Hello Victron Community,
i need some help to get my VRM in a bit special system right.
At first, i am an electrical engineer working on PV Systems up to 1 MW in Germany. The system i am talking about is mine and i have build it from scratch.
The main system is a Multiplus 2 5000, Cerbo GX, Smartshunt 500 A, Bluesolar 150/30 and Smartsolar450/100. Victron EM540 for Grid Connection and EM540 for PV Inverter. Some LFP cells.
From work i have old SMA Sunny Boy 2500, 3000, 3800, 2100 TL, … Because they are so old they dont have the VDE AR-N 4105 Grid Guard. Only the old 0126. So i dont want them to be connected to the grid or feed back. That is why i have ESS off and use the Multiplus like in a car or boat. If the Multiplus is in Overload or batteries are empty, the Cerbo GX is disconnecting the PV Inverters with a big relais. For that i am using the generator function on the Cerbo GX and say that it is not allowed to have grid and generator at the same time.
Now in the winter i need some energy from the grid. Until now it was when batteries are empty, then it was connecting to the grid and PV Inverters where offline. This is configured in the Multiplus. I want it to work even if the communication to the Cerbo GX is broken. Two problems with this solution: It is bad when the batteries are empty the whole winter in an case of grid failure. And every time the Multiplus is charging from grid, the PV Inverters are not working. In special in the morning hours. Because it is in the Multiplus i dont want to change the settings twice a year.
I had laying around some LED drivers with the right Voltage and 900 W in total. I connected them to a Shelly controlled by Node-Red on the Cerbo GX. When the battery is under 70 % it will charge to 80 %. Works fine. But the Cerbo GX is thinking there is a 900 W consumer on AC in. And on the other hand there is a 900 W DC Source. VRM is thinking there is a 900 W consumer on the AC out because the Multiplus is in Offgrid mode. How can i solve this? Is it possible to use another EM540? Or is there an easy way to use the Shelly and let the Cerbo GX think that this is an Victron Charger?
If not possible, how can i overwrite the Ignore AC in on the Multiplus and let the Multiplus charge the batteries from 20:00 to 4:00 up to 80 %? I couldnt find it on VE.Bus System Control in Node-Red. Maybe this could be the best way so i can later add a astro clock for winter and summer.
Getting new PV Inverter to go ESS or use SmartSolar Chargers is not an option.
Thank you
BlauIstDieWelt
