question

Hi @MarkEss

There's a few things to flag. I think the main thing you're missing is that if you integrate the EVCS into GX/venus os system then it's treated as a normal load, therefore there's no difference between pros/cons of EVCS on ACIN vs ACOUT and the pros/cons of any power load being on ACin or ACOut. It's not treated as a separate thing just a normal load.

Therefore in ESS if the EVCS is integrated it's just seen as an AC load so whichever side you put it on the battery will cover EVCS unless you configure it otherwise (node red) and assuming grid is not down. (That is assuming you have grid meter on ACIN If you don't have an grid meter on ACIN then you may have issues)

The behaviour you're describing/expecting by having EV charger on ACIN is more like what you'd get if you used a system that doesn't communicate with Victron like a Zapi ev charger where you use Ct clamps to monitor/capture excess power being exported which is then used to determine how much to charge the car.

The Victron EV charger has communication with gx device so no need for CT.

The main differences in my view of putting on ACIN vs ACOUT are therefore exactly the same as putting any other load on either side:

EVCS on AC Out:

1. Will stay on during grid outages

2. EVCS charging rate may be limited depending on size of quattro. ie if grid is on but max passthrough of the grid through quattro isn't enough then you may have limited charging speeds on EVCS (unlikely for quattro given they tend to be bigger but if you have a small multiplus this may be a consideration).

ie large AC loads 4000w, Car charger 7000w, quattro needs to be able to supply 11,000w, if Quattro cant passthrough enough grid then EV might be limited.

EVCS on AC In:

1. Not limited by quattro/multiplus max passthrough.

2. Will not work when grid goes down.

I imagine the location of EVCS (ACin or out) is also required/used by victron system to calculate the car charging current in automatic mode correctly.

In terms of setpoint, as it's treated as a normal load it's factored in on AC IN or OUT.

You're 100% correct if you use a zappi ev charge though, that monitors exported power. ie if you make setpoint -1000w the zappi should charge by 1000w by monitoring amount exported to grid via ct.

Again with your last statement, that's true for a zappi ev charger. With a victron charger you'd need to write something like that in node red. At the moment the auto mode uses excess power that would be exported when battery is at 100%/absorption phase, essentially just putting into car rather than exporting. If you want to stop battery at x percentage and put any extra into car you'll need node red. (I'm hoping those types of features get added in firmware updates as using node red is never as clean as a supported feature)

Thanks @matt1309

My Quattro has 100A passthrough capability, so with 7kW EV charger that leaves me 17kW for house (so no issues) Also I don't have a grid-side meter (since all loads are on ACout).

So looks like putting EV charger on the inverter output should be OK.

I now understand EV charger is just considered as a normal load for ESS GX calculations. I can use Node-RED to read home battery SOC and then adjust grid set-point dynamically (say every minute) to make home battery current 0A. The PV export should then go instead to the car (if empty).

I currently do similar to export all PV 4-7pm due to export tarrif.

I hope I understood it, thanks for the explanation.

This should work unless the EV charger actually looks for 100% SOC rather than exported power. I assume it uses exported power rather than monitoring the battery SOC, so if I generate an export it will be picked up regardless of battery SOC

Ah, ok..... maybe dynamically adjust EV charging current to keep home battery current at 0A, if EV charger is in Node-RED.

(and yes using DVCC I've seen only AC PV affected. MPPT still charges battery)

First I need to decide if this charger is the way to go or not