question

mvanninhuys avatar image
mvanninhuys asked

ev charger only grid use

Hello Victron Community,


I am new to the forum and would like to build my own ess system from victron with a multiplus 2 and pylontech batteries.


my question is i have an ev from my employer that i would like it to not use the batteries. I get paid the kw/h price immediately and the car consumes 60kw per day. I can't put that much solar panel on my house ;). therefore want to use the ess system only for my own consumption. is it possible to use a 2nd energy meter for only the charging station, which calculates the difference so that charging only takes place via the grid.


I would like to hear what you think about it, I can't really find a solution on the internet and whether it is possible via ess from victron


Kind regards


Menno van Ninhuijs from the Netherlands


p.s. charging station is an Alfen eve with load balancing via P1 port on the grid meter

cerbo gxESSev charging station
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7 Answers
Jason - UK avatar image
Jason - UK answered ·

@mvanninhuys I have that exact set up. My house runs off my Multiplus ESS on the ACout and I have loads on the AC in side I do not want taking the power from my batteries.

Originally I had a CT sensor on the mains supply to the house between the utility meter and the first distribution panel but when i realised my whole house will work on the ACout minus the EV charger, I moved everything onto the ACout and kept the EV charger on the ACin side of the Multiplus and removed the CT sensor. Have a look on the below link in the photos section where you will find a schematic of my system.

https://vrm.victronenergy.com/installation/171934/share/db6807bb


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Craig Chamberlain avatar image Craig Chamberlain commented ·
@Jason - UK I thought that when the grid is present the AC-In and AC-Out lines are effectively tied together and therefore it's not possible to have the inverter direct battery energy to only non-EV charger loads.

The only way I can think of to achieve @mvanninhuys 's goal is to set up an ESS scheduled charging period for the Multiplus so that it will not deplete the batteries during that period. If you don't actually want the home batteries to charge during this period then you can set an SOC limit to a low value and it will stop charging the home batteries when this level is reached. The key thing though is that the home batteries will not be used during this period which has a downside in that all your other house loads will also be using grid energy at this time.

Maybe there is some other way to achieve what the OP wants but I'm not aware of any.

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Jason - UK avatar image Jason - UK Craig Chamberlain commented ·

@craigc My Multiplus has no idea what power I am consuming from the grid on loads on the AC-in side of the inverter / my AC distribution panel before the Multiplus as it is only measuring the readings from the CT sensor on the AC-in of the Multiplus.

1670258800207.jpeg

Previously I had a CT sensor on the 25mm tails between the utility fuse and the utility meter and power assist turned on and set to 1.0. When this was the case, my Multiplus tried to power both loads on AC-In and also the loads on the AC-Out.

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1670258800207.jpeg (472.3 KiB)
mvanninhuys avatar image mvanninhuys Jason - UK commented ·

hey jason, i just now saw your answer. I have suggested the same scheme later in the message ;) I think this is indeed the best solution

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Craig Chamberlain avatar image Craig Chamberlain Jason - UK commented ·
Right, yeah I see what you're saying. I was thinking at a more "electrical" level whereas you're talking about the "metering" side.


What I mean is that, let's say you have 100% battery charge already and you have a grid load of 8kW of which 7kW is the EV charger and 1kW is the house AC loads. The 7kW is upstream of the MP2 on the AC-In side and the 1kW is downstream on AC-Out1 side but they are all electrically joined by the contactors inside the MP2. So when the MP2 generates that 1kW to balance the house demand, all it really does is provide enough generation to reduce the grid load by the same 1kW. This in turn reduces the power flowing through the power meter inside the MP2 until it reaches equilibrium.


Another way to look at it is that the position of the CT clamp or power meter just changes which loads "trigger" generation by the MP2 and at what level. Once that generation has been triggered, it just gets pushed onto the one combined AC line which is physically connected to the EV and the house loads.

Sorry is this all sounds a bit academic. I'm still learning :)

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mvanninhuys avatar image
mvanninhuys answered ·

thanks for thinking along. I added 2 options. with option 2 the ev charger is already mounted in front of the gridmeter. I think this is the easiest solution. actually there should be a function in the cerbo that if power is requested, this does not come from the battery.option1.jpg

option2.jpg


option1.jpg (95.5 KiB)
option2.jpg (90.4 KiB)
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stefmari avatar image stefmari commented ·

Yes, I would like to believe that option 2 is going to give you charging your EV without discharging your batteries. Let us know how it goes. Best of luck!

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Ben Watts avatar image Ben Watts stefmari commented ·
This is super helpful illustration of two setups I was contemplating


I have a non Victron charger located as with option 2 - ie on the grid side of the Victron energy meter, which is inside my house in the distribution board.


If I bought a zappi, I could easily capture excess solar (at second priority) to the Victron house battery.


My guess is that the Victron Ev charger assumes option 1, i.e that the EV charger consumption flows through the Victron energy meter/CT clamp. So if I wanted to have a Victron charger, I’d need to either supply the charger from inside my house, or somehow shift the energy metering to also capture the EV charger.


Has anyone found any documentation to this point? I feel that to have all Victron would be a nice setup, including the potential option to prioritise between house and car battery charging. But it feels as if the Zappi (or equivalent) is much more likely to just do what I want- capture excess solar and (in winter) do overnight charging.

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Tibor Kocsis avatar image
Tibor Kocsis answered ·

I have the same problem. I have an installation of 3 x Multiplus 1 - 48V 5000 and I have the EV charger connected to AC-in and scheduled charging set in ESS and at the same time my car is charging. Multiplus could have logic in it if I use AC-in at the input, so it would not have to consume energy from batteries in case of unset scheduled charging. Since I have an 11kW charger, it is deadly for 48V batteries. How can it be set or how would it be necessary to connect the EV charger so that when charging is turned on it does not draw energy from the batteries but only from the GRID?

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stefmari avatar image
stefmari answered ·

I am very confident this will going to help however its worth a read,

https://www.victronenergy.com/media/pg/Energy_Meter_ET112/en/installation-and-configuration.html

I am using an ET112 meter installed into the Customer Unit right after 100A switch to meter the whole house consumption. This meter is communicating to Multi2 via usb cable and Multi2 knows how to discharge batteries based on Grid Setpoint and Minimum SOC.

Discharge during day from batteries until Minimum SOC (self consumption as Grid Setpoint set around zero). Charge EV (via charger with schedule) and charge batteries with Multi2 ESS scheduled charge for off-peak.

It this what you would like to do? If yes, you need an ET112 meter connected to Multi2 and integrated into ESS logic with the settings mentioned above.

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eb4gls avatar image
eb4gls answered ·

Hi

I’ve the same system structure with the ev charger in ACIN. i’ am using modbus to deactivate the victron multiplus while ev is charging. In my case I’m charging the car from 01:00 up to 07:00. I‘m using a crontab in my linux to send a command to Cerbo GX at 01:00, this command disable multiplus inverter. At 07:00 another command is sent to enable again multiplus inverter.

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stefmari avatar image stefmari commented ·
this is interesting on modbus . Can you please share the details of the script if possible?
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stefmari avatar image
stefmari answered ·

Hi Its been a while now. I wonder which way you have decided to put the EV charger? It would be nice to see your confirmation and examples how it is actually working ... many of us can learn from it. Thank you in advance.

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markess avatar image
markess answered ·

I'm looking also to add an EV charger (non-Victron) into an ESS system with all house loads on ACout.

I will also put the EV charger on ACout, just like a normal house load, but use a separate ET112 for it and then use Node-RED to stop pylontech charging the car by going on-grid.

So when that ET112 Total Power reported goes above/below a certain amount the ESS state is changed to keep batteries charged/self-consumption appropriately.

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