Solis inverter comms failure

[Befty]

We had our solar panels (5.6kw), Solis inverter and 7 x Pylontech US3000C batteries, set up in Oct 2022. On 31st Nov 2023 we got a UN-Vbatt alarm. The batteries dropped below 10%. We have been onto our installers who got us to reset the system a couple of times with no change. The system now powers down at night because the batteries are now in CAN-COM-FAIL and in alarm mode. We were in the process of changing electricity supplies to take advantage of low night time rates but cannot now charge the batteries from the grid. Today the installers have said we can have an engineer out on the 3rd Jan to look at the system!

As an aside, we had an engineer out a week prior to the alarms as our meter readings and solis app readings do not reflect each other. I am yet to find an explanation. They said there was a clip broken that clamps onto the mains cable so it was replaced and moved to a different spot but that everything else was fine and the firmware was up to date. That is despite acknowledgement from the engineer that the readings don’t look right.

The day after our first fault, our installation company sent out a video explaining how to change settings of the batteries to increase the battery level, that triggers a grid top up, for the winter. This leads me to suspect I am not the only person who has had this issue!

Has anyone else had a similar problem or have any ideas how to get my batteries to take a charge again?

 

[SeaGal]

Welcome, but sorry to hear of your problem.

I have Solis, but not Pylontech batteries. @rpdom on here has both, so maybe he might chip in?

It sounds as though the main issue is the CAN-COM-FAIL. Without the CANBus link between the Solis and Pylontech's the Solis will not use the batteries. A screenshot of your main Solis screen would clarify that.

Suggest you unplug and reconnect the CANBus lead between the battery and inverter in case it is a bad connection.

A complete restart of the Solis (as detailed below) would also make sense.

Can Comm Fail

My system was installed 3 months ago his morning. I have had a notification of a Can_Comm_Fail instructions say 'Restart the inverter and battery 2. If it is still not resolved, contact the factory's customer service.' Where can I find instructions on how to do this And if I have problems how...

diysolarforum.com

 

[rpdom]

I was summoned

I suspect we may have had the same installer, as mine also sent out a video about changing the settings to preserve the life of the battery. As mine are kept reasonably warm now, I ignored it. A good overnight charge will warm them up nicely and a bit of insulation round them (remove it in the summer), will keep them fine, and winter is when you want as much usable capacity from your batteries as possible.

As to adding anything to what @SeaGal (battery expert) said, I'd just check the batteries for error lights, and power cycle them anyway.

 

[Befty]

I was summoned

I suspect we may have had the same installer, as mine also sent out a video about changing the settings to preserve the life of the battery. As mine are kept reasonably warm now, I ignored it. A good overnight charge will warm them up nicely and a bit of insulation round them (remove it in the summer), will keep them fine, and winter is when you want as much usable capacity from your batteries as possible.

As to adding anything to what @SeaGal (battery expert) said, I'd just check the batteries for error lights, and power cycle them anyway.

Thanks @SeaGal and @rpdom.
Very possibly the same installer, they are suddenly taking a long time to answer phones! I will check out some insulation for the batteries.

I have reset the system two or three times as described, but to no avail. The batteries start up as normal but then head into alarm mode so I can’t do anything with them after that. Looks like I have to wait til 3rd Jan! Thanks for taking the time to reply.

 

[rpdom]

If it was the same installer (Ipswich based?), their engineers are fairly good. I had a problem with my first inverter and they sent someone out to look (yes, I had to wait a while too). He upgraded the firmware on the batteries and inverter and checked all the connections were good. Unfortunately the fault kept happening, just not while he was here.

They sent out another engineer, who did more tests and checked all of the wiring. He could see the faults being logged at the time. After much head scratching he realised that the inverter was underspec for the panels I have and the MPPT voltage was occasionally going too high and the inverter was rebooting. A couple of weeks later they swapped the inverter for a newer model and the fault went away.

 

[SeaGal]

I was summoned

.. sometimes you just have to call the experts in

Too low temperature, for sure, will cause issues, so that would be good to address anyway.

I'd not expect a CAN-COM-FAIL message to be triggered from just low temp though - though, of course, we don't know yet whether that is the cause of the symptom or a symptom of the cause.

@Befty... did you try unplugging and reconnecting the CANBus cable?

Looks like I have to wait til 3rd Jan!

In the meantime, can you send a picture of the inverter's main screen?

Also, check the alarm log screen. I'm not in front of my inverter, but from memory go to the main menu (by pressing enter twice), then down one to ?Advanced, then select Alarm messages - interested to see if there are multiple CAN failure message on the first page or two there.

 

[Befty]

Thanks!
@SeaGal Is the CANBus cable easily identifiable. I did unplug the comms cable that goes into the master battery one of the times I restarted the inverter.

When you say the main screen, do you mean the schematic screen?

There are a lot of alarms - I have attached a selection from the app.

@rpdom yes, it must be the same people. Once the engineer comes out they do seem very knowledgeable but getting to that stage takes a while!

 

[SeaGal]

Thanks!
@SeaGal Is the CANBus cable easily identifiable. I did unplug the comms cable that goes into the master battery one of the times I restarted the inverter.

That's the one - it's the RJ45 connector that plugs into your battery pack.

When you say the main screen, do you mean the schematic screen?

Yes, but I can see the errors from the app thing, so don't worry.

There are a lot of alarms - I have attached a selection from the app.

Not looking good If it were me, I'd be so frustrated to wait that long, I'd be testing each of the 7 US3000C's individually with the Solis to try and determine where the issue laid... but that would take a bit of re-configuration.

... Once the engineer comes out they do seem very knowledgeable but getting to that stage takes a while!

I'd hate that . I get a sub 5 minute response call out for my system... but then I'm the designer, maker, installer and support engineer rolled into one ?‍??‍?‍??‍?

 

[dezfutak]

. I get a sub 5 minute response call out for my system... but then I'm the designer, maker, installer and support engineer rolled into one ?‍??‍?‍??‍?

I can definitely relate!! I now have two DIY batteries that I'm managing (one is 200 miles away, the other a 30 second walk to the attic)