Solarregel taktet im 10 Minuten Rhytmus

Anyone else had their MPPT controller start cycling on and off in a weird rhythm?

Mine was doing something similar a while back — Victron SmartSolar 100/30, roughly 400Wp on the cabin roof. Every 10-15 minutes it would just... drop out, then kick back in. Drove me absolutely mad trying to figure it out.

Turned out it was a combination of things:

• Battery absorption threshold — once it hits that voltage it throttles right back, can look like cycling if you're not watching Victron Connect closely enough
• Temperature compensation going a bit haywire (my BMS was sending dodgy temp data)
• Loose MC4 connector on one of the panels — intermittent, obviously the worst kind

The absorption one catches people out a lot tbh. On a smallish bank it can look like the controller's misbehaving when really it's just... doing its job. Annoyingly.

Worth checking:

1. What charge stage is it actually in when it cycles? (VictronConnect history tab)
2. Any partial shading? Even a little can make MPPT do odd things
3. Check your tail current settings if you're on a Fogstar or similar LiFePO4

Also — is it genuinely 10 minutes like clockwork, or just roughly 10 minutes? Clockwork suggests something deliberate in the firmware. Rough cycling is more likely environmental.

Curious if anyone else has seen this pattern, especially through winter when the irradiance is all over the place. UK weather makes diagnosing solar faults properly painful.

Mine did exactly this with my SmartSolar 75/15 on the motorhome — turned out the battery voltage was sitting right on the absorption threshold and the controller kept second-guessing itself like a confused locum doctor. 🙄

Check your absorption voltage setting — if it's too close to your resting voltage, the MPPT goes into this maddening on/off dance thinking the battery's full when it jolly well isn't.

Also worth checking:

• Wire gauge — voltage drop can trick the controller
• Battery temp compensation — especially now it's cold
• Are you on AGM or lithium? Settings matter enormously

@EcoFlow_Gal what does your VictronConnect app show for battery voltage during the cycling? That'll tell us everything.

Worth checking your absorption setpoint if you haven't already. If it's set too low for your battery chemistry, the controller hits absorption, backs off, voltage drops, and it starts the whole cycle again — classic float hunting behaviour.

Also worth looking at your cable runs. Undersized or corroded connections can cause enough voltage drop to confuse the MPPT into thinking it's done charging when it hasn't. I had a dodgy Anderson connector on my setup doing exactly this — Victron VictronConnect app showed perfectly normal behaviour on paper but the rhythm gave it away.

What battery type are you running? If it's a lithium (Fogstar or similar) with its own BMS, the BMS cutting in and out could be the culprit rather than the MPPT itself.

Ah, the classic MPPT disco mode — your controller's auditioning for a DJ set nobody asked for 🎛️

Had this exact faff on Perseverance (my narrowboat) last summer. Turned out my Victron SmartSolar was basically arguing with itself over whether the Fogstar lithium pack was full or not.

Got a garden office setup with a SmartSolar 100/20 and had something similar last spring. One thing nobody's mentioned yet — are you running lithium or lead-acid?

With my Fogstar Drift cells I found the BMS was occasionally tripping and recovering, which looked identical to MPPT cycling from the outside. The controller wasn't the issue at all.

Worth checking whether the cycling correlates with a specific SOC level. Mine was consistently happening around 95-98% — BMS doing its balancing thing and briefly disconnecting the load side.

@HazelPaddy makes a good point about absorption setpoints, but I'd rule out the battery/BMS side first before adjusting anything in the Victron app. Easy enough to check via the VictronConnect history — does it log any error codes during the cycling periods?