Add small grid-tied battery inverter/charger to existing PV system

joehark

New Member
Joined
Sep 10, 2021
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4
Hello,
I'd like to add a small (~1kW battery inverter/charger 240V ac, single phase, Australia) system to an existing 3kW grid-tied PV system that is working well. I don't want to alter the PV system because "..if it isn't broken, don't fix it."
The reason I'd like a small bettery system is that most of the time when the sun isn't shining, our power usage is below 500W. So an battery inverter would provide the 'first' 500W, then the rest is drawn from the grid. We hardly ever have outages, so this is not really a concern for me.

The only inverters I can find which are low power are Victron (e.g. Multiplus 500VA) (I'm not including ebay / aliexpress) but these don't appear to be able to be safely connected to the house grid (no anti-islanding?) - Or am I missing something when looking at these?.

Has anyone set up a small battery inverter/charger system (can be separate inverter and charger) and are happy to share some suggestions?

Edit: Clarified that I am looking for battery power overnight
 
Last edited:

wattmatters

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Apr 16, 2021
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1,055
I'd like to add a small (~1kW battery inverter/charger 240V ac, single phase, Australia) system to an existing 3kW grid-tied PV system that is working well. I don't want to alter the PV system because "..if it isn't broken, don't fix it."
The reason I'd like a small system is that most of the time, our power usage is below 500W. So an inverter would provide the 'first' 500W, then the rest is drawn from the grid. We hardly ever have outages, so this is not really a concern for me.
Not sure I follow. If you only use 500W, isn't your existing PV system covering much of that already?

Also, not sure what you are really looking for? You want an extra all-in-one PV array / inverter / battery charge controller that is also grid tied?

You'll require local distributor approval to connect to the grid, and all components will need to be on the standards list and more than likely need to be installed by an accredited installer.

Goodwe, Huawei, Delta, ABB all have smaller inverter models. Not 1kW though, most are 2kW+
 

joehark

New Member
Joined
Sep 10, 2021
Messages
4
Are you wanting to run the inverter from battery power overnight?
Yes, I am looking for a low-power battery system to run overnight.

Not sure I follow. If you only use 500W, isn't your existing PV system covering much of that already?

Also, not sure what you are really looking for? You want an extra all-in-one PV array / inverter / battery charge controller that is also grid tied?

You'll require local distributor approval to connect to the grid, and all components will need to be on the standards list and more than likely need to be installed by an accredited installer.

Goodwe, Huawei, Delta, ABB all have smaller inverter models. Not 1kW though, most are 2kW+
I should have been clearer. Not an all-in-one because I will leave the current PV array untouched. I'm looking at what small grid tied battery inverters are available. Of course, approved and installed properly.
Thanks, I'll have a look through the CEC lists.

Has anyone got any experience with / suggestions for 1kW grid tied battery inverters?
 

wattmatters

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Apr 16, 2021
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Not an all-in-one because I will leave the current PV array untouched.
OK, thought you might have been adding an extra array.

I am looking for a low-power battery system to run overnight.
OK.

Silly question time. Why?
We already know it's not for backup:
We hardly ever have outages, so this is not really a concern for me.
I ask because in Australia buying energy from the grid is a LOT cheaper than using a grid tied battery to store daytime energy for discharge at night. It's not particularly environmentally friendly either, especially if you are in QLD, NSW or Victoria. At least, not yet. It's better in South Australia.
 

joehark

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Joined
Sep 10, 2021
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We already know it's not for backup:
Correct, it's not for backup, my aim would be to store excess generated during the day and then power typically small appliances that are left on overnight (e.g fridge, router, server).
I ask because in Australia buying energy from the grid is a LOT cheaper than using a grid tied battery to store daytime energy for discharge at night.
I'm willing to put up with a bit of extra cost to do this in order to reduce the amount of coal-fired power I import at night.
 

wattmatters

Photon Sorcerer
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Apr 16, 2021
Messages
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I'm willing to put up with a bit of extra cost to do this in order to reduce the amount of coal-fired power I import at night.
Your solar PV is already reducing coal fired power supply in the grid. It's reducing coal fired power during the daytime.

By storing some of that daytime solar PV energy and using it at night all you are doing is shifting when the coal fired power is required. Worse, since you lose 10+% of that original PV output in the battery round trip efficiency losses it results in more coal power being required overall.
 

shavermcspud

Solar Addict
Joined
Mar 12, 2020
Messages
309
Hello,
I'd like to add a small (~1kW battery inverter/charger 240V ac, single phase, Australia) system to an existing 3kW grid-tied PV system that is working well. I don't want to alter the PV system because "..if it isn't broken, don't fix it."
The reason I'd like a small bettery system is that most of the time when the sun isn't shining, our power usage is below 500W. So an battery inverter would provide the 'first' 500W, then the rest is drawn from the grid. We hardly ever have outages, so this is not really a concern for me.

The only inverters I can find which are low power are Victron (e.g. Multiplus 500VA) (I'm not including ebay / aliexpress) but these don't appear to be able to be safely connected to the house grid (no anti-islanding?) - Or am I missing something when looking at these?.

Has anyone set up a small battery inverter/charger system (can be separate inverter and charger) and are happy to share some suggestions?

Edit: Clarified that I am looking for battery power overnight
Have a look at the Sofar ME3000SP unit, that does what you want, is fairly cheap and has your country support for anti islanding, Can use LA, Gell or many other lifepo or home made packs.
 

joehark

New Member
Joined
Sep 10, 2021
Messages
4
Have a look at the Sofar ME3000SP unit, that does what you want, is fairly cheap and has your country support for anti islanding, Can use LA, Gell or many other lifepo or home made packs.
Will do, cheers.

I ran a 600w grid tied inverter off batteries for a bit for a couple of hrs after sunset (when we do most of our cooking).
@shavermcspud : Can I ask what inverter you used?
 
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