After replacing a failed MPPT 450/100 my off grid system stopped synchronising. While I have successfully restored normal system operation, I’d like to ask whether experts or Victron engineers can confirm or correct what I found. I seem to have solved it when I discovered that my original working 1-input MPPT and the Color Control GX were both set to Device Instance 0 on the VE. Can Bus. The new 2-input MPPT (a loaner from my installer) had been modified to a different instance number by a previous user.
As soon as I changed the new/loaner MPPT’s VE.Can Device Instance to 0, the system instantly self-corrected. Both MPPTs paired back up, began communicating with the Color Control GX properly, and synchronised their charging stages again—bringing our absorption times back to what we expect this time of year.
System Setup (an off-grid system that had been working well since 2019):
Solar Array: 9.7 kW total split into 3 arrays (36 panels altogether, south-facing ground mount)
Inverter 2 x MultiPlus-II 5000VA in parallel
Battery Storage: 48V/2000Ah lead-acid (FLA)
Battery Monitoring: SmartShunt (VE Direct connection to Color GX)
Control/GX: Color Control GX with DVCC enabled
Solar Chargers: 2 x SmartSolar MPPT 450/100s on a daisy-chained, terminated VE.Can bus network.
MPPT#1(Original): with 1 input (12 panels) — Still running fine.
MPPT#2(Loaner): with 2 inputs (12 panels each) — Replaced the failed unit.
This is the background if you want to read further:
My original 2-input solar charger suffered a hardware failure. My installer provided a loaner MPPT 450/100. After copying our battery charging profiles over, we noticed the new loaner did not synchronise with my original 1-input unit. Before the failure, both MPPTs respected the SmartShunt data via DVCC and transitioned through Bulk, Absorption, and Float together.
There was no synchronisation, the MPPTs performed their charge stages at very different times. This meant our total daily absorption time was at least twice as long as it should have been, as one absorb charge began about ½ hour after the other, resulting in the lead-acid bank being overcharged. (although I began switching off some of the PV each day until this was solved.) For information, the startup times of the two MPPTs was only one minute apart each day.
My assumption had been that each networked device would need a unique ID. Instead, it appears that for parallel MPPTs operating under DVCC with a Color GX, all devices must share Device ID such as 0 – as though 0 identifies the network/group rather than an individual device.
Is this the correct and intended configuration?
Can an expert confirm whether keeping all parallel VE.Can MPPTs on Device Instance 0 (or at least the same Device Instance number) is the explicitly required behaviour so that DVCC can use the Smart Shunt to synchronise them? If yes, what should the Device Instance number of the Color GX be?
Can instance grouos a set of can devices, each device can have a can id on that can bus.
Its not entirely unique to a victron system just how can works. Even can bus in vehicles is set up like this.
A short google search would have answered that.
@VWard
Just a warning about AI use. Even to structure posts - it makes them ultra (and unecesarily) long. It is against community guidelines. Please edit it.
I used Claude to help me focus this post. I edited it myself extensively. Please accept this post it really is no longer than it needs to be. My own version was far more rambling than this. Perhaps you are concerned because I call myself a beginner and that is possibly an exaggeration. But I’m not DIY, I’m not a professional. I’ve studied everything to do with my Victron installation extensively because it is off grid and I need to understand.
Were all of the guildines followe when the mppt was put in place?
Even though it is a loaner ALL firmware in the system would be updated when changes are made.
Checked that programming was in place?
This is normal as the mppts have different start up voltages.
One is 5v above battery the other is 120v.
A slightly longer absorption is not damaging for Flooded lead acid battery banks. It is good for balancing. Usually bulk on FLAs is about 85% of charge cycle anyway.
The battery configuration we set up originally has worked well for us since 2019. And we did update all firmware when we brought the loaner in. And I only mentioned the startup times because it seems relevant to the fact that the MPPTs were doing absorb charges more than ½ hour apart.
You say that a short google search would have answered this. It did not. Please can you tell me where it is documented on the victron site. The only thing I could find about groups was documented as VE Smart Networking, and I’m not using VE Smart Networking, only VE Can Bus
For DVCC and no intelligent battery not using ess since you are offgrid, the mppts will each use their internal charger settings using the shunt as a voltage base. It is documented as such.
The only thing i can think of for different behaviour in your current set up could be programming or firmware since they are technically the same mppt.
Alternatively in the physical change something is not sutting right in torque or connection.
Thank you for your reply, just to make this clear, once I set the Color GX and both MPPTs to Device ID 0, it all started working.
And Thank you for that link. I’m afraid that all I can find regarding device instances seems to be this, and it isn’t clear to me that all devices should be Device ID 0:
It talks about Device Instances, Data Instances, PGNs, and System Instances. But nothing about Device IDs which is the parameter that the VRM asks for.
They don’t document it exactly as its not their invention and is not particular. They are using a known standard. They do state what their standard is. I mentioned it before.
Then there is other documents for the vregs and other if integration is something you are into.
Questions about that are more suited for the modification spaces. So start a new thread there if that is what you are wanting to do.
Yes, I saw that document when I was trying to work out what was going on, but I feel that this is not well documented, apologies for the criticism of Victron. I have seen a lot of people post to this forum on pretty much the same topic with no answer. There is a long video on Youtube from someone in Australia on the same topic and he is only able to solve it with VE Smart Networking which isn’t an option for me.
Its more because when you are paying with stuff like that there is background knowlege you would get through formal training and qualifications.
And because its not a victron specific thing that they invented its not on them to document it. That is like asking a toatser manufacturer to write a manual about the house wiring standard they plug into - its not their place.
Learning it DIY involves trial and error and alot of the error.
How much longer is your absorption? Is everything programmed and uodated the same these are questions i had asked but you hadn’t addressed? Also do you have any custom integrations? Sometimes those cause issues.
I agree about having to experiment and over the years have had help from my battery manufacturers, from installers, from this forum and the original, old Navitron Forum. This time of year (since middle of February) my batteries go between 97 and 100% every day and the absorption, when it is working, is between 7 and 20 minutes each day. While the MPPTs had different Device IDs, the absorption time altogether was 1.5 hours. I was topping up the water in the batteries every day and google searches confirmed that even this might still result in damage to FLA’s.
I don’t have any custom integrations, the only problem seems to have been the VE Can Bus number in the loaner being different. My installer who is very helpful didn’t know the answer to this either so I thought I’d put a post here to get confirmation. Thank you.
I can’t agree with you regarding toasters and where they plug in. Victron’s VRM asks for a parameter called Device ID, but there is no explanation and no documentation of what a Device ID is and what the significance of changing the Device ID away from the default will be. No information about how to get synchronisation from parallel MPPTs daisy chained and terminated on a VE Can Bus network. It isn’t like plugging in a toaster.
I am glad I stumbled on the answer last week and that today you have, as I requested at the beginning of this post, confirmed that Device ID refers to the VE Can Bus, therefore all devices (mppts etc) sharing on that bus must share the same ID. I hope this helps others.
You have misread/misunderstood the device # is the CAN instance number.
Each device already has its own ID based on its hardware Serial number which it announces on the can bus. You cannot see it on the GX but they do it so they can be addressed and their information recorded.
If you change the instance # it separates it into a different can and that will change how DVCC interacts with it. Linked documents will tell you it removes the control.
This is a known protocol not a Victron special thing. It is documented by the makers of the said protocol.
The victron documents what protocol they use.
