EV charging : cannot get more than 2kw of solar power

Been wrestling with something similar for a few weeks now and it's doing my head in.

Running a Victron MultiPlus-II 5000 with a Cerbo GX, ESS active, and a decent Fogstar 48V battery bank out in the garden office setup. Got a basic AC EV charger on the output side. Problem is, no matter what I throw at it, I can't seem to push more than roughly 2kW of solar into the car. Rest just dumps into the battery or gets throttled back.

Suspect it's the ESS algorithm being overprotective — it's clearly prioritising the battery over everything else, which fair enough, but on a sunny July afternoon when the bank's already at 95% I just want to shove that surplus straight into the car.

Tried fiddling with the minimum SOC settings and adjusting the feed-in compensation, didn't make a blind bit of difference.

A few things I'm wondering about:

• Has anyone actually cracked this with a Node-RED flow on the Cerbo? I've seen vague mentions but nothing concrete for UK setups
• Is there a way to temporarily override ESS priority without breaking everything
• Would adding a Zappi into the mix help here, or is that just adding complexity for the sake of it

Not looking for a full rewire, just want the thing to behave sensibly on a clear day rather than wasting generation.

Anyone else hit this wall? Curious whether it's a config issue or just a fundamental ESS limitation.

Has anyone checked whether ESS is throttling the inverter via the grid setpoint? I had something similar on my cabin setup where the Cerbo was effectively capping solar input because the grid setpoint was too conservative — it was "protecting" the grid connection rather than letting the MPPTs run flat out.

Worth checking in VRM:

• What's your ESS minimum SOC set to?
• Is DVCC enabled, and if so, what's your charge current limit showing?
• Are the MPPTs actually reporting full available power, or are they already being curtailed upstream?

Also, how many panels are you running and what's the array orientation? My van conversion taught me that even slight shading at certain times kills yield more than people expect. Could be the array itself rather than the ESS config.

@OddJobBob22 is onto something but I'd dig deeper into the ESS grid setpoint config first.

On the Cerbo GX go to: ESS → Grid setpoint — if that's set to something like 50W, the system is deliberately throttling solar input to avoid export. Classic symptom when you're on a non-export DNO agreement.

Also check your DVCC settings — specifically SVS, STS and BMS control. If you've got a Fogstar smart BMS talking to the Cerbo via CAN bus, it may be issuing charge current limits lower than you expect.

Run VictronConnect and pull the inverter history — look for any sustained #11 or #24 error codes.

What's your actual array size and MPPT model? I've got a similar MultiPlus-II setup on my narrowboat and the ESS tuning took me the best part of a fortnight to nail properly.

@OddJobBob22 and @ExSquaddie49 have nailed the ESS angle, so I'll add the bit nobody's mentioned yet — MPPT current limiting.

If your solar charge controller (which one are you running?) is undersized for your array, it'll clip output well before your panels' potential. Also worth checking in VRM whether your bulk/absorption voltage is being hit early, causing the MPPT to back off — common when Fogstar cells are already above ~52V.

Quick diagnostic: watch your MPPT output in real-time via the Cerbo dashboard while the EV is demanding power. If it's sitting at exactly 2kW and not budging, that's almost certainly a software ceiling (ESS grid setpoint or DVCC current limit). If it fluctuates around 2kW, you've got a hardware/sizing issue.

What's your array spec and which MPPT are you using?

Good shout from @OddJobBob22 and @ExSquaddie49 on the ESS grid setpoint — that's almost certainly your culprit.

One thing nobody's flagged yet: check your BMS communication with the Cerbo. If the Fogstar BMS is reporting a high state of charge or a charge current limit via CAN-bus/VE.Direct, the Cerbo will honour that and throttle everything — MPPT and inverter/charger alike — regardless of what your grid setpoint says.

In VRM, pull up the advanced tab and look at the "charge current limit (BMS)" parameter. If that's sitting suspiciously low (I've seen mine drop to 20A during warm spells), that's your 2kW ceiling right there.

Mine did exactly this last summer. Turned out the Fogstar BMS was derate-ing due to cell temperature. Worth ruling out before you dig further into ESS config.