Is it possible on a multiplus ii, and cerbo gx to turn the grid contactor on and off in the mp, depending on soc in ess mode?
Maybe using node red or a different setting?
Im configured as an ess system purely to feed my exess solar inverter power to the grid once the batteries are full, because if i dont, the generation meter stops counting and ill lose feed in tariff.
So i want to set up my system to turn on grid power in ess once the batteries reach 99%, but then to turn off grid once soc falls to 97% and run off grid until soc reaches 20% .the reason i dont want grid power in under 97% is because my system always seems to draw from the grid at high loads of say 4 or 5 kw (i have a 10kva mp ii) and the whole point of my syatem is to draw as little as possible from the grid.
You could look at the Assistants in VEConfigure.
There you can add Assistants setting stuff based on conditions.
Ignoring AC input based on soc should be what you are looking for.
Think it may work like this:
general flag user → Ignore AC Input:
Relay-Assistant → Set general flag → desired soc:
And another relay assistant to turn it on based on soc.
But you have to try, not sure if this would behave as expected.
Asume you are using external meter?
Multi will draw sudden demand from grid then compensate to max internal settings.
It is “softer” on the inverter and bat.
You could look into running it on CT then it does the opposite.
Will ac ignore option even be available while in ess mode? I havnt looked yet.
Im using the internal ct to monitor power from the grid, i dont have an external meter
Which relay are we talking about, the internal ac in contactor or the aux relay contacts?
You have to try that.
Basically, the relay assistant would toggle the normal relays. BUT it allows to specify the “Set General Flag” option instead.
Then, the assistant “General Flag User” could kick in and set the “Ignore AC Input” according to the General Flag value.
That’s my thought, dunno if that will work.
Ive just checked on ve config, and followed your instructions for using general flag ac1 ignore then set the relay to turn on at 99% soc, but im not sure how to add more comands, as i want to turn the relay off at 97% and then on again at 20%, and i also want to turn it on when loads are higher than 8kw.
Do i just add more relays or more general flags?
You can add multiple assistants.
I assume, the “general flag user” is only required once. It just kicks in, when the other assistants modify that flag.
Then you need:
- set flag → off when soc > 99%
- set fkag → off < 20%
- set flag → on < 98%
Order matters, where it is unclear, if processing is stopped on FIRST match, or if the final match takes effect.
Also you have to wrap your head around the inverted states: Setting the flag to OFF will set “Ignore AC Input” to off - hence the grid is turned on 
(Everything just guessed, just try it, shouldnt break anything)
Ah, i think i go it inverted in my head, so basically ac ignore means “on” for the ralay and ac on means “off” for the relay. I set it the wrong way round as is use general flag, turn relay on when soc is higher than 99%, but because its ac ignore, im basically turning the ac relay off? Am i right? As my configuration which i think i set up inverted is bot working.
So i turned the off’s to on’s and the on’s to off’s, and it appears to be working, the mains light is off and im on 86% soc, so ill wait for tomorrow when the batteries will charge to 99% and see if the grid switches back on.
Fingers crossed - if it works, would be nice if you could post a screenshot of the assitants, so others could easier reproduce that.
It would in theory work but i encountered a big problem. When the inverter is active in “ignore ac in” status, my enphase microinverters stop producing, enen though they are fed into the ac 1 out of the inverter.
However, if the inverter grid input is turned off externally by the grid meter, (without ignore ac in active) the microinverter system quite happily charges the batteries and produces again.
This is strange, any ideas how to resolve this?
So it seems that “ignore ac in” make microinverters stop producing, while if i simply turn the grid off at the breaker, the microinverters carry on producing, this is weird because in both instances they still receive 230v as they are connected parallel to all the loads on ac1 out
Withou AC-IN / Grid the victrons use Frequency-Shifting to control / limit the output of inverters attached to AC-Out. (Frequency then increases upto 53Hz I think)
So, you would need to check the Frequency, to see if that happens, or not.
This is a required “measure” so the system can deal with excess power while beeing offgrid.
Usually the Frequency should be increased (to limit and/or turn off additional inverters) when the battery is not able to take that power anymore.
To define when the frequency should be lowered again (:= turn on PV inverters), you can set the “PV-Restart-Voltage” in the ESS-Assistant. (if you want that to happen earlier than the system would decide)
Thanks for advising about frequency shifting, that never occurred to me. I will check the frequency tomorrow. So if it does turn out to be around 53hz, what settings do i need to change to stop frequency shifting ? I dont want to frequency shift, because once batteries are full, i want to stop ignoring ac in at 99% soc and allow the microinverters to send excess power to the grid.
Node Red will do that with a very simple routine. I use it differently (takes power during free power periods) but the same principle.
Use the Node red:
System Icon (Blue Coloured) and select Battery State Of Charge (%).
then pick;
Switch icon (Yellow Coloured) and configure it to have:
for Property: Msg.Payload
first output select >= then (select number ) then type in 99
click on the + Add at the bottom of the node
configure that line to <= and 97
make sure It defaults to “Checking all Rules”
then pick;
Change icon (Yellow Coloured)
edit the rules to say “Set” msg Payload to the value 3 (don’t forget to set the field to numeric)
then pick another Change icon (node) and configure it to value 2
then pick;
VE Bus System Control Icon (It is the bottom most Blue Coloured node in the pick list) and select Switch Position
Align them and pull a connect line from the input (SOC) into the Switch then a line from the top output of the Switch node to the Change* Node configured to output 3 and the bottom output to the one configured to 2. (this is to set the switch to {3} Onn Grid and {2} Off grid when we have finished the last step.)
Drag a Debug (Green Coloured) icon (Node) and configure it to also output to Node Status.
Drag another (or copy that one) and connect them to the outputs of the change nodes then click Deploy (top right corner of Node Red Window) and observe the outputs.
Observe through a charge cycle to be sure that you are happy then connect the two outputs to the VE Bus System Control Icon (node). Don’t forget to Deploy.
ENJOY!
Omg, thanks so much for taking such time to guide me through all these steps, i teally appreciate it.
Will this configuration allow for my microinverters to still produce when off grid?
It all depends on figuring out why that happens. If it is the multiplus frequency shifting, it will happen, no matter which way is used to cut off the grid. Because it is an essential musst-have security feature for ac-coupled offgrid inverters.
Running your system offgird means that at ALL times pvProduction <= consumable power musst be true. So, if your batteries are full and you only have a regular consumption of 1000 watts, PV needs to be cut down to 1000 watts, through whatever is in the multiplus’ toolbelt.
(BMS driven batteries usually report a redocued maximum charge current way earlier than 100%, so cut down also happens earlier)
Mine usually starts to reduce the charge current limit at around 90% soc:
So, beeing offgrid at time would already cause ac-inverter-throttling, because the power has no where to go.
If there is DC-PV present, the multi will always shutsdown AC-coupled first, keeping the DC-PV alive longer because they are easier to control, so to say.
Try setting ON flag to charge above 95% or less. When at about 95%, in off grid or grid failure mode, the system will start reducing the power coming from solar to protect the batteries. This should solve your micro invertor reducing production problem.
Let us know how you go.
Yes absolutely do this with nodered and no longer with ve-configure assistants.
Two reasons ve-configure assistents are old-fashioned logic and any change in configuration needs reupload of the assistents…and thus restart off the system.
Nodered works on venusos and talks to the inverter system. Change values as you like no restarts needed .