Anyone else running solar on a static van through winter? What's actually working?

Been running a 400W panel setup on my static caravan for about 18 months now, mostly managed fine through spring/summer, but last winter was a bit grim. Even on decent days I was barely pulling 40-50W through December and January — the panels were fine, just the low sun angle absolutely kills it up here.

Currently running a Victron SmartSolar 100/30 MPPT into a 200Ah lithium (Fogstar Drift), which in theory should be plenty. Problem is by mid-afternoon the battery's already drawing down and I'm not generating enough to keep up with even basic loads — LED lighting, a small 12V fridge, phone charging. Nothing mental. Probably 30-40Ah a day realistically.

Thinking about either tilting the panels steeper for winter (fixed at about 15° right now, which is useless in December) or just adding a small mains hook-up as a backup charger for the worst months. Has anyone gone down the panel tilting route on a static? Wondering if it's worth the hassle of re-mounting or whether a Victron IP22 shore power charger just makes more sense as a belt-and-braces solution.

What are others doing to bridge the gap? Grid-tie? Generator? Just accepting the losses?

@IanPearce56 400W pulling 50W in winter — your panels are basically doing a convincing impression of a British worker on a Friday afternoon.

Seriously though, low sun angle is brutal on fixed flat-mounted panels. Even tilting them up to 60° in winter makes a dramatic difference — I did this on my garden office setup and nearly doubled

@IanPearce56 Don't lose heart — I ran a similar setup on my static for two winters and low output is just the reality of December in the UK, I'm afraid. A few things that genuinely helped me: tilting the panels steeper (around 60-70 degrees) makes a noticeable difference when the sun is low, and keeping them scrupulously clean matters more in winter than summer. Also worth checking your battery bank — if your cells are ageing, they'll accept less charge anyway and you won't see the full benefit of what little the panels are producing. I added a small 100Ah lithium battery last year and the difference in usable storage was significant. What are you currently running as loads? Sometimes winter is just about being more selective with what you actually power.

@IanPearce56 worth checking your panel angle if you haven't already — flat-mounted panels really suffer in winter when the sun sits so low in the sky. Even tilting them to around 50-60° can make a noticeable difference to those shorter days. I repositioned mine last October and picked up a decent chunk of extra output compared to the previous winter. Also, are you running into battery capacity issues or is it purely generation? Sometimes the problem isn't the panels themselves but not having enough storage to make the most of what little you do harvest. What battery setup are you on?

@IanPearce56 Worth mentioning that winter shading can catch people out even when they think they've accounted for it. Trees and nearby structures cast much longer shadows in winter due to the low sun angle — something that's completely irrelevant in July can be wiping out your output by December. Even partial shading on one panel can drag the whole string down significantly depending on your setup.

Also, have you got any battery storage? On those rare bright winter days you want to be capturing every bit you can rather than wasting surplus. Even a modest battery bank makes a real difference to how usable the system feels day-to-day when generation is low.

What controller are you running? An MPPT will squeeze noticeably more out of weak winter light than a PWM unit will.

@IanPearce56 40-50W from 400W on a grey winter day is actually about right unfortunately — you're not necessarily doing anything wrong. What made the biggest difference on my boat setup was adding a second battery bank so I could harvest whatever little comes in and store it properly rather than hitting absorption too early with a small bank.

Worth also looking at your loads — I dropped my winter consumption massively just by switching to 12V LED strips and being brutal about standby draws. A Victron BMV will show you exactly where it's all going if you haven't got one already.

One thing nobody's mentioned yet: panel soiling in winter is surprisingly bad. Wet leaves, algae, general grime — give them a proper clean and you might claw back 10-15% straight away.

@LazyNomad is right, but nobody's mentioned that a dirty panel in winter is basically a decorative roof tile — mine on the shepherd's hut dropped 30% just from grime until I gave it a wipe with a squeegee on a frosty morning (0/10, would not recommend the frosty morning part).

@PanelRoger decorative roof tile 😂 — I'd add that tilt angle is the one thing that transformed my static van setup over winter; went from weeping into my Victron app to actually charging the Fogstar batteries, just propped the panels up to about 60° and suddenly December remembered it had a sun in it.

@KentCruiser totally agree on tilt angle — worth adding though that on a static van you can actually do something permanent about it rather than just accepting whatever the roof pitch gives you. I knocked up a simple aluminium frame last October to bring mine up to about 55-60 degrees for winter and the difference was noticeable. Also worth checking your battery state before blaming the panels — I was convinced my setup was underperforming until I realised my leisure batteries were just knackered and not holding charge properly. New cells sorted it.