I've been mulling this over for months now. Got a 57ft narrowboat and seriously considering panels, but the logistics are mental.
The main issue is roof space—it's genuinely limited, and you're constantly shading yourself with the canal-side trees. I've done the maths with a mate who's got a 200W setup, and realistically you're looking at maybe 4-6 useful hours in summer, considerably less in winter. Not ideal for battery-heavy living.
That said, if you're moored up for extended periods rather than constantly cruising, it might be worth it as a supplementary system. The real win would be pairing it with a decent lithium battery bank—something like a Victron Smart LiFePO₄—rather than relying on engine charging alone. Engine hours add up quickly otherwise.
The physical installation side is doable but annoying. You need proper racking that won't leak, everything needs securing against movement, and you've still got the cable runs to sort through your narrowboat's existing wiring nightmare. Most installers either don't touch boats or charge premium rates.
I reckon the hassle-to-benefit ratio depends entirely on your cruising pattern and how long you're stationary. If you're on a residential mooring for half the year, absolutely crack on. If you're constantly moving through locks and under low bridges, probably not worth the grief.
Curious what others have actually done—is anyone running a proper setup that's genuinely making a difference? Or is everyone just using them as a supplement?