Anyone know if a 200W panel will keep a 100Ah leisure battery topped up over winter?

Running a small off-grid setup at my static caravan in the Peak District and trying to work out whether a single 200W panel is going to be sufficient to maintain a 100Ah leisure battery through December and January without it dropping into a damaging state of charge.

Current draw is fairly modest — just a 12V LED lighting circuit, a small water pump, and occasionally charging phones/laptops. Rough estimate puts me at maybe 20-30Ah per day consumption.

My concern is the actual usable solar irradiance in a UK winter. I know we're looking at perhaps 1-2 peak sun hours on a good day in the north of England, which would theoretically give me 200-400Wh — enough on paper, but:

• How often are those "good days" actually occurring in December?
• Panels accumulate significant efficiency losses in low-angle winter sun
• Shading from nearby trees becomes far worse once leaves drop (though that does help somewhat)
• My panel is fixed at around 30° tilt, not optimal for winter

I'm running a Victron SmartSolar MPPT 75/15 controller which at least gives me decent monitoring through the app, so I can track what's actually going in vs. coming out.

Has anyone with a comparable setup — particularly in northern England or Scotland — got real-world data from winter months? I'm wondering whether I should be looking at:

1. Adding a second panel in series/parallel
2. Bumping up to a 150Ah battery to give more buffer
3. Simply accepting I'll need occasional top-ups via a mains charger when visiting

The battery itself is a Fogstar 100Ah lithium, so at least depth of discharge isn't as critical as it would be with AGM

@BarryWood short answer: probably not reliably, no.

Peak District in December you're looking at maybe 1-1.5 peak sun hours on a good day, and you'll have plenty of days with near-zero generation. A 200W panel theoretically gives you 200-300Wh daily — but real-world with cloud, low sun angle, and panel orientation you might see 100Wh if you're lucky.

A 100Ah battery at 12V is 1200Wh usable (assuming 50% DoD on a standard wet leisure battery). One decent sunny day won't make a dent in a week's deficit.

What's your actual consumption though? If the caravan is genuinely just on trickle/maintenance over winter with nobody staying, the panel might manage maintenance charging fine. Big difference between keeping a battery healthy versus actually powering loads.

Worth grabbing a Victron SmartSolar MPPT if you haven't — the Bluetooth monitoring will show you exactly what you're generating daily.

@ExSquaddie49 is right, and the Peak District makes it worse — you're not just fighting short days, you're fighting cloud cover and low sun angles that kill panel output even midday.

Worth actually doing the maths: 200W × 1.5hrs = 300Wh on a good day. Your 100Ah battery (assuming 12V, so 1200Wh) will barely see meaningful charge if you're drawing anything at all.

Had similar issues on my boat one winter. Even with decent Victron kit managing the charging properly, a single panel that size genuinely struggles.

Realistic options:

• Add a second panel if you have roof space
• Stick a small mains trickle charger on when you're there
• Accept you'll need to manually top up periodically

What's your actual consumption like? If it's genuinely minimal — just a few LEDs and a controller — you might scrape by.

@ExSquaddie49 and @ExBrickie have covered the solar side well. Worth adding — if your caravan is static and has mains access even occasionally, a decent smart charger (Victron Blue Smart is what I use) set to a storage/maintenance mode will do more reliable work through December than the panel will.

Also depends heavily on what you're actually running. If it's just keeping the battery healthy with minimal draw, a 200W might scrape by on a clear December day. If you've got a fridge, lighting, water pump etc running regularly, you're going to be pulling more than you're putting in most weeks.

A second panel would transform the situation — two 200W panels in parallel made a noticeable difference to my winter figures compared to running a single panel.

@BarryWood lived through almost exactly this situation with my shepherd's hut first winter. Even with panels pointing south at the optimal tilt, December felt brutal — not just the short days but the angle the sun sits so low that panels spend half the morning in their own shadow if there's any obstruction.

One thing nobody's mentioned yet: the battery itself. If that 100Ah leisure battery is an older lead-acid unit, you're really only working with about 50Ah usable before you start damaging it. That effectively halves your storage before the solar question even matters.

Swapped mine for a Fogstar Drift 100Ah LiFePO4 last year — not cheap, but suddenly the same panels felt dramatically more capable because I could actually use the full capacity. Might be worth considering before adding panels.

@MuddyNomad that shepherd's hut experience is really useful context — I'm in a similar situation with mine. One thing nobody's mentioned yet: what's the battery's actual state of health? A 100Ah leisure battery that's seen a few winters might only be holding 60-70Ah in practice, which completely changes the maths.

Also worth checking your panel's voltage at the controller during a dull December day rather than just going off the rated wattage. I was surprised how far mine dropped on overcast days up in Northumberland.

@BarryWood what controller are you running? If it's a basic PWM unit rather than MPPT, you're losing a meaningful chunk of what little generation you do get. Swapping to even a budget MPPT made a noticeable difference to my winter figures.