Anyone else struggling to keep a 100Ah lithium topped up just on solar during a Scottish winter trip?

Just got back from two weeks up near Inverness and yeah, it's a proper battle. Running a 100Ah Fogstar Drift and had two 200W panels on the roof — thought that'd be plenty but the combination of short days, low sun angle, and seemingly endless overcast skies meant I was regularly only pulling 15-20% of rated capacity.

A few things that helped:

• Tilting one panel made a surprisingly big difference when the sun was actually out — even a shallow angle improvement helped
• Being brutal with consumption — killed the diesel heater fan speed, ran the fridge warmer than usual
• Shore power top-up where I could find it, even just a couple of hours at a campsite

The real issue is that in December Scotland, you've basically got 7 usable hours at best, and the sun barely clears the treeline. My Victron MPPT was showing pathetic numbers most mornings.

Honestly think if I did it again I'd either add a 40A DC-DC charger and keep the van running a bit each day, or just accept that a second 100Ah battery buys you buffer rather than fixes the underlying harvest problem.

What's everyone else doing? Anyone running a larger array up there or found a panel brand that handles diffuse light particularly well? I've heard some talk about monocrystalline performing better in low light but not sure if that's marketing or reality.

@FenlandVanLifer Scotland in winter is genuinely brutal for solar — you're looking at maybe 2-3 peak sun hours on a good day, often less. Two 200W panels sounds decent on paper but at that latitude in December/January you might only realistically harvest 200-400Wh daily even with a quality MPPT controller.

Key issues to consider:

• Panel angle matters enormously — a fixed roof mount at Scottish winter sun angles (sun barely gets above 15°) is losing you significant yield
• Fogstar Drift won't accept charge below ~5°C, so cold nights are killing your morning charge window
• A Victron SmartSolar with temperature compensation helps but can't fix physics

Honestly, for genuine Scottish winter off-grid you either need alternator charging via a B2B (Sterling or Victron Orion), a small genny, or accept you're managing consumption rather than truly topping up. What's your daily load actually running at?

@FenlandVanLifer yeah Scotland in December is basically a lost cause for solar-only, sorry to say it but it is 😅

Done similar up near Fort William in the van — even with a decent Victron MPPT squeezing every last watt out, you're just not getting enough hours. Panels were sitting at like 40W on a "bright" day.

What saved me was running the engine for 20-30 mins morning and evening, plus I'd added a B2B charger (Victron Orion) so it actually charges properly rather than dribbling in via the split charge relay.

Also — tilt your panels if you can. Low winter sun angle means flat roof panels are practically useless up there. Even a 30° tilt made a noticeable difference on mine.

100Ah is also on the small side for Scotland winter tbh. Could you add another battery?

@FenlandVanLifer 400W is actually a decent amount but Scottish winter will humble any setup. The issue isn't just the short days — it's the panel angle combined with low sun elevation. At Inverness latitude in December the sun barely gets above 10° above the horizon, so your roof-mounted panels are working at a severe disadvantage.

A tilting mount makes a massive difference in winter — I've seen 40-60% more yield just from angling panels properly. Worth considering if you're planning future trips north.

That said, I'd also look at your consumption. What are you actually running? If there's a diesel heater in the mix, that's manageable, but any resistive heating and you're fighting a losing battle regardless of panel count. Sometimes the honest answer is to supplement with a B2B charger from the engine rather than throwing more solar at the problem.

@FenlandVanLifer 400W in Scottish winter is basically decorative — I run my garden office on Victron kit and even here in a far friendlier latitude I've accepted that November through January is "the diesel genny months" rather than a solar victory parade. A Fogstar Drift is a cracking battery but it can't conjure photons that aren't there. Seriously consider a B2B charger wired to your alternator for those driving days — even an hour's motorway run will do more for your state of charge than a full Scottish "sunny" day. Renogy do a decent affordable one if you don't want to splash Victron prices.