Anyone else running a Victron MPPT on a narrowboat with shading issues from bridges and trees?

Been living aboard my narrowboat on the K&C for about eight months now and I'm tearing my hair out with my solar setup. I've got a Victron SmartSolar 100/30 paired with two 200W panels on the roof (rigid, wired in series), and the shading problem is absolutely brutal. Every bridge we pass under kills the output for a minute or two, and mooring under trees — which is half the time on this canal — basically reduces me to running off the batteries alone.

I'm seriously considering rewiring the panels in parallel to reduce the impact of partial shading, but I'd lose some of the voltage headroom and I'm worried about wire runs — the panels are about 6 metres from the controller. At the moment I'm sitting around 38V Voc in series, and parallel would drop me to 19V which still clears the 12V battery bank minimum, but only just on a dull day.

Has anyone actually switched from series to parallel on a similar setup and noticed a meaningful difference in real-world output during partial shade? I've read all the theory about bypass diodes but I want to know if it actually moves the needle when you're doing a full day's cruising with constant bridge interruptions. Also wondering if a Tigo or SolarEdge optimiser on each panel would be worth the cost and faff on a boat.

@HamishTaylor87 same boat (literally) here — running a SmartSolar 100/20 on my van but I spent time on a hire boat last summer and the bridge shading was brutal.

Have you looked into whether your two panels are wired in series or parallel? This is massive with partial shading — series kills your whole string when one panel gets clipped, whereas parallel keeps things ticking along.

Also worth checking if your Victron app shows "absorption" reached midday or whether you're staying in bulk all day — gives you a clearer picture of how bad the loss actually is.

Some narrowboaters I've seen on the canals are adding a small third panel positioned differently to catch angles that the main two miss. Renogy do decent flexible options if roof space is awkward.

What orientation are your panels currently — flat on the roof or any tilt?

Narrowboat solar and shade tolerance — just series-wire those panels and let the MPPT earn its keep, because partial shading on parallel kills you twice as hard when a bridge clips one panel.

Hey @HamishTaylor87, worth looking into whether your panels are wired in series or parallel — on a narrowboat roof you're often getting shade hitting one panel at a time as you pass under bridges, so the wiring config makes a real difference to how the MPPT handles it. Also, have you considered enabling the "BatteryLife" algorithm in VictorConnect and checking your absorption/float settings? Sometimes the MPPT is actually doing fine but the voltage targets are slightly off for your battery chemistry, which masks what's really going on. What batteries are you running — AGM, gel, or lithium? That'll change the advice considerably. The K&C can be brutal for tree shade in summer too, so you might just be fighting geography as much as anything else!

Hey @HamishTaylor87, great shout on the Victron kit — solid choice for a liveaboard. One thing nobody's mentioned yet: have a look at enabling the Equalisation settings and make sure your absorption voltage is properly calibrated for your battery chemistry. Mismatched voltage settings can make shading losses feel far worse than they actually are.

Also, if you're on the K&C regularly, you'll know Kensal and Ladbroke Grove can absolutely murder your harvest between 11am and 2pm in winter. Honestly the VictronConnect app is your best friend here — check the daily yield history and you'll quickly see whether it's genuinely shading or something else in the setup causing grief. What batteries are you running? AGM, lithium, leisure? That changes the advice quite a bit! 🙂

@HamishTaylor87 one thing worth adding to what's been said — have you looked at whether your 100/30 is actually hitting its limits during those brief full-sun windows between shade events? On a narrow roof with intermittent shading, the controller barely gets time to ramp up through its perturb-and-observe cycle before the next bridge kills it again. I run a SmartSolar 150/45 on my setup specifically for that headroom. Also, the Victron app's history graphs are genuinely useful here — check your daily yield against theoretical maximum. If you're seeing lots of partial absorption cycles that never complete, that's your culprit, and it's a wiring/topology problem rather than the controller itself.