I have mounted a VM-3P75CT but when the solar panels are active, the watt measurement of the VM-3P75CT almost seems random.
Solar panels are enphase and connected to AC out.
What’s wrong?
When the multiplus has finished charging, the measurement of the VM-3P75CT is reasonable stable within a 100 watt range with 2000 watt grid feed in from the solar panels. It almost seems that the grid measurement control loop creates a a lot of fluctuation.
I have the same problem.
I have 3x 3P75CT meters. Grid, Enphase connected to AC-IN and Enphase connected to AC-OUT.
- If there is no sun or a lot of sun, all 3 meters are working as expected
- If there is little to no sun, only Enphase AC-IN is working as expected. Both Grid and Enphase AC-OUT are going up and down and it also seems to be moving across L1, L2 and L3. Sometimes even by as much as 200W
Some observations:
- if I keep the stats for AC-OUT open in remote console, the numbers are also going up and down but are far far more evened out. They seem still incorrect and more or less confirm the changes jumping over L1,L2 and L3. This makes it hard to believe it’s just measurement error?
- If I pull the breaker on Enphase AC-OUT and put the power back on, the behaviour does not start immediately. The Micro’s (IQ7a) are generating but the odd behaviour starts only after a few minutes
- I checked the assistant, it’s configured for s50.2 - m51.7 - d52.0 and if I emulate that by pulling the AC-IN breaker and use DVCC to manipulate the charger the Micro’s are throttling as expected
- I changed all three assistant to not “have PV”. And again using DVCC confirming frequency shifting is not applied. But the readings are still heavily fluctuating
Exhausted all options and have now submitted a support case with Enphase asking them for release notes. For me all that remains is that the 12 IQ7a Micro’s at AC-IN are on an earlier firmware than the 8 IQ7a Micro’s connected to AC-OUT.
In the attached video’s you can see the system running in early morning with and without the AC-OUT (PV2) micro’s connected. You can clearly see the high resolution of the grid meter and PV2 picking up on the way the micro’s inject the power to the grid. With those micro’s disconnected, the 12 remaining micro’s on the older firmware do not seem to trigger that behaviour on grid and PV1.
As mentioned earlier, the first 5 mins after power-on, everything is stable. Not sure how that fits in.
Odd behaviour with PV2 powered on:
No problem once PV2 is powered off:
No response from Enphase yet but it’s the only option that remains. The most likely cause is that Enphase are using their burst mode more aggressively and during longer periods of low lights instead of just during shading.
I have seen the behaviour before but never as extreme as this and most certainly not with such a huge difference between 2 firmware versions. Burst mode is known to cause this behaviour. Specially if you have a large amount of panels, the reading can go up and down with a few 100s of W during low light and shading.
I know Victron is working on slowing down their sample rate for meters set for PV. Think the latest beta already includes this if connected via can instead of ethernet. With ethernet soon to follow. Let’s hope the result will be smoothening or averaging not simply a lower resolution to Cerbo.
But that does not smoothen the grid readings. The difficult thing is that it seems there is nothing to fix here. At the time of the reading the sample actually is correct. It just looks a bit broken due to the use of capacitors.
Installed a victron current sensor on the pv panels today. The watt reading of the victron current sensor is pretty stable, but the VM-3P75CT watt reading is still going all over the place.
I doubt if the victron can keep a good 0 watt grid setpoint.
I have On phase 3 also enphase solar panels I also got very strange readings on the energy meter today. Have you found a solution yet. See my post:
No solution yet but I know it’s under investigation and there will be an update for the VM-3P75CT.
And there are 2 issues to distinguish:
- Enphase Burst Mode in the morning and the afternoon during low light
- Oscillation between the VM-3P75CT and the Multiplus trying to regulate
Burst mode (1) of enphase can give fluctuation in power measurement, I don’t know if it can be disabled but it’s only in short periods and doesn’t really hurt.
The oscillation (2) is something that Victron could solve. It seems that the multiplus is to aggressive in its mission trying to keep the grid at a certain setpoint (which is often 0), causing overshoot and undershoot and I think this is where they are working on.
Thank you for the feedback. I have also reported this to the supplier where I purchased the meter. My system is now running properly again now that I have switched off the grid meter and am using the inverters as meter. This is possible because all groups are behind AC out 1. ESS 3 fase is working again.
Do you know whether the EM24 energy meter functions properly and does not have these kinds of problems with enphase? Othewise, I can suggest to my supplier that they switch the VM for the EM24.
However, installing the EM24 in the meter cupboard will require quite a bit of modification.
Thanks again for your feedback.
There is a firmware update (v1.10) for the VM-3P75CT. I just installed it, maybe you can try if it makes it better.
I will try this tomorrow and let you know. I check for updates but there was nothing two day ago.
Okay, perfect.
I don’t have any experience with the EM24 so I can’t say anything about that.
I couldn’t wait until tomorrow, so I took another look at the new firmware update.
Victron Connect indicates that I already have the latest version.
Did you install the firmware manually?
There’s an option to update via VRM which worked for me.
Victron Connect on my iPhone was also showing v1.08 as the latest available via that method.
I will also do it with VRM tomorrow. Now there is maintaince on the vrm portal.
I did the update to v1.10, but I saw the energy meter twice in the list, once updated and then both updated, which was strange!
The firmware update did not resolve the issue. For me, the issue only arose three days ago; prior to that, everything seemed to be functioning properly for a long time. Therefore, I find it peculiar that L3 is suddenly no longer being measured correctly.
I took three more measurements and made a video of them.
Video 1.
VM-3P75CT Firmware 1.8
ESS meter set to inverter/charger
Video 2
VM-3P75CT is completely switched off.
ESS is set to inverter/charger
The GX now displays the measurement of the inverter/charger.
Now updating the firmware and test again.
Video 3.
VM-3P75CT Firmware 1.10
ESS meter set to inverter/charger
I haven’t checked the meter box yet, but I don’t expect there to be anything wrong with the clamps.
I check the glams, see this post
2-9-2025
For me the problem is solverd, everything has been working fine for a few days now. The ESS is keeping everything at zero to the mains. The cable tie and the firmware seem to have solved the problem. I will keep an eye on it.
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