Revised immerSUN Monitoring

I have re-worked the monitoring solution for the immerSUN solar PV diverter which is responsible for measuring the house’s electricity consumption, the import of electricity from the grid, the solar PV generation and any diversion of excess solar generation to the domestic hot water cylinder’s immersion heater.

Previously the monitoring was done by extracting data from the webpage every minute and storing it in InfluxDB for visualization using Grafana. This worked OK but missed a lot of the details of how the readings change on a more dynamic basis. The immerSUN unit actually sends data in the form of a 56-byte UDP Datagram every 5 seconds and since this data is traversing the local network anyway it seems a shame not to extract the readings “on the way past”. While not trivial, since the format of the 56-byte Datagram is not published, it’s not that hard to reverse engineer where the different readings are.

There’s a (draft) write-up of the solution under the Technical Articles here.

CC BY-SA 4.0 Revised immerSUN Monitoring by Marsh Flatts Farm Self Build Diary is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

2 thoughts on “Revised immerSUN Monitoring

  1. Hello,
    It’s most interesting reading your notes in your “Marsh Flatts Farm Self Build Diary”, I came to look at it because of references in the Facebook Group “Immersun, Eddi, or Zappi Users Community”.

    I’m searching for a solution to a problem that’s similar to your ImmerSun/ImmerLink problem. My ImmerSun is of 2011 vintage and doesn’t have the same menus, particularly it doesn’t allow access to the MI UserName and Password and more crucially, it doesn’t allow me to see or change the IP address of the MI Gateway. The Sun and Link units are communicating but I have no idea what they’re trying to link to as am MI Gateway address. I can connect to the address using PING and TELNET so I don’t think I have a Router or Firewall problem.

    My reason for leaving this feedback is to ask if anyone else has contacted you to talk about the same problem? I have a reasonable IT knowledge base but I’m stumped.

    • Hi Peter,

      I’ve not had any contact from anyone else reporting the same problem. It sounds like your 2011 unit is rather older than mine – I understand there are Mark 1 and Mark 2 units and yours is presumably a Mark 1, which might explain the menu differences (or maybe it’s just running an older version of the firmware). is the ‘new’ server address. My hunch is that your unit is trying to use the ‘old’ server address,, and doesn’t appear to give you any option to change that.

      Assuming that is indeed the case, the only thing that comes to mind is similar to what I’ve done for the revised monitoring, where I tell my router to redirect any traffic meant for one IP address (i.e. the old one) to a different IP address (i.e. the new one). Your router might not give you the option to do that though.


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