question

Juraj Nikolov avatar image
Juraj Nikolov asked

SOC releay assistent

Hi,

I want to ask, is more detailed documentation available regarding assistants?

I have a network switch and would like to use a relay from GX to control switching depending on the SOC. If the SOC reached 10%, the relay would switch signal eg NC(or NO), using which I would send an impulse to the grid switch, which would disconnect the PV and connect the distribution grid. If the SOC was at 50%, the relay would switch NO (or NC) and send a signal to switch the grid, where it would disconnect me from the grid and connect to the PV.
I'm just missing the documentation so I don't screw something up :)
Basically it is no science… but the documentation is terrible...

Someone help me, please :))


I want to stay off grid as much and as long as possible, even if I have a stable and available distribution grid. I want to use the distribution grid as little as possible and practically only as a backup. From this case I don't use ESS . A little strange design :))


Or are there paid trainings for this? :))


Many thanks for help.

SOCoffgridAssistants
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marekp avatar image marekp commented ·
@Juraj Nikolov

You are right, it is a strange design.

Let see.

When you still getting power from PV but SOC gets below 10%, you want to disconnect PV and get all power from grid.

Why you want to waste power from PV?

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

@MarekP

ok, I'll try to make it a little more specific :)
At the moment I have enough power in PV panels, from March to October it is likely that this power will pull from PVp for my consumption. From October to February, I cannot expect 100% coverage from PVp, maybe 10~20% yes. If it would be controlled as I described, it is highly likely that the PVp will chargeg the batteries when I am disconnected from it. If the batteries reach a certain PVp level(SOC), it switches to operation and disconnects me from the network(grid). So I maximize the profit from solar even in winter, but how much, I don't know.

Does it make rational sense or not ?

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marekp avatar image marekp Juraj Nikolov commented ·
@Juraj Nikolov

Is there a reason why you do not want to use ESS system?

I am also, from March to October, not using any power from grid and augment my PV system with grid power from October to February, but I am not "jumping through hoops" with network switch but simply using ESS assistant.

One can get to the same point using different routs, but why choosing more cumbersome one.

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

@MarekP

If there was no reason, I would use ESS :)


1) ESS does not guarantee you transfers to the network, there will always be transfers, even if small.

2) why should I throw away 1000 euros just to be able to flow into the grid and take power from the grid. For that money, I'd rather buy other components for the victron :)))

3) you don't want the liquidation fine you can get from the distribution, plus disconnection from the distribution as a bonus if you dont want them as a deposit, then ok : ))

This is how I have it galvanically separated, I meet their conditions... and it is safe for distribution technicans.


Thats it


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marekp avatar image marekp Juraj Nikolov commented ·
@Juraj Nikolov

What equipment you have in your system?

From your first post we only know that you have some kind of "network switch", GX device (which one?), and something you call PV.

We do not know.

What battery?

How you get SOC information?

Do you have a Victron inverter/charger?

What kind of PV sytem you have (on-grid inverter, off-grid inverter, hybrid inverter, MPPT charger or PWM charger?)

That information is needed to provide you with any meaningful answer.

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

@MarekP

1x multi2 5kva
3x blue solar mppt 150/45 on each is 2s2p 2kwp in panels this I mean as PV 6kWp (I want to add next two same strings in near future for better charging, 10kWp together)
1x GX cebro
1x SmartShunt500
4x pylontech U3000C

for testing
1x pi2 venusOS 2.66
2x lifepo4 280Ah with JK BMS - I do not have this connected in the system, I'm struggling about the connection and communication of BMS vs. Venus :)


and I run in off-grid mode, not ESS, I already wrote why

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marekp avatar image marekp Juraj Nikolov commented ·

@Juraj Nikolov

If you running it in OFF-grid, you can use grid as it was a generator.

You can start and stop this "generator" by using "generator start stop" assistant.

Your "network switch" (you did not say what it is) can be controlled by this assistant (I hope).

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

This is the network switch, what I have:

https://www.aliexpress.com/item/1005001371428231.html?spm=a2g0o.order_list.0.0.43451802CTEmxi


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marekp avatar image marekp Juraj Nikolov commented ·
@Juraj Nikolov

Three questions:

1. Are you sure that this unit can be controlled by external signal?

2. Are you sure that this unit is certified for your country?

3. Do you have 4p model?

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

@MarekP

Answer at the ->
Three questions:

1. Are you sure that this unit can be controlled by external signal?
NC C NO , not yet tested from me , I hope the relay will be working :D .

2. Are you sure that this unit is certified for your country?
??? why, it is galvanic separatet ? Yes.... I dont care about cert. if it works

3. Do you have 4p model?
No, I got 2P model. If I would need 3F I order new one.

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marekp avatar image marekp Juraj Nikolov commented ·
@Juraj Nikolov

Ad 1. I do not thing those NC C NO terminals are for input. I think those are for output from this switch.

Operation of this switch is either automatic (switches when grid fails) or manual (by hand).

Ad 2. You might not care about certification, but your grid provider will (if they find out you will get disconnected). In many countries the ATS unit is required to have double relay (one after the other for redundancy) in it. This is why Victron put two input relays in MP-II.

Ad 3. OK, I forgot that you have single phase system.

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

It doesn't make sense to me that the relays in this case are like outputs, I hope I'll find time for it today :) and we'll see if it would work as I imagine, but I assume that it does, as it should be possible to connect it to classic switches like MAR : Manual - auto (-off is not an option).

Maybe you are right

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marekp avatar image marekp Juraj Nikolov commented ·

@Juraj Nikolov

2x lifepo4 280Ah with JK BMS - I do not have this connected in the system, I'm struggling about the connection and communication of BMS vs. Venus :)

What voltage are those two LFP 280Ah batteries?

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

@MarekP 48~55.2V

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marekp avatar image marekp Juraj Nikolov commented ·

@Juraj Nikolov

If it is 16s that it cannot be connected to the same bus-bar with Pylontech because Pylontech is 15s.

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

@MarekP

why not :) ???

If i sett JK BMS parameters that the final voltage would be 52~53V (3.25~3.3V per cell for 16pack) and BMS stop charging. And not with 55.2V (3.45 per cell) by 16cells voltage, it will be work but only if is set to 52-53V. It

But I would be lost aproxiemetly 10% of capacity of the 280Ah battery banks, if I calc good... .


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marekp avatar image marekp Juraj Nikolov commented ·

@Juraj Nikolov

Not only top voltage but also bottom voltage is different between 15s and 16s.

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Juraj Nikolov avatar image Juraj Nikolov marekp commented ·

I think bottom voltage is OK by JK BMS thats 3V for 16 pack, because charging to the bussbar should be managed by Pylon. The others battery banks wuold be cahrged as pylon, I think... Discharging the JKs would be not managed by Pylon. And the whole capacity I can mesure with SmartShut...
Pylons botom voltage is 3.2V (2.93V to cut off) top voltage 3.467V.
Maybe I'am wrong...
But if start workin for me the comunication of JK BMS with venus.OS or GX, I will disconet the pylon a sold him : ) If not then I try to sold this 2x 16cell pack with 2x JK BMS JK-B2A24S20P ordered with "CAN" ... withs not working on CAN :D and may be also with not working RS485 :D tomorrow I buy converter USB-RS485 and will see after test...


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Trevor Bird avatar image
Trevor Bird answered ·

Hello @Juraj Nikolov . You could simply use the auto generator start function of the CerboGX to achieve those SOC switching points. The autostart function is perfect for this. A lot of documentation exists for generator autostart.

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Juraj Nikolov avatar image Juraj Nikolov commented ·

Thanks for the direction, I'll give it a try

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Juraj Nikolov avatar image Juraj Nikolov commented ·

@Trevor Bird

This doesn't work for what I need, relays on this my AST doesn't work for my purpose... :(
So I have to find another way:
Ideal solution is if the inverter could turn off if the SOC reaches a certain level of % and turn on again if the SOC reaches the level of %

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marekp avatar image marekp Juraj Nikolov commented ·
@Juraj Nikolov

Try reading about settings of Virtual switch.

There is an option called "dedicated ignore AC input" and there is a setting called "Do not ignore AC input" and

"when state of charge lower than (...)" in (...) you enter the desired SOC.

Maybe this will work for you.

I did not use it myself.

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Related Resources

Additional resources still need to be added for this topic

Victron Offgrid page

VEConfigure Assistants manual