Does anyone actually get useful winter solar from a 200W panel on a south-facing van roof?

I've been running a 200W mono panel (a Renogy one, bolted flat on the roof) since last spring and through summer it was brilliant — regularly seeing 8–10A into my 100Ah lithium on decent days. But now we're into November I'm lucky to see 2–3A even on a clear day, and by 3pm it's basically done. I knew winter would be worse but this feels pretty dire.

I'm parked up in the Peak District most of the time, so not exactly Cornwall. The panel is flat-mounted, which I know isn't ideal for low sun angles. I've seen people talk about tilting brackets but I'm not sure how much difference that actually makes at, say, 52° north in December.

Has anyone done a proper before/after with tilted vs flat mounting at UK latitudes? I'm wondering whether it's even worth the hassle and the wind noise, or whether I should just accept winter solar is rubbish here and rely more on my B2B charger when I'm driving. My van trips are usually 3–4 days at a stretch so I do need something reliable.

@DustyHiker the flat mounting is absolutely killing you in winter. I've got a 200W Victron panel on my static caravan roof — same deal, fixed flat — and December/January I'm lucky to see 2–3A on a clear day. Sun angle in the UK at winter solstice is barely 15° above the horizon even at noon. Your panel wants to be tilted at roughly 50–55° to catch it properly.

The other thing nobody mentions: low-angle sun means longer atmospheric path length, so you're losing more to scattering even on "clear" days.

Realistically with flat mounting, budget for 10–20% of your rated summer output through December. That's maybe 20–40Wh on a good day. Fine if you've got 100Ah lithium with modest loads, genuinely useless if you're running a compressor fridge. What are your actual daily consumption figures?

@DustyHiker I'll give you an honest answer from bitter experience — last January at my static caravan in the Midlands, my flat-mounted 200W pulled barely enough to keep my Fogstar 100Ah ticked over, let alone charge it meaningfully. We're talking 1–2A on a grey afternoon.

What actually saved me was accepting winter solar as supplementary, not primary. I added a small generator for proper bulk charging every few days and let the panel handle float maintenance in between.

The maths are brutal — December sun angle plus frequent overcast plus shorter days means your 200W panel is performing more like a 40–50W panel in practice. Don't size your expectations against the nameplate rating.

If emergency backup is your concern (same as mine), plan your system assuming zero solar input for days at a stretch. Anything you harvest is a bonus.

@DustyHiker I've been doing exactly this for three winters now with my motorhome parked up in Yorkshire. Flat-mounted 200W Renogy, same as yours. December and January are genuinely humbling — some days I'm getting barely 2–3A at peak, and that's only around midday for a couple of hours.

What saved my sanity was accepting it early and adjusting expectations rather than chasing more panels. I run my Fogstar 100Ah lithium down no further than 50%, keep a small mains hookup trickle charger ready at static sites, and do my heavy loads (kettle, hair dryer) only when I'm plugged in.

The solar in winter is maintenance, not generation. Once I reframed it that way, winter stops feeling like a failure.

Just to add some numbers to what @FormerTeacher is getting at — I ran a similar 200W Renogy flat on my Transit last winter and was lucky to see 2–3A on a grey December day in Yorkshire. Moved up to Scotland for a few weeks and it was genuinely embarrassing.

Two things that actually helped me: first, parking with the side of the van facing south when stationary so you can lean a portable panel against it at a better angle. Second, being really ruthless about your loads — winter's the time to audit everything. LED lighting, a decent sleeping bag instead of running a heater, that sort of thing.

100Ah lithium should cope if you're not draining it heavily overnight. What's your rough daily consumption looking like? That'd help figure out whether you need more panel or just better habits.

Hey @DustyHiker — worth mentioning something nobody's touched on yet: angle really matters in winter. At 51°N+ the sun barely gets above 15–20° at noon in December, so a flat roof panel is working at a serious disadvantage compared to summer. If you can prop yours up even temporarily when parked — some people use a simple tilting bracket or just lean it against the van — you'll genuinely notice the difference. I knocked together a basic adjustable mount for about £15 in parts from B&Q and it made a noticeable improvement on my setup over January. Obviously not practical while driving, but if you're stationary for a few days it's worth the faff.

Great thread this. @DustyHiker to give you a practical figure from my own experience — I've got a 200W panel flat on a Sprinter and in December/January around the Midlands I'm typically seeing 2–4A on a clear day, maybe peaking briefly around noon. Cloudy days you're lucky to see 1A sustained. It's not nothing, but it won't keep a fridge running comfortably without shore power or a leisure battery top-up from driving.

What I'd suggest: don't rely on solar alone through winter. Factor in your alternator charging as part of the system rather than a backup. The solar becomes more of a trickle maintenance charge than a primary source from November through February, and there's no shame in accepting that. Plan your consumption accordingly and you won't be disappointed.

Good points all round here. One thing I'd add — cloud type matters massively in winter. A thin overcast can still give you a surprisingly decent harvest, whereas thick grey stratocumulus (basically the British winter default) genuinely kills output. I tracked mine on a Kill-a-Watt equivalent last January and found I was getting decent-ish days maybe 4-5 times per month rather than being completely starved. So it's not useless, but I'd second what others are saying — don't rely on it as your only source. A small backup charger from your alternator while driving is worth its weight in winter months.