Deye 8k Grid Load lines

[ezzat]

Hi,
So with my current setup (8kW single phase) I have a conduit from the main switchboard (connecting the whole house, also where the main feed utility comes in) to where the inverter resides.
I am currently running 3x 4mm2 wires for 2x L (Grid and Load) and 1xN and am upgrading to 6mm2 after discovering an issue with one of the wires (due to error by the electrician that pulled the wires).

I am thinking of using just 2x 6mm2 wires connecting to the Grid socket at the inverter side and combining that with the CT cable at the switchboard side where the wire is hooked to both utility and the home switches.

For reference, the utility supply is sporadic, I will have a trip switch disabling it at the main feed point. Will only rely on this to recharge the battery if it's been cloudy for several days which thankfully is about 50 days a year where I am.

My questions:
1- What devices should I have on the switchboard to ensure that the inverter/wiring/home appliances are protected?
2- In this arrangement, if utility is on, the house will be powered by the utility if I'm not mistaken. So if the utility goes out, how instantaneous will the inverter switch over and supply power? I am concerned that such interruptions could damage any of my appliances.

If using just the 2 wires is troublesome, I will revert to the current 3x wire setup but thought of saving the hassle.

Thanks

 

[OffGridForGood]

@ezzat - welcome,
A few questions to help:
Confirm you are talking UK/EU power grid set up, 240 single phase.
can you show a few pictures of the set up for us to see, maybe a wiring diagram,
What make and model is your 8k inverter?
Are you running with or without PV ie, batteries charged by utility? or PV charging batteries?

Most inverters seem to auto switch very fast - 5-20 milliseconds seems typical, letting us know what inverter you have will help with that question.
The more info you can provide, the better the replies will be.

 

[ezzat]

Hi,
Sorry for the long delay.
So this is the current setup (220V/50Hz):

Deye SUN-8K-SG01LP1-EU
Bluesun 700w (6x) connected via 35metres of 6mm2 (15-degree inclination, 195S orientation, location 34.4346° N, 35.8362° E)
Aurora 10.24kWh lithium battery
I also have a 5kW turbine which yet to be installed on the rooftop (wiring completed ).
Also yet to setup are reflective panels to be placed under the panels.

Initially I envisaged the system to run in conjunction with the erratic electricity supply (as well as a diesel generator as backup but have no control on when it's on/off).

I have had the setup in place minus 2 panels (so just 4 panels) for over 2 months but never needed grid supply to recharge the battery (average consumption per day about 8.5kWh including recharging the battery.

I just had the 2 remaining panels installed and don't think I will ever need to rely on the grid or the generator, but would like to keep my options open, particularly for during winter for heating. Both the generator and grid supply are connected via an ATS at the main switchboard of the building so essentially treat both inputs as one.

The problem I have is with the conduits. I do not want to install extra tubing/conduits and therefor am relying on the wall conduits (16mm).

Between the inverter and the switchboard inside the apartment I would have liked to run 3x 6mm2 (2 x L + 1x N) along with 1x2.5mm2 (for distribution to sockets from the switchboard) 1x1.5mm2 equiv (jacketed phone line that goes into the attic where the phone switch resides) but the conduit is way too tight to support 3x6mm2 let alone with the others.

I am considering either:
1- running a pair of 22AWGs for the CT (that will sit in the switchboard) with a pair of 6mm2 for Grid/N (as Deye treats Grid as both an input or output) OR
2- running a 2.5mm2 L wire for the Grid connector on the inverter, and 2x6mm2 for the Load/N. In this instance the feeder will be capped at 20A

The distance between the switchboard and the inverter is 13-15 metres (depending on how cables get routed).

Hope this clarifies

 

[LydMekk]

I have the same inverters.
Your suggested wire size is way too thin.
I would recommend minimum 10mm2.
Both input to the GRID terminal and also from the LOAD to the main fuseboard.

 

[houseofancients]

i use this table as it is our code ( excuse the dutch, use google translate if needed)

Stroomsterkte	Losse kabel tot 25 meter	Losse kabel tot 50 meter	Kabelhaspel tot 50 meter	Kabelhaspel langer dan 50 meter
230V 16A	1,5 mm2	2,5 mm2	2,5 mm2	2,5 mm2
400V 16A	2,5 mm2	4 mm2	4 mm2	4 mm2
400V 32A	4 mm2	6 mm2	6 mm2	6 mm2
400V 63A	10 mm2	16 mm2	16 mm2	16 mm2
400V 125A	25 mm2	35 mm2	50 mm2	50 mm2
400V 250A	95 mm2	95 mm2	120 mm2	150 mm2

 

[ezzat]

Thanks. I doubt I will ever have a draw higher than 20A in any case hence why I don't think 10mm2 will ever be needed.

The 6mm2 I have slightly exceeds the specs of a standard 6mm2 and has a carrying capacity of 43A in open air, 54A in conduit.

My worry isn't with the wire gauge, but rather with the setup. This is the first time I'd be using the CT.

 

[houseofancients]

i use 6 mm for my 3 phase 12k on the ac side.

havent had much good luck with the ct's in my enviroment , so i switched to a eastron meter, which looks better in my din rail box too