Shepherd's hut solar in a shaded Welsh field — worth the hassle?

Finally got the shepherd's hut sitting on a sloped bit of land in Powys, which is wonderful except the nearest decent sun exposure means running cables about 12 metres to a ground-mounted array rather than just slapping panels on the roof. The roof option gets maybe 3–4 hours of usable light in winter because of a tree line to the south-west. Ground mount in the adjacent clearing would get closer to 6–7 hours on a decent day.

Currently running a modest 200W setup — two 100W Renogy mono panels, a Victron SmartSolar 75/15, and a 100Ah Fogstar Drift LiFePO4. Powers lighting, a 12V compressor fridge, phone charging, and occasionally a small inverter for a laptop. Works fine in summer but last January it was genuinely grim — two or three days of near-zero charge whilst working remotely.

The 12m cable run to a ground mount doesn't scare me, but I'm wondering whether it's worth bumping up to 400W at the same time, given I'm digging a trench anyway. Probably 6mm² cable to keep voltage drop manageable over that distance. Has anyone done a similar relocation on a site like this — did the extra hours of winter sun actually transform day-to-day usability, or does Welsh winter diffuse light make it all a bit academic regardless of panel position?

Jess1972 | 847 posts

@CliveKnight 12 metres is absolutely nothing to worry about — I'd go with 6mm² cable for that run to keep voltage drop negligible, especially if you're planning anything over 200W. Ground mounts in Welsh fields are genuinely brilliant once you've got them in; you can angle them properly rather than being stuck with whatever pitch your roof gives you, and tweaking the tilt seasonally takes two minutes.

The bigger headache in Powys honestly isn't the cable run, it's the horizontal rain getting into any outdoor junction boxes. Get proper IP67-rated connectors and don't cut corners on weatherproofing — learnt that the soggy way myself in Ceredigion!

What's your intended usage? Weekends only changes the battery sizing conversation quite significantly compared to extended stays.

Callum1982 | 312 posts

@CliveKnight Powys is gorgeous but yes, the shade can be brutal in those valley spots! @Jess1972 is right about the cable run being manageable. One thing worth thinking about with ground-mounts on sloped Welsh land — make sure your frame is properly ballasted or concreted, because the wind funnelling through those hills can be vicious even when it looks sheltered. Also consider whether the slope faces roughly south-southwest, as that's often your best compromise in mid-Wales for catching the lower winter sun. What's your expected load? If it's just lighting and a bit of USB charging for weekend use, even a modest 400W array should serve you well despite the less-than-perfect conditions.

PanelMatt | 312 posts

@CliveKnight Welsh weather is brutal on panels but honestly ground mounts are better for maintenance anyway — you can actually reach them to clean off the inevitable sheep muck and lichen.

@Jess1972 has the cable sorted. Just make sure you're using proper DC-rated armoured cable for that ground run, not just chucking twin-and-earth in a conduit. If it's crossing any ground that gets walked or driven on, bury it properly.

For a shepherd's hut in Powys I'd also oversize the array more than you think necessary — shade losses plus the grey drizzle months mean you want headroom. Bifacial panels on a ground mount actually help a bit with diffuse light reflection off wet grass too.

TonyRoss | 1,203 posts

@CliveKnight Powys is gorgeous but yes, those valley sites can be properly shaded — been there myself! One thing worth thinking about beyond the cable run is the panel orientation on a ground mount. You've got far more flexibility than a roof install, so you can tilt and face them optimally rather than being stuck with whatever angle the hut roof gives you. In shaded Welsh conditions that extra few degrees of optimisation genuinely matters. Also worth considering a ground mount with adjustable tilt brackets so you can tweak seasonally — winter sun sits so low up there that what works in July is fairly useless come November. @Jess1972 is right about the cable sizing being straightforward. What panels are you looking at and what's your actual load requirement? That'll determine whether a small MPPT setup covers you or whether you need something beefier.