Anyone else's MPPT going haywire after the clocks changed?

My Victron SmartSolar 100/30 has been throwing absorption strops every evening like a teenager who missed tea — started right after the October switch.

Running 400W of panels on a 200Ah Fogstar lithium in the tiny house, and the thing's cutting out of bulk about an hour earlier than it should based on actual solar noon. Wondering if the internal clock's drifted or if the VictronConnect schedule is just being a plonker about BST→GMT.

Anyone cracked this one, or am I binning the afternoon charge before winter properly kicks in?

GeorgeSmith97 | 47 posts

@RetiredElectrician74 Classic one this — the SmartSolar uses the internal clock for its solar activity window, and when the clocks go back it essentially thinks sunset is happening an hour earlier than it should. Worth jumping into the VictronConnect app and checking the "Solar activity" times under the charger settings. Mine needed a manual nudge after October last year on my 75/15.

Also worth double-checking your absorption time settings — with Fogstar lithium you really want that kept fairly short anyway (I run mine at around 20 minutes). If the controller thinks it's later in the day than it is, it'll rush through bulk and trigger premature absorption warnings.

Should sort itself once you've synced the internal clock properly via Bluetooth. Let us know how you get on!

UC_Builds | 312 posts

@RetiredElectrician74 Worth checking whether the time zone in the VictronConnect app has actually updated properly — I've seen it stick on BST even after the clocks go back, which throws the absorption timing right out. Go into the SmartSolar settings and manually verify the system time rather than assuming the auto-sync sorted it.

Also, with Fogstar lithium you'll want to confirm your absorption end-trigger is set to current cutoff rather than time-based — if it's running time-based absorption and the sunset detection is miscalculating due to the clock issue, it'll keep attempting a full absorption cycle with barely any solar left to drive it. That's probably your "strop." Should settle down once the clock's corrected.

SolarNeil | 203 posts

Had exactly this with my shepherd's hut setup two Octobers running. The MPPT was triggering absorption an hour early because its internal clock hadn't shifted — meaning it was "seeing" the day end prematurely and panicking the charge cycle into overdrive.

What sorted it for me: go into VictronConnect, hit the three-dot menu on your SmartSolar, then Device Settings > System Setup and manually resync the time. Don't just trust it to pull the update automatically — mine never did.

@UC_Builds is on the right track about the time zone setting, but I'd also check whether adaptive absorption is enabled. When the clock's skewed and adaptive is on, the two compounds each other something rotten on shorter autumn days.

Worth doing before assuming the unit's actually faulty — mine's been rock solid since.