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

Living on the cut means my panels are constantly getting partial shade — overhanging trees, low bridges, the boat next to me at a mooring. I've got two 200W Renogy panels wired in series on the roof and the voltage drop when even one panel catches shade is brutal. Thinking it might be time to rewire in parallel or look at MPPT optimisers.

Currently running a Victron SmartSolar 100/30 which handles the MPPT side well enough, but I'm losing probably 30–40% of my potential harvest on cloudy or tree-heavy days. The boat's main bank is 200Ah of Battle Born LiFePO4 so it handles partial charging fine, it's just the solar input that's the bottleneck.

Has anyone switched from series to parallel on a narrowboat setup and actually seen measurable gains? Or gone down the optimiser route — SolarEdge, Tigo, that sort of thing? Curious whether the faff and cost is worth it given the relatively small system size.

@Jess1989 Series wiring is your enemy with partial shade — one shaded cell drags the whole string down. Had the exact same problem on my boat before I switched to parallel wiring with individual fuses. Immediate improvement.

Worth considering whether your controller handles this well too — MPPT will cope better than PWM, but even a decent MPPT struggles when panels are mismatched in output.

Have you looked at adding bypass diodes to your panels? Some Renogy units already have them built in, but worth checking the spec sheet.

If you're regularly mooring under trees, you might also consider whether splitting into smaller individual panels wired in parallel gives you better resilience — each panel becomes independent so patchy shade doesn't kill your whole array.

What controller are you running currently?

@Jess1989 Been through this on my own boat. Beyond what @12V_King said about series wiring, seriously look into individual panel-level optimisers or just go full parallel if your cable runs allow it.

The other thing that made a massive difference for me was a Victron SmartSolar MPPT — the algorithm handles partial shade noticeably better than cheaper controllers. Worth the extra outlay.

Also worth considering: on the cut you're often moored at awkward angles relative to the sun. Tiltable mounting brackets helped me squeeze more out of mornings and evenings when the trees are worst.

Realistically you'll never fully solve it — it's just part of liveaboard life. Manage your consumption expectations on gloomy tree-lined stretches and let the controller do its best.

What @12V_King and @KevWatson57 said about series vs parallel is spot on, but one thing I'd add from my own static caravan setup — bypass diodes only partially mitigate the issue, they don't eliminate it.

Worth looking at whether your charge controller is MPPT rather than PWM, because with shading scenarios the MPPT algorithm matters enormously. Some cheaper units struggle to find the actual global maximum power point when there are multiple local peaks on the IV curve.

Victron's SmartSolar range handles this noticeably better in my experience — the panel layout software (VictronConnect) also lets you monitor string performance which helps diagnose where the shading losses are worst throughout the day.

Also — have you considered the panel angle? Flat-mounted on a narrowboat roof versus a slight tilt could meaningfully affect how quickly shade clears across the cell surface.

Parallel wiring and individual MPPTs are already covered well by the others, but one thing worth adding from my narrowboat experience — panel placement matters more than you'd think.

I repositioned one of my panels to the stern where it catches morning sun before the trees get in the way, rather than having both panels clustered amidships. Even small gains in unshaded hours add up across a week.

Also, if you haven't already, check whether Renogy's bypass diodes are actually functioning properly. Had a dodgy one on mine that was making shading far worse than it should've been — easy enough to test with a multimeter.

Victron's MPPT Connect app is useful for spotting exactly when and how badly you're losing harvest throughout the day, which helps you figure out whether it's a wiring, positioning, or hardware problem.

If shading's your nemesis, a Tigo optimiser on each panel is like giving them individual counselling — my shepherds hut setup laughed off a massive oak tree once I fitted them, and the narrowboat lot swear by them on the cut for exactly this chaos.