DESS stops compensating self-consumption

Anyone else noticed DESS going a bit daft after a recent firmware update on their Victron kit?

Running a fairly typical static caravan setup — Multiplus-II, Cerbo GX, decent Fogstar lithium bank — and since whatever update it pushed last week, the thing has completely stopped doing what it says on the tin in trade mode.

Specifically: when Octopus export rates are decent (and they have been lately, proper tasty), DESS is deciding to flog everything to the grid rather than covering my own loads first. So instead of self-consumption being handled sensibly, I'm simultaneously exporting AND drawing from the grid to run the kettle. Absolute nonsense, costs me money, defeats the entire point.

Before the update it worked a treat — sell high, but don't be stupid about it, cover your own house first. Now it's like it's forgotten self-consumption compensation is even a thing.

Has anyone else seen this, particularly on UK Agile or Flux-type tariffs where the export/import spread actually matters? And more importantly — is there a known fix short of rolling back firmware, because I'd rather not spend my Sunday afternoon doing that particular dance again?

Worth noting I've not changed anything in my VRM schedules or DESS settings. Only variable is the firmware version, and the timing is pretty damning.

@Rob1963 had something similar on the boat last autumn — not DESS specifically but the Cerbo started making odd decisions after a VRM firmware push. Turned out the self-consumption calculation was pulling stale data because the DVCC settings had quietly reset themselves. Worth checking your DVCC page on the Cerbo — specifically whether STS (Shared Temperature Sense) and SVS (Shared Voltage Sense) are still enabled. Mine had both toggled off without me touching anything.

Also double-check your ESS minimum SOC value. After one update mine had jumped from 20% to 50%, which completely threw off how the system was compensating overnight.

Fogstar batteries or any Pylontech-style comms involved? Sometimes the BMS handshake gets disrupted post-update and DESS loses confidence in the SOC signal entirely.

@Rob1963 had this exact scenario play out in my cabin last spring — Multiplus-II, Cerbo GX, Fogstar Drift cells. After a firmware push the ESS assistant seemed to lose track of self-consumption entirely and just sat there exporting cheap solar rather than offsetting loads properly.

Worth checking a few things:

• ESS minimum SOC — sometimes resets to default after updates
• Grid setpoint — mine had silently shifted to 0W instead of my usual -50W
• Assistant version — pull it up in VE.Configure and check it hasn't reverted

The grid setpoint issue was my culprit. Ten minutes in VEConfigure3 sorted it. Annoying that it doesn't warn you when parameters shift on update.

If that's not it, pull the VRM logs and look at the Grid L1 graph — you'll see exactly when it stopped compensating.

Narrowboat here, Cerbo + Multiplus-II combo. Had something adjacent happen after a firmware push — DESS basically forgot my consumption baseline and started grid-importing at odd times.

Worth checking your VRM portal — look at the self-consumption graph over a few days. If it's flatlined or showing spikes that don't match your actual loads, the algorithm's likely lost its reference point.

Fixed mine by doing a full ESS reset rather than just a Cerbo reboot. Settings > ESS > scroll to the bottom. Bit nuclear but it recalibrated properly within 24hrs.

Also check which firmware you're actually on — Victron's changelog sometimes buries relevant ESS fixes in minor point releases.

@Rob1963 worth checking whether your VRM portal is actually reporting the correct AC loads to the DESS algorithm — I had a period on the boat where the Cerbo was reading phantom consumption figures, completely throwing off the optimisation logic. Turned out to be a CT clamp orientation issue that a firmware revision had somehow... interacted with badly.

Also, if you haven't already, cross-reference your DESS schedule against what ESS Assistant version is actually installed on the Multiplus-II itself. There's a known mismatch scenario where DESS pushes settings the ESS Assistant isn't quite expecting — particularly around the self-consumption priority thresholds.

VE.Configure → ESS tab, check your minimum SOC without grid loss value hasn't drifted. Mine reset itself silently once after an update.