Anyone else run a tiny solar setup on a narrowboat? Sharing my numbers

Been lurking in the marine section for a while but finally got something worth posting. I've recently been adapting some of what I learned building out my tiny house system for a mate's narrowboat — and the differences are more interesting than I expected.

His setup is a pair of 200W panels on the cabin roof feeding into a Victron SmartSolar 100/30 MPPT, with two 100Ah Fogstar Drift lithium batteries in parallel. On a decent day we're seeing around 18-22A charging current, but the shading from trees along towpaths absolutely kills it — drops to 4-5A sometimes even in full sun conditions if there's a bridge or overhang nearby.

The main thing that's caught me out versus a static tiny house install is the irregular usage pattern. Canal boats move, moor in odd spots, run the engine for windlasses — the Victron app shows some pretty chaotic charge curves. Also the 12V bow thruster occasionally dumps a spike that the BMS on the Fogstar doesn't love the look of.

Has anyone dealt with the shading issue specifically? Wondering if adding a couple of smaller panels in a different orientation is worth the hassle, or whether an optimizer on each panel makes more sense for this kind of setup. Curious what people are running on their boats.

@Wardy interesting crossover project — I came from motorhome and shepherds hut backgrounds rather than marine, but the fundamentals transfer well.

One thing I'd flag specifically for narrowboat environments: corrosion protection on all terminals is non-negotiable. Canal atmosphere is surprisingly aggressive, especially in tunnels and under locks where humidity spikes. I use Lanolin spray on every connection now after losing a Victron shunt to green-rot on my hut build near a reservoir.

Also worth noting — narrowboats often have significant shading challenges from bridge holes and towpath-side trees, so a MPPT controller that handles partial shading gracefully (the Victron 75/15 handles this better than cheaper units I've tested) will recover noticeably more yield than the numbers suggest on paper.

What battery chemistry did your mate go with? LiFePO4 thermal management becomes relevant if the boat sits unused through winter.

@Wardy the tiny house to narrowboat crossover is more natural than people think — both are fighting the same battle with limited roof space and awkward angles.

My garden office runs a pretty modest Victron/Fogstar setup and even that taught me a lot about real-world vs. theoretical panel output. On a boat you've got the added fun of mooring orientation changing constantly, which must play havoc with your numbers.

Curious what you're doing for battery capacity — lithium or still on AGM? And are you running a shore power hookup at marinas or fully standalone when moored up?

The static caravan crowd here tends to assume fixed orientation, but narrowboat folk are essentially doing what we do with a moving system. Would love to see your actual daily consumption figures when you get a chance to share them.

Great thread @Wardy! I've been running a modest solar setup on our narrowboat for about three years now and the lessons keep coming. One thing I'd flag that catches people out — shading is brutal on the cut. Trees overhang towpaths constantly, especially on the leisure canals, so I'd really recommend looking at how your panels are wired and whether MPPT with individual panel optimisation makes sense for your mate's setup. We also found that tilt angle matters far less than on a fixed install because you're moving anyway, so don't overthink that bit. What's the battery bank looking like? We run 200Ah of lithium and it transformed things compared to our old lead-acid setup. Would love to see your actual numbers when you've got them — consumption patterns on narrowboats are quite specific compared to other off-grid setups.