Smartsolar MPPT

Running three Victron SmartSolar MPPT 100/20s networked together in my garden office setup, and I've just discovered they've apparently been having a little committee meeting about who gets to do the least work.

Two are handling the roof panels and one's on a portable folding array I wheel out when the British weather occasionally remembers the sun exists — all linked via VE.Smart Networking so they share voltage sense and temperature data like a proper little socialist collective.

The problem? When I check the Victron Connect app, the absorption and float transitions aren't happening in sync the way I'd expect. The portable panel controller seems to march to the beat of its own drum, drifting slightly out of phase with the other two. Doesn't seem to be catastrophically wrong, but it's not the seamless handholding Victron's marketing photos suggested.

Few questions for the hive mind:

• Anyone else running multiple SmartSolars networked together on a UK install?
• Is the VE.Smart sync actually reliable in practice, or is it more of a "near enough is good enough" situation?
• Would a Cerbo GX tighten things up, or is that just buying more kit to solve a problem I've created myself?

Fogstar cells in the battery bank if that's relevant — 280Ah of prismatic goodness sitting there wondering why its charging masters can't get their act together.

Genuinely love the Victron ecosystem but sometimes it feels like you need a degree in electrical engineering just to validate that everything's working as advertised — or is that just me?

@JackShaw yeah that's the VE.Smart Networking doing its thing — one unit gets elected as the "master" and coordinates charge state across all three. It's by design rather than a bug tbh.

Worth checking in the Victron Connect app which one's acting as master and whether your battery voltage sense is set correctly on that unit. If the master's reading slightly off, the others just follow it blindly.

Had similar on my tiny house build with two 100/30s — turned out I hadn't enabled shared voltage sense properly so they were working from slightly different references.

Make sure shared voltage sense and shared temperature sense are both ticked on all three units. Sorts it right out.

@JackShaw had exactly this in my van build — three MPPTs squabbling over the throne like some sort of solar monarchy. What I found useful was checking the VictronConnect app during peak sun hours and watching which unit consistently wins the election; it's usually the one seeing the strongest panel input.

Worth knowing: if you're not happy with who's been crowned master, you can temporarily disconnect the others from VE.Smart, let your preferred unit establish itself, then reconnect. Bit fiddly but it works.

The real question is whether your absorption and float voltages are syncing properly across all three — that's where the committee metaphor actually matters. If one rogue unit decides to do its own thing on voltage, your battery's going to have a rough time.

What battery chemistry are you running?

@JackShaw so what actually happens if you pull the master out of the network mid-charge? Does the whole thing throw a wobbly or does one of the others step up and seize power like a very boring coup?

Asking because I'm planning something similar for my shepherd's hut — three panels on different roof pitches so I figured multiple MPPTs made sense, but I hadn't really considered the political implications of networked charge controllers having opinions about hierarchy.

Do you find the load gets shared sensibly between all three units, or does the newly-crowned master just sit there barking orders while the others do all the actual work?

@Slim pulled that exact stunt during a Fogstar battery commissioning job last year — yanked the master MPPT offline to swap a fuse and held my breath waiting for fireworks.

Anticlimactic answer: the remaining units just elect a new master within a few seconds and carry on like nothing happened. It's surprisingly graceful for a bit of kit that costs less than a weekend in a Premier Inn.

The interesting bit is that brief window during re-election — if you're watching VictronConnect you'll see the charge current dip momentarily while they sort themselves out. On a big array that dip is actually visible on your battery monitor. Completely harmless, but oddly satisfying to watch, like seeing a village fête committee suddenly reorganise after the chairperson nips off for a scone.