Solar panels on a narrowboat – does anyone actually get decent charge on the move?

I've been running solar on my narrowboat for three years now, and I'll be honest — it's more supplementary than game-changing when you're moving regularly.

I've got 400W of rigid panels on the roof (two Renogy 200W units), and whilst they work brilliantly in summer when stationary, the reality of continuous cruising is different. The angle degrades significantly unless you're heading due south, and you lose efficiency through cloud cover, dust, and water spray. On a typical cruise day, I'm getting maybe 30-40% of rated capacity if I'm lucky.

That said, it's still worth doing. The panels offset my fridge and water pump draw, which reduces my battery discharge and means I'm not starting each evening already depleted. I pair them with a decent MPPT controller (Victron SmartSolar 100/50) and a 200Ah LiFePO₄ bank — without both, you won't see worthwhile gains.

The real problem is that most boaters rely on engine charging anyway when moving, so solar becomes redundant during cruising hours. It makes more sense if you're planning to wild moor or use shore power regularly. During the summer months stationary, I can genuinely run 24/7 off solar alone, which is satisfying.

My honest take? Install it if you want, but don't expect it to replace engine charging on a working narrowboat. Budget for lithium batteries and a solid MPPT setup instead — that's where the actual gains come from.

What's your cruising pattern? Continuous or mostly stationary?

I'm curious what angle you're running those panels at when moored vs moving? I've been looking at solar for my van conversion and keep hearing the same thing — decent charge only really happens when you're stationary and the panels are optimally positioned.

Are you finding the rigid panels better than flexible ones for a narrowboat, or is it just what worked for your setup? I'm wondering if the constant shading from banks and locks makes a real difference to your output figures.

Also, what battery capacity are you working with? Seems like the mismatch between peak solar potential and actual usage might be the real issue rather than the panels themselves.

The angle question @EwanChapman raises is spot on, but honestly, I reckon the real killer on a boat is the constant shadow problem. You're either under a bridge, passing trees, or moored next to someone else's wide beam blocking the sun entirely.

I've got 300W on my narrowboat and treat it as a "nice to have" rather than load-bearing. The days I actually get decent charge are the sunny mooring days — which in UK waters aren't exactly thick on the ground, are they?

@RetiredSquaddie's right about it being supplementary. That said, rigid panels hold up better to condensation and foot traffic than flexible ones, so there's that. But if you're moving regularly, you're fighting a losing battle against cloud cover and shadows. Better off upgrading your shore power setup and carrying a decent generator backup.

Yeah, the angle thing's crucial but honestly the shading is the real killer on narrowboats. Trees, bridges, other boats moored up — it's relentless.

I've got 200W on my narrowboat setup paired with a Victron MPPT, and I'm realistic about it. On a sunny moving day in summer? Maybe 80-100W actual output. The panels are permanently mounted at about 15° which is rubbish for UK latitude but necessary for headroom.

What actually saved me was accepting solar does the maintenance charging — topping up your lithium when you're stationary for a few days. Not the heavy lifting. My leisure battery bank handles the actual load, then the diesel engine kicks in when needed.

If you're moving regularly, pair your solar with shore power when available and solid battery capacity. Solar alone on a boat in the UK is a false economy IMO.

What about tilt brackets or adjustable mounts? I've been pondering this for my setup too, and it seems like fixed panels are fighting an uphill battle when you're constantly repositioning through locks and moorings.

The angle thing @EwanChapman mentioned — have you lot considered seasonal adjustments at least? Even manually angling them differently between summer and winter could shift your output quite a bit.

Also curious whether anyone's experimented with flexible panels along the gunwales instead of rigid roof-mounted ones? I'm wondering if that might help you work around the shading issue @PanelKate's describing. Bridges and tree cover would still be a problem, but you'd at least have some flexibility in placement.

What's your average daily generation looking like currently, @RetiredSquaddie? That'd help me figure out whether it's even worth the hassle on my boat.

Tilt brackets are a rabbit hole, mate. I looked at them seriously — the extra weight on a narrowboat roof is genuinely problematic for stability and mooring dynamics, especially in any wind. Plus they're theft magnets at popular spots.

The real issue nobody mentions: even if you nail the angle, a 400W array on a boat realistically sees maybe 60-70% of its rated output when moving through the system. You're constantly in transit shadows, and your battery charge controller can't optimise properly with that inconsistent input.

What actually works is accepting solar as a trickle on the move — maybe 15-20A on a good day — and planning accordingly. I charge aggressively at marinas with shore power instead. Shifted my mentality from "solar will keep me off-grid" to "solar tops up my battery bank between proper charges."

If you're serious about autonomy, look at your consumption first. That's where the wins are.

Been there with the tilt bracket dilemma. I learned the hard way that narrowboat roofs aren't designed for mucking about—every extra weight affects stability and mooring stress. Added 40kg of adjustable gear to my setup, and within two seasons the vibration from movement had loosened everything requiring constant maintenance.

What actually worked for me was repositioning my 300W array during winter months when I'm stationary longer. Took maybe ten minutes with a cordless drill and some angle iron offcuts. Summer, I accepted the supplementary role and beefed up my backup—added a second Victron MPPT and expanded my lithium bank instead.

The real gains came from managing expectations and battery capacity, not chasing perfect panel angles. My Honda EU22i now rarely kicks in, which was the actual goal. Sometimes it's better to store more than generate more on a moving platform.