Deye 6kw single phase inverter, CT coil/generator input on line in. (off-grid)

[Ecobuilders]

Greetings to all the solar community.

I have recently installed a Deye SUN-6K-SG03LP1-EU inverter in our off-grid set up and am really very happy with it. So far it is performing so much better than my old Axpert VMIII that is now on a backup system running several freezers.

I have a couple of questions that, despite searching far and wide, I cannot resolve.

1. I have connected my inverter generator to the line in (mains) because I want to use the generator port for the dump load facility it provides at a later date. Can anyone clarify where, if at all I should place the CT coil? As I see it the coil appears to be required to stop the flow of power back to the generator and causing damage. Of course I have not yet run the generator, given the performance of the twin MPPTs that are converting available light better than the VMIII, I have not yet needed to. Of course I probably would have for at least a few days in winter.
would it be feasible to have the CT coil at the point where generator wiring enters the inverter or does it need to be further away? As a side note, I did read somewhere that the CT coil may be better placed on the supply side, again suggesting it monitors output not input!! I don't see how this could possibly protect the generator! Confusion abounds.

2. Despite several attempts at making up a BMS communication cable to enable the inverter to better calculate SOC and more importantly the state of individual cells etc, nothing seems to work. The batteries are Pylon tech US5000 (master) and 4 x 2000 Plus that were on the previous VMIII. I have stuck with RS485 as the protocol but apparently the inverter socket can accept RS485 or CanBUS. Can anyone confirm what my RJ45 wiring should be. Currently I am using just 3 wires 6,7 & 8 being RS485 ground, A & B.

The manual that comes with this inverter has a swamp load of information and several schematics of parallel connections etc but nowhere does it give a single example of an off-grid system, I find this strange.

Any assistance would be greatly appreciated.

 

[timselectric]

When connecting a generator to the grid port. You have to change the grid port for generator input. (There is a setting for this)
No CT's required.

I can't help with closed loop communication, I don't use it.

 

[LydMekk]

The CT must be placed on the LINE + cable. Measure to be sure it isn't the neutral f.ex.
Don't trust the colors...
Usually the plastic arrow must point to the inverter (along the cable).
This is mentioned in the standard Deye manual which came with the inverter.

 

[timselectric]

The CT must be placed on the LINE + cable. Measure to be sure it isn't the neutral f.ex.
Don't trust the colors...
Usually the plastic arrow must point to the inverter (along the cable).
This is mentioned in the standard Deye manual which came with the inverter.

You don't need a CT on a generator input.

 

[Ecobuilders]

When connecting a generator to the grid port. You have to change the grid port for generator input. (There is a setting for this)
No CT's required.

I can't help with closed loop communication, I don't use it.

Thank you. I've seen the tick box for the generator on line in and have done this.

 

[Ecobuilders]

The CT must be placed on the LINE + cable. Measure to be sure it isn't the neutral f.ex.
Don't trust the colors...
Usually the plastic arrow must point to the inverter (along the cable).
This is mentioned in the standard Deye manual which came with the inverter.

Thank you, I noted this but from memory it didn't apply to the generator input as this wasn't mentioned.

 

[Ecobuilders]

You don't need a CT on a generator input.

Presumably this is an update to your previous reply to put the CT on the +ive coming form the generator? So do I need to check any of the boxes such as zero export etc? How else can I ensure that the inverter does not feed back to the generator please? A replacement generator is more expensive than a replacement inverter so I'm keen not to damage it.

 

[timselectric]

Presumably this is an update to your previous reply to put the CT on the +ive coming form the generator?

Not my reply.

So do I need to check any of the boxes such as zero export etc?

The "GEN connected to Grid input" setting, takes care of it.

 

[Ecobuilders]

To clarify, the BMS communication cable issue is temporarily replaced with manual settings based on voltage. I erred on the side of caution with 3.45v per cell x 15 = 51.75v maximum. The batteries were overcharging so this seems a safer option. The batteries discharge every day, usually down to about 48.5v so I'm hoping this won't build up any sort of memory affect for partial charging.

I'm not aware of any benefits of CanBUS over RS485 but stand to be corrected. Seeing as both inverter and batteries seems to be capable of either does anyone have suggestions for both a solution and a preference?

Thanks in advance.

 

[Ecobuilders]

Not my reply.

The "GEN connected to Grid input" setting, takes care of it.

Apologies timselectric, I'm an old codger and easily confused! Thank you for your additional input. Very much appreciated.
It seems to me that manuals have a long way to go, when I have more time I will post something to summarise my questions and the answers gleaned in the hope that others will not need to ask them.