Anyone else struggling to get decent solar output through a UK winter? Sharing my setup and numbers

So I've been running a 400W panel array on my static caravan up in the Peak District since last spring and the drop-off in December has been genuinely shocking. We're talking maybe 200–400Wh on a clear day versus the 1.8–2kWh I was regularly pulling in back in June. I've got a Victron SmartSolar 100/30 MPPT going into two 100Ah AGM batteries, and even with conservative loads (LED lighting, a 12V fridge, phone charging) I'm regularly hitting the low voltage cutoff by mid-afternoon.

I'm wondering whether panel angle is part of my problem. I've got them mounted flat on the roof at roughly 5–10° just for drainage, which I know is far from ideal in winter. At 53° north the optimal tilt apparently jumps to something like 65–70° in December. Has anyone actually bothered to remount or build a tilt frame for winter, and did it make a meaningful real-world difference? I've seen some rough calculations suggesting it could nearly double output on sunny days but I'd love to hear actual experiences rather than theory.

Also genuinely curious whether anyone has added a small wind turbine as a complement for the grim grey days when solar is basically useless. A neighbour up here runs a 400W Rutland and swears by it, but I've read mixed things about noise and maintenance. Is it worth the hassle for a semi-rural site, or should I just bite the bullet and get a small petrol genny for backup?

Del58 | 847 posts

@Mike1986 those December numbers are actually pretty reasonable for your latitude if I'm honest! Peak District you're looking at maybe 1-1.5 peak sun hours on a clear winter day, so 400Wh from a 400W array isn't far off theoretical best.

Few things that made a genuine difference for me up in Cumbria:

• Panel tilt angle matters enormously in winter - I went from 35° to 55° and gained maybe 15-20% on low sun days
• Keeping panels clear of frost/snow first thing (obvious but easy to forget)
• Have you checked for shading? Winter sun tracks so low that things that never caused issues in summer suddenly become problems

What's your battery capacity and charge controller setup? That'll help figure out whether you're generation-limited or if something else is throttling you.

LutonLife | 47 posts

@Mike1986 Those December numbers are pretty realistic unfortunately, even on clear days you're fighting a sun angle of maybe 15–17 degrees above the horizon up in Derbyshire. The peak window is tiny.

One thing that made a noticeable difference for me was tilting my panels steeper in winter — I went from the standard 30° to around 60° and picked up maybe 15–20% extra on sunny days. Doesn't sound massive but every Wh counts in December!

Also worth checking for any partial shading from trees or nearby structures — the low sun path means things that cast no shadow in summer can absolutely hammer your output come winter. A shading analysis tool like PVGIS is free and surprisingly accurate for UK locations.

What's your battery bank size? That's often where the real pain point is this time of year.

Davo51 | 213 posts

Van life here so I'm chasing the sun a bit more than you static folk, but even parked up in Cornwall last December I was barely scraping 300Wh from my 200W roof panel on clear days.

The thing that really opened my eyes was plotting the numbers against the sun's actual arc — in December you've got maybe 7 hours of daylight but the panel's only producing meaningfully for perhaps 2-3 of those. The rest of the time the angle is just brutal.

What's saved me is pairing the solar with a decent Victron MPPT and being ruthless about consumption rather than chasing more panels. The Fogstar 200Ah lithium helps absorb whatever scraps I can gather too.

Have you looked at your consumption side @Mike1986? Sometimes that's the more productive conversation in winter.

KangooDream | 312 posts

@Mike1986 oh mate, I lived this horror story in my Kangoo conversion last January — parked up near Builth Wells, 200W on the roof, and my Victron BMV was basically laughing at me. Two panels doing the work of a particularly unenthusiastic candle.

The thing nobody tells you before you go off-grid in Britain is that winter isn't just about less sun — it's about terrible sun angle. Your panels are essentially getting a glancing blow from a star that can't be bothered to get out of bed properly.

If you haven't already, tilt those panels even slightly southward. I bodged a simple adjustable mount and picked up an extra 20-30% on clear days. Not glamorous, but neither is watching your Fogstar battery slowly weep into the void.