Display Solar in Victron dashboard without breaking grid balance

DIY
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1

I have a Solar setup that is AC coupled on the Multiplus AC-Out connection, combined with using the Victron CT around meter tails (I didnt have space for an external meter, but needed the grid tails in order to balance grid load). This means my ‘AC Loads’ in the Victron dashboard goes to zero when I generate excess solar and the Multiplus sees this ‘negative AC load’ and automatically charges the battery - perfect!

By default my solar generation is not shown in VRM / Cerbo since it isnt ‘part of the Victron ecosystem’, however I would love to bring it in (so that I can also forecast generation and battery levels better). Ive got a CT clamp around the AC Solar connection and have tried feeding this data into NodeRed as a Virtual PV inverter (updated every 5s), however whenever I do this, the grid balance goes completely haywire and I backfeed solar generation to the grid rather than charge the battery. What am I missing to get this working, or can I not yet display PV generation in VRM without it interfereing with grid balance? (the virtual PV is configured to be on AC-out, Im running the latest firmware on Multiplus 558 and Cerbo 3.71)

In the diagram below you can see:

  • Solar is broadly flat (light blue line below the x-axis)
  • A pink line for battery charge/discharge (above 0 for discharge, below for charging)
  • A black line for net grid draw (technically there are two black lines, with one set to 0 when feeding back to the grid - effectively lost money for me)
  • Other colours are stacked usage across different household circuits
  • On the left of the big red line I was feeding solar into the Virtual PV device and you can see the black line does a weird tracking of total house power draw, but with some differences.
  • On the right of the big red line I had disabled the Virtual PV device and you can see the grid is balanced around zero (with battery absorbing excess solar)

Is there another way to do this? I guess I could add another CT and use a Shelly, but Im not sure if Id have the same problem? It seems the Cerbo is trying to do ‘something unknown’ with the solar generation and its impact on grid balance….? I have ESS assistant configured with Solar, but I dont think I can change that due to the grid balance problem…. Thanks in advance

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2

An et112 meter on your pv inverter is not an option?

3

I appreciate working around the problem is a solution, albeit different to solving the problem.

It wouldnt be easy as it would need to go in a separate enclosure mounted above my consumer unit, and not near my victron for running the cable (plus would need to remove consumer unit to get the cable out of the back. It technically is possible of course, but it would be about as difficult as putting an ET112 on the main meter tails, and that feels like it might help more…. If I go through the process why is it any different to a virtual CT with NodeRed using existing kit?