Anyone else struggled to keep a 100Ah lithium topped up on cloudy days with just roof panels?

Spent three winters up in the Dales learning this lesson the hard way, so yes — absolutely.

My motorhome runs a 100Ah Fogstar Drift and I've got 200W of Renogy panels bolted to the roof. On a proper grey Yorkshire day you're sometimes pulling maybe 15-20W if you're lucky. That's barely enough to offset the fridge, never mind charge anything or run the heating controller.

What actually saved me was adding a B2B charger so I top up properly whenever I'm driving — even a short 40-minute run to the village shop makes a real difference. I use a Victron Orion-Tr Smart and it's transformed winter living honestly.

A few things I've found help on dismal days:

• Shade your loads, not just your generation — I got obsessive about auditing what's actually drawing power
• Tilt your panels if you can, even a small angle change on low winter sun makes a noticeable difference
• Accept that November to February up north, shore power or a run-and-charge strategy isn't cheating, it's just realistic

The honest truth is 100Ah lithium + 200W solar is genuinely a summer setup in the UK unless you're very disciplined or very far south. I see a lot of folk on here surprised by this and I get it — the marketing always shows panels in blazing sunshine, not Harrogate in January.

Anyone running split-charge setups alongside their roof panels? Curious whether others have settled on B2B or just gone down the alternator-direct route. And has anyone tried adding a small folding panel for those really desperate cloudy days?

@PennineCamper 200W on a UK winter roof is basically a decorative feature.

@RetiredEngineer harsh but honestly fair — I've got 400W on my shepherd's hut roof and still watched my Victron BMV-712 weep quietly through November like it owed me money.

The real fix that saved my sanity: a DC-DC charger wired to the van/tow vehicle alternator for those grim grey days — Sterling or Victron Orion-Tr Smart both do the job. Panels for sunny days, alternator for when the Dales are doing their best impression of a wet flannel. Belts and braces, as they say.

@PennineCamper had exact same issue with my static van last winter — 200W just doesn't cut it when you're getting 3-4 hours of proper sun on a good day.

Ended up adding a portable 100W panel I can angle toward the sun rather than just lying flat on the roof. Makes a genuine difference on those low-angle winter days.

Also worth looking at a small leisure battery charger running off hook-up when you're on a site — even a basic Victron Blue Smart IP65 keeps things topped without relying on the panels at all.

The roof panels are great April–September but I'd not count on them as primary charging Nov–Feb in the Dales specifically. That latitude is brutal.

@PennineCamper one thing worth considering alongside more panels is a DC-DC charger if you're driving at all between spots. Even a 30A unit will put serious amps into your Fogstar Drift during a two-hour run between Dales villages — often more than your roof panels manage all day in December.

Also worth checking your panel angle. Flat roof mounts lose a massive amount in winter because the sun sits so low in the sky up north. Even propping the front edge up 20-30° with a tilt kit when you're parked can make a noticeable difference to what your MPPT is actually seeing.

None of this replaces getting more wattage on the roof long-term, but it keeps you topped up while you're planning the upgrade. What MPPT controller are you running currently?