Bug: Grid setpoint overrides Peak shaving, Dynamic ESS Maximum export power and Limit system feed-in

Q&A and troubleshooting DESS
, , ,
1

With the Victron ESS system you have 3 ways to limit your system export power. Even after setting strict limits on how much power can be exported, the system is either completely or partially overridden and ignores your set limits when you set the grid setpoint to be more negative than your configured max export limits.

For example imagine you set the following 3 limits:

  • VRM > Remote Console > Settings > ESS > Grid Feed-in
    • “DC-coupled PV - feed in excess” - turned on
    • “Limit system feed-in” - turned on
    • “Maximum feed-in” - Limit set to 100w (smallest available setting)
  • VRM > Remote Console > Settings > ESS > Peak shaving
    • “Peak shaving” - Set to always
    • “Limit system AC export current” - turned on
    • “Maximum system export current (per phase)” - Limit set to 5A (smallest available setting)
  • VRM > Settings > Dynamic ESS > System
    • “Can you sell energy back to the grid?” - Turned on (“Yes”)
    • “Maximum export power” - Limit set to 0.1 kW (smallest available setting)
    • “Operating mode” - Set to “Green mode”

With the above precautions there should be no possible way to export more than 5A to grid for any considerable length of time (even the 0.1 kW limit inside dynamic ess maximum export power should be a hard cap imo), a short spike for a few seconds is acceptable, while for example a minute of disobedience is unacceptable and wrong. The firmware that Victron currently provides for ESS systems fails to limit export to the maximum of the above limits. Such a system would never pass DNO tests and may not be safe. Victron needs to fix these issues. Below are the results of my tests and how you can test this at home from your remote console, if you want to repeat these outcomes and you have DNO approval to do these tests:

Go to:

  • VRM > Remote Console > Settings > ESS > Peak shaving
    • “Peak shaving” - Set to always
    • “Limit system AC export current” - turned on
    • “Maximum system export current (per phase)” - Limit set to 5A (smallest available setting)
  • VRM > Remote Console > Settings > ESS > Grid setpoint
    • (If allowed by your DNO) Set the Grid setpoint to -3,600w as a test.
      • Result: The system slowly ramps up and eventually exports a peak of around 6A. Test fail.

For clarification on my setup, we have:

  • Cerbo GX
    • v3.40
  • MultiPlus-II 48/5000/70-48 (three units in parallel, single phase)
    • v510
  • SmartSolar MPPT VE.Can 250/85 rev2
    • v3.16
  • Carlo Gavazzi EM112 single phase energy meter after DNO mains fuse.
    • Configured as a grid meter inside the remote console.

Results from my tests:

  • VRM > Remote Console > Settings > ESS > Peak shaving
    • “Maximum system export current (per phase)”
      • Set limit to 5A was only capable of limiting exports below 6A
      • Set limit to 6A was only capable of limiting exports below 7A
      • Set limit to 7A was only capable of limiting exports below 9A
      • Set limit to 8A was only capable of limiting exports below 10A
      • Set limit to 9A was only capable of limiting exports below 12.5A
      • Set limit to 10A was only capable of limiting exports below 12A
      • Set limit to 11A was only capable of limiting exports below 13A
      • Set limit to 15A was only capable of limiting exports below 16A
      • Set limit to 20A was only capable of limiting exports below 24A

Based on these tests, I found that the “limit System AC export current” setting is only accurate within 20% of the configured value. So instead of limiting the system export to the configured value the system allows sustained exports of up to around 20% higher than the configured value.

Comments and feedback welcome. Happy to provide further details. Hopefully Victron will address this in future revisions. FYI I’m based in UK, so 10A here is ~2,300W at mains voltage.

2 Likes
2

Yeah, I’ve noticed the same thing with my Victron setup. Did some tests on my system, and I’m seeing the exact same issue. It’s like the export limits are just a suggestion rather than an actual cap. I’ve got a similar setup—Cerbo GX, MultiPlus-II, and SmartSolar MPPT. Limits set to 5A, but I’m getting sustained export closer to 6A. The system is definitely happy to overshoot by 20%. This shouldn’t be happening, seems like something that could easily be patched with a new firmware.

Honestly, kinda frustrating. I hope they roll out a fix soon.

1 Like
3

Look up active and reactive power.
Then there is the ESS LOM detection as well, some push back to the grid is expected.
Sometimes the angry pixies don’t like to be wrangled.

1 Like
4

Thanks for the input, but I think the issue here is more straightforward. The Carlo Gavazzi EM112 meter I’m using is measuring active power—the actual power being exported to the grid. So, the 20% overshoot I’m seeing isn’t about reactive power or something the system is misreading; it’s a real increase in the active power being fed back to the grid.

Some momentary pushback over the configured system limits would be perfectly normal to see, but a consistent 20% overshoot suggests there’s something off in how the system is enforcing the export limits. Something that Victron should fix with a firmware update because currently the power that’s being exported is more than what’s configured, which is a pretty serious issue, especially for staying within DNO limits.

5

Problem is likely in the current sharing in the parrallel set up.
How well are they balanced?

1 Like