MP2 does not charge with all available excess solar power

Been wrestling with something similar on my van setup, though scaled way down compared to some of the bigger residential installs I've been reading about.

Running a Multiplus II 48/3000 with a Cerbo GX and Fogstar Drift 48V battery. Solar goes through a Victron MPPT on the DC side, but the principle seems the same — the MP2 doesn't always pull the full available solar when it should.

What I've noticed:

• On a decent sunny day the MPPT shows plenty of headroom
• The MP2 stubbornly limits its charge current well below what's available
• This seems worse when the battery is above ~80% SOC

I think it's related to how ESS calculates the "target" charge current and doesn't always respond quickly enough to sudden solar availability changes. There's also something about the minimum SOC settings and feed-in permissions that can throttle things unexpectedly.

A few things I've tried:

1. Tweaking the ESS -> Optimise (with BatteryLife) settings
2. Adjusting the charge current limits in the DVCC menu
3. Checking whether the Cerbo firmware was current (it wasn't — updated helped slightly)

Still not convinced I've fully cracked it though. The VRM graphs show clear gaps between available PV and actual charge power that shouldn't be there.

Anyone else seen this, particularly with DC-coupled setups? I'm wondering if it behaves differently for those with AC-coupled solar on the input side versus DC through an MPPT. Would be curious whether larger systems with multiple batteries hit the same wall or if it's more pronounced at smaller scales.

@TransitCamper — did you get cut off there? Post got truncated, looks like it ends mid-sentence!

Curious what you're running alongside the MP2 though, because I've been scratching my head over something similar on my shepherd's hut setup. I've got a Multiplus II 48/5000 and noticed it wasn't pulling as much from the panels as I'd expected during the absorption phase — took me ages to realise the Max Charge Current setting in VEConfig was the culprit rather than anything exotic.

Also worth checking — is your AC Input Current Limit set appropriately? That can quietly throttle things in ways that aren't immediately obvious.

What MPPT are you pairing it with? And are you on ESS or standalone? Makes a big difference to how the MP2 handles excess solar priority.

@TransitCamper yes, looks like your post got chopped off — we're all hanging here wondering what you're running alongside that MP2!

That said, the issue you're hinting at is a classic one. The MP2's AC input current limit is often the culprit people overlook — if it's set too conservatively, the unit won't ramp up to absorb all available excess PV, even when your MPPT is screaming to offload it.

Worth checking in VictronConnect whether you've got the ESS Assistant properly configured, specifically the minimum SOC and feed-in excess solar settings. I chased my tail for a week on my cabin setup before realising the ESS grid setpoint was fighting against me.

Post the full setup details when you get a chance — PV array size, MPPT model, battery chemistry — and we can properly diagnose it.

@TransitCamper — looks like the forum ate the rest of your post, hopefully you can fill in the gaps.

In the meantime, a common culprit for this exact behaviour is the AC input current limit set too conservatively in VEConfig, which causes the MP2 to throttle charging even when excess PV is available. Also worth checking whether you have ESS Assistant loaded and whether the Minimum SOC and feed-in excess settings are configured correctly.

On my narrowboat setup I initially lost a significant chunk of available charge current because AC input limit was fighting the ESS logic. Dropping into VRM and watching the AC loads vs battery charge power graphs in real time made it obvious.

What does your DVCC configuration look like, and are you running a Cerbo or just USB-connected VEConnect locally? That'll narrow it down considerably.

@TransitCamper welcome to the forum, great to have another van person on here! 🚐

Looks like the post gremlins got ya — hoping you can edit and fill in the blanks, we're all curious what you're running alongside that MP2.

I've got a similar-ish setup in my motorhome (Victron kit throughout) and the ESS/charge current assistant config can be a real rabbit hole. Once you get your full post up I reckon between everyone here we can get to the bottom of it pretty quickly — there's some seriously knowledgeable folk on this forum.

Don't be shy either, no such thing as a daft question on here!

@TransitCamper while we wait for the rest of your post, I'll hazard a guess at what you're seeing — the MP2 has a PowerControl and PowerAssist interaction that trips people up constantly, particularly when you've got a MPPT feeding the DC bus simultaneously.

The classic symptom is the Multiplus throttling its charge current even though your MPPT is sitting at, say, 60% capacity. Worth checking your AC input current limit in VEConfig — that's often the culprit rather than anything solar-side.

Also, are you on the latest firmware? There were some known ESS assistant quirks pre-3.xx that caused exactly this behaviour on the 48/3000 specifically. Had similar headaches on my own 24V van build before I dug into VEConfig properly.

Drop the rest of your setup details when you can — MPPT model, battery chemistry, and whether you're running ESS or just standalone charging.