Does anyone actually get useful output from a 200W panel in a UK winter?

I've had a single 200W mono panel on the roof of my narrowboat since last March and through summer it was brilliant — regularly hitting 150W+ on a clear day and keeping my 100Ah lithium topped up no bother. But now we're into December and I'm lucky if I'm seeing 20–30W peak, and that's only for a couple of hours around midday. Running it through a Victron 75/15 MPPT if that makes any difference.

I get that the sun angle is lower and the days are shorter, but I wasn't quite expecting it to be this bad. I'm moored up in the East Midlands, panel is south-facing and mostly unshaded. My daily consumption is roughly 40–50Ah (LED lighting, a 12V compressor fridge, phone charging, occasional laptop). So at the moment I'm basically just topping up with a hook-up whenever I can or running the engine.

Has anyone found a practical way to improve winter output short of adding more panels — tilt frames, different panel types, anything? Or is the honest answer just that solar doesn't really cut it on a UK boat in winter and you need a decent backup sorted?

WattAMess27 | 847 posts

@BoatShaun Honest answer — yes, but you need to massively adjust your expectations. My 200W panel in December/January is doing well to produce 20-40Wh on a decent day, sometimes barely anything for days on end when it's just grey soup outside. The saving grace on a narrowboat is you're moving — even motoring an hour charges more than the panel will manage all day in midwinter.

Worth checking your panel angle too. A fixed flat roof mount that's great in summer is losing you a significant chunk of output in winter when the sun sits low. Even propping it up temporarily at 60-70° makes a noticeable difference on the rare sunny days.

I'd plan around the engine doing the heavy lifting November through February and treat any solar as a bonus.

DebbieTaylor | 1,203 posts

@BoatShaun Worth keeping an eye on your panel angle through winter — on a narrowboat you're obviously limited, but even propping a portable panel at 60-70° rather than lying flat can make a noticeable difference when the sun stays low. I've got 400W on my static cabin in Derbyshire and December/January I'm realistically budgeting on 2-3 good hours of usable generation per day, often less. That 200W might realistically give you 20-40Wh on a gloomy day, occasionally touching 100Wh if you catch a crisp sunny afternoon. Plan your consumption around it rather than assuming it'll keep pace with summer habits. LED lighting, a decent 12V blanket instead of a fan heater, and timing any heavier loads for midday genuinely helps stretch what little you get. It's not hopeless, just requires more discipline!