Critical load from PV battery

[Pat H]

Hi folks.
I'm having a PV system installed with a 5KW Amasstore GTX5000 Battery.
This comes with a critical load output.
I have the spec sheet but its not clear if this output is active all the time or only engaged when the grid power goes down. I'm assuming its live all the time (unless the battery drops to its cut off voltage)

I'm looking at how best to integrate that into my home circuit?
I am creating a separate ring main for my fridge freezer and separate freezer as well as one lighting circuit that will feed common are lights.
I plan to add a second distribution board in the garage and the have that feed this new ring main and lighting circuit.
I was looking at an automatic change over switch 2P 63A Dual Power Automatic Transfer Switch For Generator Changeover Switch UK | eBay - https://www.ebay.co.uk/itm/203989287846 that would normally be switched to a feed from my main consumer unit (grid power) and upon detecting loss of grid power switch to the Battery critical output.
But is there any need/value in that if the battery is providing power all the time?

Thoughts / advice welcomed.
Thanks

 

[Electro-tech]

What inverter is your PV going to be connecting to? I'm no expert but I would say normally the inverter controls the PV power & battery charging, then you would have management add-ons like Harvi & Eddi etc which divert power around the house to make the most use of available free power. I think the Growatt Hybrid with battery storage provides a connection for a socket etc below.
When you say critical output is this for medical life support.? Regarding the transfer switch, I would like to see if it has been approved for use in the UK. As I doubt it is built to any BS EN Standards.

 

[Pat H]

What inverter is your PV going to be connecting to? I'm no expert but I would say normally the inverter controls the PV power & battery charging, then you would have management add-ons like Harvi & Eddi etc which divert power around the house to make the most use of available free power. I think the Growatt Hybrid with battery storage provides a connection for a socket etc below.
When you say critical output is this for medical life support.? Regarding the transfer switch, I would like to see if it has been approved for use in the UK. As I doubt it is built to any BS EN Standards.

Sorry yes of course it is. Currently the spec is for a Sofar 3K-6K TLM invertor at 6K
No critical as in fridge and freezer. So not critical as such (just the term they use for that specific output.)
Interesting that they are now advertised on this very site

 

[Pat H]

Re UK approval I've not yet found anything that's not industrial plant type size and pricing.
Happy to be pointed to a UK approved domestic solution just found any.
If I have to go with the unit I listed I'll be using a 63A specd unit at max 22A and typically less than 1/2 that. In a metal enclosure.

 

[Electro-tech]

Sorry yes of course it is. Currently the spec is for a Sofar 3K-6K TLM invertor at 6K
No critical as in fridge and freezer. So not critical as such (just the term they use for that specific output.)
Interesting that they are now advertised on this very site

As you are having the PV installation done I suggest you make sure with the installer what you are requesting and they can recommend a transfer switch if needed fit & test the whole installation & issue certification for your own guarantee & piece of mind.

 

[plugsandsparks]

I would view critical as lights and internet access, lol - If the battery system is saying it can power some loads when grid is down then i would expect the transfer switch to be part of the battery system, sometimes it is a separate box where you divert your critical ccts to this box. Beware though if you programme this facility then logically you would not discharge the battery fully under normal conditions as of course you may need some capacity for those critical loads. As batteries tend to discharge over night and be largely flat in the morning it will cost you more (or you will save less) by using this function.

 

[Pat H]

Thanks. Its a bit more complex than that (of course) I'm adding a manual change over switch to my split rail main consumer unit so I can feed an external 3KW generator to that rail (that will feed the "critcal dist board" as well as the rest of the house lights and sockets. the other consumer unit rail will carry the loads too heavy for the genny like hob, oven, washing machine, dryer, immersion.

The plan is if we have a power outage and are at home we wheel the genny out. plug it into an external 16A plug connection.
Then manually switch that consumer rail over to the genny output.

If we aren't around then the Solar battery dos its best to keep the fridge and freezer running (with a 5KW battery that should be a while)

The plan/hope was to have my end in place before the solar people are here as I understand they are only expected to be onsite for a few days. I could wait and show them the proposed setup and get their input but won't have time to then install all that and get their sign off.

 

[richardg]

I’m in the process of installing a solis hybrid inverter with 20Kwh of battery’s, if the inverter has a function for ‘islanding mode’ it will automatically switch the power for you to your critical circuits and automatically stop feeding your main consumer unit. From what I understand That’s why you have to install a earth rod for the inverter for when you suffer a power cut the earth rod becomes your floating neutral. It stops any workers working on the mains infrastructure being shocked by your personal supply. The separate change over switch is more for maintenance - if the inverter breaks down or a problem arises with your pv system you can change over to mains supply for your critical circuits.
Those critical circuits are continually supplied by the inverter.
Has anyone else a more in depth view of the process?

 

[Electro-tech]

I'm no expert but, surely if your inverter is grid-tied & breaks down then you will still have grid supply to your Consumer unit, if the inverter loses grid reference then it will shut down. Maybe a call to Solis or speak to the installer first.

 

[richardg]

I'm no expert but, surely if your inverter is grid-tied & breaks down then you will still have grid supply to your Consumer unit, if the inverter loses grid reference then it will shut down. Maybe a call to Solis or speak to the installer first.

The new hybrid inverters acts as a UPS and switches to battery backup within 20ms and supplies your critical loads. With standard inverters you are right they will shut down when they lose grid reference to prevent the infrastructure workers being possibly shocked

 

[Electro-tech]

The new hybrid inverters acts as a UPS and switches to battery backup within 20ms and supplies your critical loads. With standard inverters you are right they will shut down when they lose grid reference to prevent the infrastructure workers being possibly shocked

I guess you have already searched but maybe this will help although not a Solis inverter.