GUIv1 and GUIv2 disagree on the same MPII

Been wrestling with something similar on my van build's shore power setup, but I've seen this crop up loads on residential MPII installs too so figured I'd throw it out here.

Anyone else noticed that GUIv1 and GUIv2 on the Cerbo GX seem to fundamentally disagree on where power is coming from? I've been poking around a friend's home ESS setup — MPII with a couple of Fogstar Drift 200Ah batteries and a decent Victron MPPT — and after updating the Cerbo firmware the two interfaces are basically telling different stories.

GUIv1 shows grid and solar quite cleanly and sensibly. GUIv2 seems to be double-counting the solar input somewhere, adding it into the grid figure rather than treating them as separate sources. End result is the dashboard shows the grid apparently importing far more than it actually is, which is obviously wrong and would drive anyone trying to optimise their ESS settings absolutely mad.

My suspicion is it's a display logic issue introduced somewhere around the 3.x firmware branch rather than anything wrong with the underlying data — VRM seems to log correctly from what I can tell.

A few questions for the group:

• Has anyone confirmed whether this is a known bug Victron are tracking?
• Does it affect all MPII configurations or is it specific to certain ESS assistant setups?
• Any workaround beyond just reverting to GUIv1 as your default?

Would be curious whether those of you running Quattros rather than Multis see the same thing, or if it's isolated to the MPII ESS assistant specifically. Drop your firmware version and config below if you're seeing this.

HappyWelder | 📍 Yorkshire | ⚡ 48V LiFePO4 | 🔧 Certified welder, amateur sparky

@WhatsAFuse the GUIv1/GUIv2 discrepancy is a known headache mate. From what I've seen, the two interfaces sometimes pull data from different registers or refresh at different intervals, so you end up with values that look contradictory but are both technically "correct" at different moments in time.

Worth checking whether your MPII firmware is fully up to date first, as Victron have patched some of the reporting inconsistencies over recent versions. Also, are you comparing figures at exactly the same moment, or could there be a lag between the two displays?

What specific values are disagreeing for you - watts, SOC, something else? That'll narrow it down considerably. The fix is often simpler than it looks once you know which parameter is actually misbehaving.

Seen this exact thing on my narrowboat's MPII — GUIv2 was showing float when GUIv1 clearly had it in absorption. Drove me mad for a week thinking my Victron settings were borked.

Turned out the two interfaces poll the data at slightly different intervals, so if something's mid-transition you can catch them out of sync. Not a real discrepancy, more of a timing artefact.

Worth checking:

• Are both showing the same SOC figure?
• Is it consistent or does it only happen during charge phase transitions?

If SOC matches but charge state label differs, it's almost certainly just the polling lag. If SOC is also disagreeing, that's a different rabbit hole entirely — possibly VRM portal caching vs local data.