything even if the battery is old and tired. I just can't afford to spend thousands of dollars on a new lithium 48 volt battery.

Any polite alternative suggestions welcome thanks 🙏

Hi folks. I signed up for a solar panel+battery+inverter install which was due in March but was continually shifted until they finally stated they were cancelling the install right at the end of April. I had paid a 5% deposit which remains redeemable, and was offered a lesser deal or my deposit back.

I’m sure there are others in this boat. Perhaps r/auslegal is a better place to ask, but is there anyone with experience in whether the contracts should be honoured? Thankyou!

Sanity check needed:

So I recently got a 30kw Battery, 10kw Hybrid inverter (updated from std inverter) and already had 13.3kw panels on the roof (single phase).

I didn't change energy providers or set up exporting etc when we got the battery because I wanted to get a good understanding of what our use is to inform any tweaks to the timer items (pool pump and hot water etc) and to have to do a comparison across providers. Side note there is now some tiny feed in over night - like the reverse of the grid handshake.

Each provider has slightly different tariff set ups (peak/shoulder/off peak/ free hours) etc and because I could get my data in 30min increments via CSV download from Origin I was able to apply all those variables to the data when looking at it since install.

Below is my calcs based on no forced discharging or charging of Battery and the only feed is excess Solar once Battery is full (or those random tiny feed in through the night). Grid usage is the handshakes or where PV production drops suddenly and a load spike happens during the day (it's working out to be an average of 456w per day).

Period: 33 Days

Total Grid Consumption: 15.048 kWh (456 watts per day)

Total Excess Solar Feed In: 1000.51 kWh

Current Standard Origin Solar Boost plan I'm on:

Access Charge $1.42868 per day x 33 = $47.15

Single Tariff Consumption $0.35244 per kWh = $5.30

less FIT first 8kWh per day (8*33 = 264kWh) $0.10 per kWh = $26.40

less FIT rest of kWh $0.03 per kWh (736.506kwH) = $22.09518

Total Bill for period = $3.95

Origin Battery Saver:

Access Charge $1.4685 per day x 33 = $48.46

Origin Peak Consumption (4pm-9pm = 1.584kWh) = $0.68

Origin Off Peak Consumption (9pm-4pm = 13.464kWh) = $4.24

less Peak FIT (4pm-9pm = 30.802kWh) $0.18 per kWh = $5.54

less Off Peak FIT (9pm-4pm = 969.704kWh) $0.05 per kWh = $48.49

Total Bill for period = -$0.65 (Credit)

Note: Need no battery discharge to break even or be in credit

GloBird Zero Hero

Access Charge $1.474 per day x 33 = $48.64

GloBird Peak Consumption (4pm-11pm = 1.741kWh) = $0.82

GloBird Off Shoulder Consumption (11pm - 11am and 2pm-4pm = 12.188kWh) = $4.02

GloBird Free Consumption (11am-2pm = 1.119kWH) = $0

less standard FIT (4pm-11pm = 32.29kWh) $0.05 per kWh = $1.61

less Peak FIT Bonus (6pm-9pm = 2.441kWh) $0.10 per kWh = $0.24

less Zero Hero Bonus of $1 a day with <.03kWh/hr (6pm-9pm) 33 = $33

Total Bill for period = $18.63

Note: Would need to discharge 3.76kWh per day between 6-9pm to break even (18.63/0.15/33)

*The extra 10c per kWh for 6pm-9pm: 15 cents/kWh applies to the first 15 kWh of exports between 6pm-9pm (Local Time) everyday, and is inclusive of any other Feed-in tariff as applicable in Energy Plan. Inclusive Feed In Tariff is 5c Rebate per kWh exported GloBird feed-in between 4pm and 11pm (incl. GST if any).

Now this is specific to me and our house usage and set up etc, so am not trying to say which is the better plan for everyone, but asking for a sanity check... am I missing anything? At the moment I feel that the Origin Battery Saver is the better option for me based on my specific data as I don't have to charge the battery from the grid during the free hours and I'm in credit (small) without having to discharge anything from my battery.

Some additional context - I'm in SEQ where my battery is full by 10am and if it's rainy it's about 12pm that the battery is full - ANZAC day was the exception and it finally was full at 4pm.

I have the ideal roof - facing north - up high, no shading at all and we've had the panels for 3 years and they produce about 2MWh each month in Summer (December 2025 was 2.2MWh with 1.4MWh feed in - on average 45.16kWH per day) and the lowest was June with 1.3MWh (with 791.3 kWh fee in - on average 26.37kwH per day).

I have spike hours for doing a forced charge if needed at the moment (6 hours in the bank) but so far haven't needed to do that and I know they we won't earn many more as our historical usage will soon include time with the battery.

We don't have an EV ... yet.

Not sure what will be the plans for Origin when the 1 July solar sharer changes are required (I know it's a max 24kwh charge in the three hours).

Currently feeding in on average over the 33 days 30kWh to the grid between 10am-4pm after battery is charged.

So what have I missed? Is it just the case of in case I need to charge my battery from 11am-2pm that GloBird is the better option (?) because that need isn't there at the moment.

NOTE: I did the calcs for OVO 3 for free and AGL Battery saver but they were worse than the three plans based on my data so I've ruled them out for now (Ovo was coming out at a bill for $33.07 and AGL was at $26.49).