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Bush
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Joined: 23/11/2020
Location: Australia
Posts: 10

Posted: 07:47pm 14 Sep 2025

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Gday all
I have lived where I am atm since 1997 and have not been connected to grid the entire time,had no idea what power was worth or when it was off.Not completely smooth sailing but have been very happy with my system.
Lead acid battteries originally but now 24v 900amp lithium cells wired by myself.
We have purchased a property in a different location for when we eventually retire and it is grid connected with no solar at all.
My plan if possible and leagal……?
*Get heap of used panels,still can’t fathom how cheap they are .My first 3 64w panels cost me $750 each😲

*set up 48v battery bank,not sure if I’ll make my own or go server rack or similar

*this is where I have no idea,I’d like to have my system run the house but have grid power as either a straight swap(automatically)or as a backup battery charger.From what I’ve read the Victron multi plus units can do this job for me but is it leagal and safe.Can it be set so NO power can get back to the grid.I have no want or need to export to grid.
My current system has a diesel engine that is direct coupled to a special 24v alternator which starts automatically at 25% soc and off at 30%.works fantastic and I’d simply like similar set up at new place but just use grid to do same thing if possible?

Any thoughts or tips greatly appreciated
Cheers Bush

Godoh
Guru

Joined: 26/09/2020
Location: Australia
Posts: 559

Posted: 01:33am 15 Sep 2025

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Hello Bush. I don't know about legal stuff but I do know that if a new system is installed they usually want to have new panels and inverters etc.
By doing it yourself with second hand panels you would save money but you will need a licenced electrician to wire the inverter into the switchboard.
A Hybrid inverter can do what you want, they can run off batteries to run the house and also feed back into the grid.
Or you could have a manual change over switch fitted by an electrician to the switchboard and use any gear you want. It would just mean that when you wanted to run off the grid that you change the switch over manually and then nothing can go back to the grid at all. A double pole changeover switch is what is needed to do that.
I am fully off grid and have been now for over 40 years so don't bother with grid stuff.
But I do know that it is legal to have a changeover switch fitted to the switchboard to use either a generator or off grid system to power the house.
There are many hybrid inverters around that will do what you want.
From what i have seen of Victron gear is it not easy to repair if things go wrong.
Good luck
pete

Bush
Newbie

Joined: 23/11/2020
Location: Australia
Posts: 10

Posted: 07:23am 15 Sep 2025

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Gday Pete
Thanks for the reply
Yes have thought about basic manual change over but it would very much limit the potential of the system.
It would be far more user friendly and get the most out of the system if I could get the system to change over automatically on battery state of charge.Battery drops to 25% system flicks to grid,battery rises to 30% clicks back to battery.
I don’t want to feed power to grid at all,so happy to have change over switch but hopefully be able to automate.
Cheers Bush

Revlac

Guru

Joined: 31/12/2016
Location: Australia
Posts: 1173

Posted: 09:31am 15 Sep 2025

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Gday Bush,

I agree with Pete, I also had a change over switch on the house when we bought the place, it was grid and generator With hi and low power generator inputs 32A and 15A, we used the generator one quite abit when we had grid power that often blacked out, since removing the grid connection and cutting the power pole, the change over switch on some occasions gets used, I wanted to replace the main switch before the inverter, so just plugged the shed power into the gen input on the changeover switch, so no outage of any sort.

I'm sure there are many hybrid inverters that will switch back to grid with a low battery, most of the older design's used battery voltage parameters to trigger, will have to check which inverters use SOC to determine when to switch back to grid and charge....and you would likely need a battery with communication cable to the inverter, so lily a rack mount battery would do this, there should be some types of BMS that would also do this if building your on battery setup.

My other dislike is the ability for a lightning strike to come along the Grid connection and screw the whole thing up.........YES had it happen.

Edit:
It might be better to have a decent quality standalone inverter, away from the grid and a battery charger that is connected to grid and only triggered to charge the battery at your desired set point.

Edited 2025-09-16 10:32 by Revlac

Cheers Aaron
Off The Grid

Bush
Newbie

Joined: 23/11/2020
Location: Australia
Posts: 10

Posted: 03:06am 16 Sep 2025

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Gday Aaron,
Thanks for the suggestions,yes I have thought about a separate battery charger and it could be a good possibility
Cheers Bush

Revlac

Guru

Joined: 31/12/2016
Location: Australia
Posts: 1173

Posted: 12:32pm 17 Sep 2025

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It seems these 48v battery chargers are still expensive and low amperage, there are forklift chargers and I have some old Telecom battery chargers 50A don't see them for sale much anymore.

However there is plenty of "48V Solar Hybrid Inverter Charger Off Grid" most of them are 80A charging or more and also a solar charger built in, those that don't feed to grid might be a cheap option if they cater for charging at user defined SOC, perhaps in a program or they might have a phone APP don't know, if you use your own inverter and one of these as a charger from grid there would be no interruption to your main inverter when charging switches on and off.
I have an old PIP4048HS and it gas a grid or gen input for pass through or battery charging but have never used that for charging, but I think these new types would work almost the same way.
See what you find anyway.

Cheers Aaron
Off The Grid

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