I have been dealing for some time with a problem in an installation that I did not set up myself.
I have a three-phase, grid-connected self-consumption installation with batteries.
The components are as follows:
3 x MultiPlus-II units with the same firmware and version; all three are MultiPlus-II 5kVA
4 x Pylontech US5000C batteries
3 x SmartSolar MPPTs
1 x Cerbo GX
1 x VM-3P75CT meter
The installation is currently wired as follows:
From the MCB, it goes to a four-pole RCD, and the phases are distributed as follows: inverter 1, master, L1 + N; inverter 2, slave-1, L2 + N; inverter 3, slave-2, L3 + N. Each cable is connected to the AC IN of the corresponding inverter. Nothing is connected to the AC OUT 1/2 outputs.
It has been verified that the phases from the main isolator correspond as follows on each inverter: L1 = L1, L2 = L2, L3 = L3.
The inverters have been connected via VE.Bus from the Cerbo to the master, from the master to slave-1, and from slave-1 to slave-2.
The firmware of each inverter has been updated, the three-phase system has been configured using VE.System Configurator, and then each ESS has been configured individually, from the master through to slave-2.
The meter is connected to the Cerbo GX using a VE.Can cable.
The problem is that it does not synchronise with the grid and the relay does not close, so it cannot supply power from the batteries to charge them, which defeats the purpose of the self-consumption system.
The meter reads the loads perfectly, and the batteries are connected and recognised by the Cerbo.
I have restarted the inverters twice and configured everything again, but I always have the same problem: I get the message „AC input active - disconnected“.
I could route each phase through its corresponding inverter and take it out through AC OUT, but I am not interested in doing that because of the load the inverter might have to handle with a 63A power input.
Previously, this system operated in parallel without any apparent problems when the installation’s grid supply was single-phase.
I have gone through the manuals, videos, etc. more than once, but I cannot find the cause of the problem.
I would be grateful for any help you can provide.
Thank you very much.
Sounds like that was done.
But to check, do you have 380V output when tested? Yes i know you have nothing connected but it matters to check.
A random silly thing to check, has the system been put into inverter only using software switch on the GX?
On the GX do you have the system configured with no loads on the output , the grid meter set to the VM?
Its not a phase rotation or connecting error, the system would say that specifically.
Are you using a grid code? Is the input frequency and voltage range in the correct range at the inverter terminals?
Last but not least check voltage between ground and neutral
Hello, thanks for replying.
Yes, the systems have been reconfigured successfully and updated (resetting the values during the update), the three-phase system has been configured, and each ESS has been loaded individually using a saved file.
“But, to check this, do you get an output of 380 V when carrying out the test? Yes, I know you don’t have anything connected, but it’s important to check.”
Yes, in this case I haven’t measured the voltage at the ACOUT1/2 output because nothing is connected. I’ll do so in the next test, but the CerboGX console was showing 230 V on each phase, and I also verified that the phases were not reporting any problems according to the Cerbo.
“It’s not a connection or phase-sequence error; the system would indicate this specifically.”
Exactly, I carried out the test and the system reports “phase rotation”.
“Are you using a grid code? Are the input frequency and voltage range within the correct values at the inverter terminals?
Finally, check the voltage between earth and neutral.”
In this case, the grid code is correct: Spain’s RD1699/2011 | UNE 206007-1:2013IN.
Yes, I’ll try to attach an image. The input frequency is 50.4 Hz, with a maximum of 51 Hz, and the voltage is within the specified parameters: L1 = 240; L2 = 232; L3 = 236, with a maximum of 253 V.
“Finally, check the voltage between earth and neutral.”
In this case, it was a phase rotation change we made as a test to see whether it detected the rotation.
The phases run from left to right; in our case, “R-S-T = L1-L2-L3”, with L1 as the master.
