Anyone know if a 200W panel will keep a 12V 100Ah battery topped up through winter up north?

Running a small shepherd's hut in the Peak District and trying to work out if my setup is going to cope come November onwards.

Currently got a single 200W panel (Renogy) feeding into a Victron SmartSolar MPPT and a 100Ah AGM battery. Works an absolute treat through summer — battery's usually topped up by mid-morning. But I'm genuinely worried about winter.

From what I've been reading, up north you're looking at maybe 1-2 peak sun hours on a decent winter's day, which means that 200W panel might only be pulling in 200-400Wh on a good day. Less on the grey days that seem to last from October through February.

My loads are fairly modest — LED lighting, phone charging, a small 12V fan heater occasionally (though I know that's a battery killer). Probably drawing 50-80Ah per day on a busy weekend.

So the question is — realistically, is a single 200W panel going to keep a 100Ah battery maintained through proper northern winters, or am I going to be running it flat every other week?

Has anyone in Scotland or the north of England got actual data on this? I know the theory but I'd rather hear from people who've actually watched their Victron app go from 100% to "uh oh" over a cloudy fortnight.

Also wondering whether I'd be better off:

• Adding a second panel
• Upgrading to a larger battery bank (lithium, maybe Fogstar)
• Getting a small wind turbine as a supplement

Or some combination. Budget isn't unlimited so trying to prioritise the right upgrade first.

MidlandsBoater | ⭐ Regular

@SaltyHiker Short answer: it'll struggle. Up in the Peaks you're looking at maybe 1-2 peak sun hours on a grim November day, so realistically you might only squeeze 200-400Wh on a decent day, far less when it's overcast or the panel's got any shade or frost on it.

The Victron SmartSolar is a solid choice mind you, so at least you're not losing efficiency through a cheap controller.

Worth downloading PVWatts or using the Victron MPPT calculator to plug in your location - it'll give you a rough monthly generation estimate.

Honestly for a shepherd's hut through a northern winter I'd seriously consider either a second panel or a small wind turbine as a complement. What's your actual daily consumption looking like? That's really the key question before anyone can give you a proper answer.

NickHughes | ⭐ Regular

@MidlandsBoater is right about the peak sun hours, and there's another factor worth flagging — panel angle matters massively in winter. A flat or low-angle mount can lose you 30-40% of whatever weak sun you do get. If you can tilt that Renogy to around 60-65° for the winter months you'll squeeze noticeably more out of it.

Also worth checking what your actual daily consumption is before panicking. A 100Ah (usable ~50Ah on lead-acid, or more if it's lithium) might be fine if you're only running LED lighting and a small 12V load. It's when people add kettles and heaters that it all falls apart.

What's your load actually looking like? That's the real question before deciding whether one 200W panel is enough or whether you need to add another.

SolarJunkie | ⭐⭐ Veteran

@SaltyHiker The maths here is fairly brutal. At 52°N+ in December you're realistically harvesting maybe 150-200Wh on a good day from that panel — and that's assuming it's clean, correctly angled (aim for 60° tilt in winter), and not shaded by that low winter sun catching nearby trees or the hut roof edge.

100Ah at 12V is 1.2kWh nominal. You shouldn't be cycling below 50% on lead-acid (20% on LiFePO4), so your usable capacity determines everything.

What battery chemistry are you running? If it's a bog-standard AGM you're already behind. My hut setup runs a Fogstar 100Ah lithium — completely different ballgame.

One 200W panel through a Yorkshire winter is borderline even for minimal loads. What's your actual daily consumption figure? Without knowing that, this conversation is just guesswork dressed up as advice.

AlanPalmer57 | ⭐ Regular

@SaltyHiker One thing nobody's mentioned yet — what angle is your panel mounted at? I had a similar setup and tilting my Renogy panel steeper in winter (closer to 60°) made a noticeable difference to what I was actually harvesting on those low-sun days. The sun sits so low in the sky up north that a flat or shallow mount is basically throwing away whatever little light you've got.

Also worth checking what your actual consumption looks like hour by hour. Are you using the Victron app to monitor draw? Sometimes people are surprised where the power's actually going — a small fridge or inverter on standby can quietly murder a 100Ah bank overnight.

What are you actually running in the hut? That'd help work out whether one 200W panel is ever going to be realistic for winter, or whether you need a second panel regardless.