Disconnect charger during AC grid

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mika2a asked Oct 13, '20

Disconnect charger during AC grid

Dear everyone,

Firsly my system.

PV system 5600Wc, Multiplus 5000/48, MPPT 150/100 and CCGX. 2 banks of 4 batteries Vitron AGM for a total 48 volts 460 Ah.

During the day I haven't problems, with capacity of batterie, sun power and the power of the multiplus ...

But when the night arrived, with a mean consuption of 600W AC, I can't stay on the batteries. I need at 50% of SOC to connect to grid to recharge batteries. During this process, I charge my batterie and give AC out. A lot of power which is expensive. This power consumpted is more important that a normal comsuption whitou charge (4500w during 3 hours is more important that 600w during 10h).

I would like when the soc is 50% that the multiplus connect to the grid only to forward AC curent to the grid where the AC consuption without charge batterie. When the sun arrived, the MPPT charge the batterie and when the sun power is adapted, the multiplus disconnect to the grid and invert from the batterie to the AC out.

The probleme is my capacity is not enought and if I use only 50% of soc I can't stay the night.

Before I didn't use the 50% of soc but only the minimum batterie voltage at 46 volts. Maybe 46 volts is very too low, is under 50% of the capacity ...

Do you know how I can do this ?

MultiPlus Quattro Inverter Charger

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Answer 1 · 2020-10-15T14:00:16Z

Alexandra answered · Oct 15, 2020 at 02:00 PM

@Mika2a

If you have the ess assistant programmed then this can be done on the ccgx.

You set the minimum SOC to 50% in case grid fails and set optimized with battery life and ess will allow the batteries to drop to 50% and then switch to passthrough then will charge up the batteries again on solar.

https://www.victronenergy.com/live/ess:design-installation-manual#controlling_depth_of_discharge

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Matthias Lange - DE ♦ commented · Oct 15, 2020 at 07:50 PM

If it is only an "old" MultiPlus (not MP-II) and depending on where he/she lives an Anti-Islanding-Relay is needed to use ESS (legally).

But it should also possible to achieve that behavior using the "General flag" and "Charge current control".

I'm not sure if this can also be achieved with the old HUB-1/2/4.

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mika2a Matthias Lange - DE ♦ commented · Nov 01, 2020 at 05:19 PM

Dear Matthias,

So after installation and settings, in the ESS mode, I notice that the system still keeps a connection to the grid despite a 92% SOC and an AC load of 500w and a PV production of 650w. Weird .... I don't have battery charge priority though!

I did not keep the ESS for a long time due to this AC connexion ! However there was another assistant: HUB 2 which seemed fairer to me. So I installed it and waited to see its behavior.

I didn't see in the general flag option, somes options allowing to switch the charger mode ! only AC input.

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mika2a commented · Nov 01, 2020 at 05:30 PM

Dear Alexandra,

As I said to Matthias in the post below, after installation and settings, in the ESS mode, I notice that the system still keeps a connection to the grid despite a 92% SOC and an AC load of 500w and a PV production of 650w. Weird .... I don't have battery charge priority though!

I can keep in production and consumption without the network. Certainly I only use my batteries at night but during the day the grid connection is not justified with its days !

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vrm.gif (22.9 KiB)

Answer 2 · 2020-10-15T21:40:55Z

mika2a answered · Oct 15, 2020 at 09:40 PM

Dear Akexandra, Thanks for your answer ...

But I didn't finf in my CCGX display the ESS setting ! is an asistant to be uploaded in the CCGX system ?

I had used only the VE config interface (mk3) to connect to my Multiplus for connecting to the grid when the SOC is under 50% or 49 volts.

I need to read the ESS design and installation corectly to understand. But is available in French for more facilities ?

Dear Matthias, my multiplus is not an MP-II.... and I don't understand your idea..

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Alexandra ♦ commented · Oct 16, 2020 at 06:04 PM

@Mika2a

If you do not see ESS in the GX menu anywhere, then ESS is not programmed in on your system. It is an assistant programmed in the assistant tab.

https://www.victronenergy.com/live/assistants:ignore_ac_input_using_the_generator_assistant

The link above is also an option depending on the firmware you are running. How old is your multiplus, the article does mention basic requirements and is simpler than ESS.

Not sure what part of the world you are in but if it is Europe and some others then Matthias is right to run ess you will need the newer unit Muli II, that has extra built in safety features. Where I am in Africa it is not a requirement though, so knowing local law is important.

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mika2a Alexandra ♦ commented · Oct 16, 2020 at 06:27 PM

Thanks !! I have the ESS menu in my CCGX but is empty. I need to had an assistant via the MK3 interface in my multi. If I understand correctly the manual.

I don't know if the ESS system is relevant for my installation and for that I want.

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Alexandra ♦ mika2a commented · Oct 16, 2020 at 07:41 PM

@Mika2a

You understand correctly.

With ess you are always grid connected. But you are able to interact through the GX menu and change setting as you want to.

With ac ignore it will disconnect and reconnect as you set it to do so. This is set and you can only change the program by using the mk3 again.

If you don't want to charge from grid at all you can disable the charger on the charger tab. (But remember to re enable you would need to program that again as well).

Once you have decided how you want to proceed the choice is simple.on the program side.

I have attached what an ess system looks like from grid useage and SOC control.

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screenshot-20201016-213641.jpg (185.9 KiB)

screenshot-20201016-213842.jpg (121.2 KiB)

Answer 3 · 2020-10-16T11:43:53Z

JohnC answered · Oct 16, 2020 at 11:43 AM

Bonjour @Mika2a

I wouldn't worry about ESS unless you have a specific need for it (like exporting power to the grid).

You could try a simple fix/workaround.. With your MK3, set your Multi charge settings to a very low V, like (say) 52V for both Absorb and Float. Or set your Charge Current to (say) 1Amp. Either way it will still charge, but insignificantly.

Voltage is useless to work from if you have current moving either into or out of your batteries. And your SOC may not be correct either. Note your 48V/460Ah batteries are nominally 22kWh capacity, your '600W for 10hrs' just 6kWh. With inefficiencies, let's call your batteries 20kWh, so that's just a 30% drawdown (70% SOC). That's of course if you started with full batts.. relevant?

You don't say from where you derive your SOC, but your system is large enough to justify a real-deal BMV or Smartshunt. Set up properly it could totally change the way you run your installation.

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mika2a commented · Oct 16, 2020 at 06:36 PM

Dear John,

My SOC is derive from the multiplus 48/5000. Normaly when the MPPT is in floating mode, the SOC great to 100%. Is necessary to add a BMV or a Smartshunt if the multiplus make the job ?

I export no current to the grid. But I would like to minimize my connection to it.

If I understand the battery life. I can use only 50% of the capacity. 48v/460Ah = 22 kWh / 2 = 11 kWh. At this time the weather is not too bad but for today for example my SOC is 78% at 18h. 75% (50.2volts) at 20h.

With 500w of consumption during 12h, tomorrow morning my voltage is under 49 volts so I need a connection to grid.

But I don't want to charge at 100% my batterie when the soc is under 50% because too much of consuption. I want just to charge a little bit to wait the sun back for charging.

I see my voltage which not be under 49 volts, approximately 50% SOC and capacity.

Before that I change my 4 x AGM battery destroyed by 8 new ( I switch on the equalization mode ! ) I used the batteries to 46 volts ! Yes it's great because I had more longer power but the technician tel me is not good for the batteries life.

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mika2a mika2a commented · Nov 01, 2020 at 08:21 AM

Dear John,

Could you explain me to try a simple fix/workaround... ?

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Answer 4 · 2020-11-01T09:38:39Z

Dear Alexandra, Dear John, dear Matthias,

Thank you for all your answers.

First, I updated my multiplus firmware to 2624476 to access the ESS assistant.

But in all the assistants, I couldn't find what I wanted to do! or else I did not succeed !!

One problem I have solved is that my multiplus does not have a VDE protocol. Moreover I don't want to inject into the grid.

John was taking about simple fix/workaround... ?

I would like when the batteries voltage is under 49 v or a SOC under 50% to connect my consumption directly to the grid without to charge batteries in the same time. And when the PV increase the battery voltage to a value up to 50v, the multiplus switch to inverter mode !

Actually In my system, when the multiplus produce energy to my house's consumption and when the voltage is under 49v, he switch to the grid for the house's consumption AND the batteries's charge !

It is a lot of consumption which was not necessary !!

Secondly in other program's, I would like to be able to configure the system so that when the PV is not enough to charge the batteries up to 50v or more (due to bad weather !!) to be able to reconnect the multiplus in charger mode.

Where, the connection to the grid is fully justified

Of course, this configuration should not be at the expense of destruction of batteries or a limited life.

If you want access to my VRM portail or CCGX console to see or to change my parameters do not hesitate to ask me !

Thanks a lot
Michaël

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