Two separate battery and inverters on the same house

new_owner

This might be a daft question. 


Can you have two separate battery and inverter setups in the same house. I mean separate as in two different brands with totally different charge/discharge rates?

I find information that seems to suggest that this is possible with solar inverter and a battery inverter and I am curious whether its also possible with batteries.

If so how would it work?

would they both discharge at around the same rate with a 50/50 ish split or would one be the primary until it was empty and then the other one starts? 

Thank you

1961Nick

They would charge ok from the grid but anything that required the load to be split could be chaotic. The worst case scenario is where one pack decided to discharge into the other pack & when that's finished send it back to the original one.

I know that with pylontechs, if you have 2 or more battery packs you need a hub to sync & control them.

new_owner

I am talking about two separate systems. I realise there would be a danger that if not managed one battery could charge the other. That issue exists with an EV. To avoid this you set the batteries only to charge at a certain time.

I am talking about the load to the house when something is turned on. Where would the power come from battery/inverter 1, battery/inverter 2 or grid.

Solarchaser

Hi its as Nick says.
I've had this with a growatt hybrid inverter and a sofar battery inverter. 
One will respond faster than the other, and cath the load, but then the other inverter will catch up, and now you have export to the grid, first inverter will capture this export and start charging itself, and the second inverter will see this as a load and basically discharge itself charging the first inverter.

I guess the thing to understand is most battery inverters work by reacting to what's happening with mains.
If they see import they start pushing out power to cancel it, and they push out more and more power until they see export, then ramp their output down.
But if 1 inverter is catching the others output then you end up with one discharging to fill the other.

You can get lux acs3600 in parallel configuration meaning they work together and half the load, this is what I have

new_owner

I am not sure this is correct.

Why would the battery charge? Charging on the systems can be set to times not load. 

I cannot see a good reason why this won't work.


Batteries would only charge at off peak times at this point, regardless of the load or the state of charge the batteries are only charging.

I don't export to the grid since there is no solar involved and the battery configuration is not set to export.

If a kettle is drawing 3Kw then inverter 1 might react first. In which case there is no draw to inverter 2. however I don't know if inverter 2 would also kick in and allow power to be drawn. 

Power is pulled not pushed
 

Solarchaser

I've never seen an inverter that will ignore export, but if you find one, it will do what you want.

Inverters tend to change when they see export.

new_owner

Solarchaser said:

I've never seen an inverter that will ignore export, but if you find one, it will do what you want.

Inverters tend to change when they see export.

My Growatt Inverter does not export to the grid?

That would make no sense if it did.

I charge the batteries from the grid and use the power as and when needed. 

I believe most AC inverters have this as an option.

???

94JDH

new_owner said:

I am talking about two separate systems. I realise there would be a danger that if not managed one battery could charge the other. That issue exists with an EV. To avoid this you set the batteries only to charge at a certain time.

I am talking about the load to the house when something is turned on. Where would the power come from battery/inverter 1, battery/inverter 2 or grid.

I have two separate hybrid systems that run the house - depending on the load it will take from either one or both but I haven't experienced discharge to the Grid or one charging the other - maybe I've been fortunate. Winter time they are both set up to charge at the same time period from Octopus Go. The split for me in relation to PV is separate East and West systems.

new_owner

94JDH said:

new_owner said:

I am talking about two separate systems. I realise there would be a danger that if not managed one battery could charge the other. That issue exists with an EV. To avoid this you set the batteries only to charge at a certain time.

I am talking about the load to the house when something is turned on. Where would the power come from battery/inverter 1, battery/inverter 2 or grid.

I have two separate hybrid systems that run the house - depending on the load it will take from either one or both but I haven't experienced discharge to the Grid or one charging the other - maybe I've been fortunate. Winter time they are both set up to charge at the same time period from Octopus Go. The split for me in relation to PV is separate East and West systems.

Thank you for your answer

This is exactly what I am after. Are they completely separate? not in parallel or series?

Do you just set both to charge at 00:30-4:30 and discharge through the day?

Can I ask what brand you have? 

I assume they both run on separate fuses on your CU?

Any issues with your setup. I know you have the solar, which I would not.

94JDH

new_owner said:

94JDH said:

new_owner said:

I am talking about two separate systems. I realise there would be a danger that if not managed one battery could charge the other. That issue exists with an EV. To avoid this you set the batteries only to charge at a certain time.

I am talking about the load to the house when something is turned on. Where would the power come from battery/inverter 1, battery/inverter 2 or grid.

I have two separate hybrid systems that run the house - depending on the load it will take from either one or both but I haven't experienced discharge to the Grid or one charging the other - maybe I've been fortunate. Winter time they are both set up to charge at the same time period from Octopus Go. The split for me in relation to PV is separate East and West systems.

Thank you for your answer

This is exactly what I am after. Are they completely separate? not in parallel or series?

Do you just set both to charge at 00:30-4:30 and discharge through the day?

Can I ask what brand you have? 

I assume they both run on separate fuses on your CU?

Any issues with your setup. I know you have the solar, which I would not.

Yes completely separate - they are mounted in a detached garage each with a 9.5kWh battery.
It's all Givenergy equipment, I've not had any problems with mine, but there is a state of charge bug that's been a problem for a while which apparently will be fixed in a software update so we will see.
Each one has its own EM115 meter in the house to the main supply.
Yes, charging is set for that time period and discharge is set a Eco so it's not force charging only when demand is called for.

new_owner

Thank you very much

Exactly what I was looking for.