Anyone else running a Victron Multiplus with a SmartSolar MPPT on the same system — how are you handling charge priority?

Just got my Multiplus-II 24/3000 wired up alongside a 100/30 SmartSolar, feeding a 200Ah lithium bank. Everything's talking nicely over VE.Direct and I've got the Cerbo GX pulling it all together. On paper it looks great, but I'm second-guessing my charge settings now that both the inverter/charger and the MPPT are trying to bulk at the same time when I'm plugged into shore power.

At the moment I've got the MPPT set to 28.8V absorption and the Multiplus bulk/absorb at the same voltage, figuring they'd just share the load naturally. But I've noticed the MPPT occasionally seems to back off earlier than I'd expect — not sure if that's the DVCC kicking in and limiting it, or if my wiring sequence is causing a slight voltage difference at the battery terminals. Total charge current ceiling is set to 60A in the DVCC settings on the Cerbo.

Has anyone run into the same sort of thing? I'm wondering whether it's better to let DVCC do all the talking and just set one master charge profile, or if there's a reason to keep the MPPT's own profile active as a fallback. Happy to share my full config if that helps narrow it down.

RachelLamb | 47 posts

@DailyProject Nice setup! One thing worth doing if you haven't already — enable the DVCC (Distributed Voltage and Current Control) on your Cerbo. It hands charge coordination over to the GX device so the Multiplus and MPPT aren't accidentally fighting each other for control. With lithium especially, you really want a single charge authority rather than both units making independent decisions.

Also set your SVS (Shared Voltage Sense) and SCS (Shared Current Sense) whilst you're in there. Makes a noticeable difference to charge accuracy across the system.

What BMS are you running on the lithium bank? If it's got a VE.Bus or CAN connection, you can get the Cerbo talking directly to it and the whole system becomes genuinely clever about charge limiting. Changes everything.

Trigger | 312 posts

@DailyProject Worth being precise about your charge profile once DVCC is sorted. With lithium you really want the Multiplus AC charger and the MPPT working to the same absorption voltage rather than fighting each other — the Cerbo becomes the single point of truth for that under DVCC, which is the whole point of the architecture.

On my shepherd's hut system (24V, Fogstar Drift 200Ah), I set a fixed absorption voltage of 28.4V with a fairly short absorption time, then let the SmartSolar handle the tail current monitoring. The Multiplus just follows whatever the Cerbo hands down.

One thing people miss — make sure your battery's own BMS is configured to communicate if it supports VE.CAN or VE.Direct. If the BMS can talk directly to the Cerbo, that takes priority over everything else for charge limits, which is far safer.

Holly1960 | 203 posts

Great setup @DailyProject! One thing I'd add to what @RachelLamb and @Trigger are getting at — once you've got DVCC dialled in and your charge profile sorted, have a look at the ESS assistant if you're also grid-tied. It changes how the Multiplus handles priority quite significantly.

Also worth checking your VE.Configure settings for the Multiplus aren't fighting against what the Cerbo is trying to do via DVCC — I had a right headache early on because my manually configured absorption voltage in VE.Configure was slightly different to what I'd set in the Cerbo. They need to match or DVCC can behave oddly.

What BMS are you running? That can affect how much control you actually hand over to the Cerbo for charge management.