Anyone else finding their van setup completely useless in a Scottish winter?

Spent the weekend up near Loch Lomond and my 200W Renogy panel produced an embarrassing 15–20Wh on the Saturday. Solid overcast, sun barely clearing the treeline, and the angle was all wrong since I'm roof-mounted flat. Running a 12V compressor fridge plus a bit of phone charging basically flattened my 100Ah Fogstar lithium overnight.

I'm wondering whether it's even worth the hassle of chasing solar in December/January up here, or whether I should just accept that a decent shore power hookup or a DC-DC charger from the alternator is the realistic answer for winter months. Anyone running a dual-input setup — solar and alternator charging — finding the alternator does most of the heavy lifting from October through to March?

Also curious whether tilting the panel makes a meaningful difference in low-sun conditions, or whether the diffuse light issue just swamps any gain from better angle. Feels like I'd be faffing with a tilt kit for marginal gains when the sky is just a grey blanket anyway.

DaleBen | 847 posts

@MuddyRanger Aye, Scotland in winter is genuinely humbling for solar. 15-20Wh from 200W is about right for a flat-mounted panel under heavy overcast up there - you're essentially running on diffuse light only.

Couple of things that helped me last January on the NC500: I added a small tilt bracket so I could angle the panel manually when parked up, made a noticeable difference even on grey days. More importantly though, I stopped relying on solar as my primary input between November and March. Either a DC-DC charger from the engine or a decent hook-up when available.

Scottish winters are really a case of managing consumption rather than chasing generation. What's your battery capacity? Sometimes the problem feels like a solar issue but it's actually just undersized storage for the loads you're running.

RussWilson | 312 posts

@MuddyRanger Scotland in winter is basically solar's kryptonite, sadly. What's saving me is having a decent split-charge relay setup so any driving at all is actually topping the battery up meaningfully. Even a 45-minute drive to reposition gives me far more than a full day of panels up there.

Also worth looking at a small wind turbine if you're regularly in exposed spots - Loch Lomond certainly isn't short of a breeze. A 400W wind unit will absolutely trounce solar output from October through March in Scotland.

Short term though - have you looked at adjusting your panel angle manually? Even propping the front edge up with a bit of timber to chase whatever weak sun does appear can make a noticeable difference on partially cloudy days.

DodgyNomad | 1,203 posts

@MuddyRanger Worth having a serious think about a B2B charger if you're doing regular Scottish trips — keeping it topped up whilst driving makes a massive difference when the panels are basically decorative. I'd also look at whether you can tilt that panel even slightly; even propping the leading edge up 20-30° on a flat roof can squeeze noticeably more out of low winter sun at those latitudes. The angle thing is genuinely underrated up there. Also, what's your actual consumption looking like? Sometimes tightening that up buys you more breathing room than chasing generation. A small 12V blanket instead of a diesel heater for sleeping, for instance, can shift your whole energy budget considerably.

MoreTeaVicar | 634 posts

Static caravan rather than a van, but I faced the exact same reckoning last December. What turned things around for me was getting properly obsessive about panel angle — I've got mine on a adjustable mount now, cranked up to about 60° through the dark months. Scotland's low sun elevation means your flat-roof van install is essentially presenting a polished surface to the sky rather than catching photons.

The honest truth though? From roughly November to February I've mentally written off solar as supplementary at best and sized my battery bank accordingly — 200Ah Fogstar Drift cells — to just ride out three or four grim days without stressing. Tilt what you can, store what you can, and stop expecting June performance in January. The maths just doesn't work up here.

BurnJim | 2,156 posts

@MuddyRanger Those numbers are genuinely grim but honestly pretty typical for central Scotland in December/January. Worth noting that panel angle makes a massive difference when the sun's so low — even just propping the front edge up 20-30 degrees can nearly double your harvest on those rare bright days.

What's your battery capacity and what are you actually running? Sometimes the answer isn't more generation but trimming consumption ruthlessly. I switched to a 12V diesel heater and LED everything, which meant my existing setup stretched much further between charges.

@DodgyNomad is right about the B2B too — if you're moving at all, your alternator becomes your primary source up there in winter, full stop. Solar is basically a bonus from November through February. Plan around that reality and you'll stop feeling so defeated by it.