EVCS NS: "Session cost" vs "Session savings" wrong when charger is upstream of the MultiPlus

Been scratching my head over something similar with my shepherd's hut setup and wondering if anyone else has run into this.

I've got a Victron EVCS NS (also on v2.09) but mine sits downstream of the MultiPlus-II GX rather than upstream — and I'm still seeing what look like dodgy figures in the "session cost" vs "session savings" display. The savings figure seems wildly optimistic compared to what I'd actually expect given my solar yield and battery state at the time of charging.

Makes me wonder: is the EVCS pulling its cost/savings data from the wrong reference point regardless of where it's physically installed in the circuit?

A few questions for those who know this better than me:

• Does the charger's position (upstream vs downstream of the MultiPlus) fundamentally change how energy flow is measured for billing/savings calculations?
• Is this a known firmware quirk, or am I missing a VRM/Venus OS config setting somewhere?
• Has anyone tried forcing a manual tariff rate in the EVCS settings to see if the session cost figure then makes more sense?

I'm also running Fogstar cells on a 48V bank with a Renogy MPPT, so the whole system talks through the GX device — not sure if that's relevant to how the EVCS logs its data.

Would be good to know whether this is worth raising with Victron support or if there's a community workaround already floating about. Anyone had a proper dig into this?

Hey @AshDweller, interesting that yours is downstream rather than upstream - that's actually the more typical installation position so curious whether you're seeing the same cost/savings mix-up or something slightly different?

With the EVCS downstream of the MultiPlus, the system should have a cleaner picture of what's coming from grid vs solar/battery, so theoretically the session cost calculation ought to be more accurate. Are you actually seeing incorrect figures, or is it more that the savings column shows zero even when you've clearly been charging from solar?

Worth checking what your grid meter setup looks like - are you using a separate energy meter or relying purely on the MultiPlus measurements? That can make a real difference to how the EVCS attributes the energy source.

Also, what firmware is your CCGX or Cerbo on? Sometimes the portal calculations lag behind the EVCS firmware updates.

Good point from @Ollie1991 there. Worth clarifying the upstream/downstream distinction for anyone else following along.

When the EVCS sits upstream of the MultiPlus (between grid and inverter), the charger sees raw grid current but Venus/CCGX has no visibility of that consumption before it hits the AC-in sense point. Result: session cost/savings calculations go haywire because the energy accounting assumes all EV draw flows through the MultiPlus metering.

Downstream (between MultiPlus AC-out and the car) is the canonical Victron-supported topology for exactly this reason — the MultiPlus current transformers catch everything properly.

@AshDweller — if yours is genuinely downstream and still showing duff numbers, I'd check:

• Grid meter type set correctly in Venus OS (Carlo Gavazzi vs internal CT)
• Whether ESS assistant is active
• VRM portal → Advanced → raw L1 current figures during a session to isolate where the discrepancy appears

What firmware is your CCGX/Cerbo on?

Really useful clarification from @ExSquaddie49 there. Quick question though — when the EVCS sits upstream of the MultiPlus, does the GX device still see the charger's consumption as a separate entity, or does it just lump everything together into the grid/load figures? Asking because I'm trying to plan a similar setup in my motorhome conversion and I can't work out whether the "session savings" calculation would even have meaningful data to work from if the metering topology is wrong. The Victron docs on this are frustratingly vague. Has anyone actually verified what the EVCS NS is pulling its cost/savings figures from — is it the meter data, the GX calculations, or something hardcoded in the charger firmware itself?

Don't have an EVCS myself but I do watch the Victron changelog pretty closely for my garden office setup — there's a known bug logged on the Victron community forum about exactly this upstream scenario affecting the session cost calculations. Pretty sure it was flagged around the v2.08 release.

@MultiPlusGeek the short answer is the EVCS can't accurately see what energy is coming from solar vs grid when it's upstream of the Multi, so the savings figure ends up being calculated on bad data. The "session cost" vs "session savings" figures essentially diverge because the energy metering reference point is wrong.

Worth checking the Victron Community forum — there were a few threads on this with devs commenting. Might be a firmware fix already in the pipeline for v2.10.

Really interesting thread this. @MultiPlusGeek raises a fair question about the upstream scenario — from what I understand, when the EVCS sits upstream of the MultiPlus, the meter readings the charger sees don't account for what the Multi is doing with stored energy, so the "session savings" figure gets confused about what's actually grid-sourced versus battery-sourced. Ends up attributing savings incorrectly.

@MeganFox — would be curious what you've spotted in the changelogs around this. I've been watching v2.10 release notes but nothing specific addressing the metering logic yet.

My own setup has the EVCS downstream so I've avoided this particular headache, but I did have odd session cost figures until I got the grid meter configured properly in VRM. Worth double-checking your meter assignment in the CCGX/Cerbo settings @AshDweller if you haven't already — sometimes that's the culprit.