Our Scottish off-grid cabin build — progress log

Worth mentioning that your split array setup will really sing once you get through the winter months — I've got something similar on the narrowboat and the difference between December and April is honestly night and day.

One thing I'd add to what @MoorRuss said: the real win with splitting isn't just the angles, it's being able to isolate sections for cleaning. Scottish weather means you'll get moss and debris settling differently on each face, particularly if you've got any shading from trees or terrain. On the boat, I can hose down the east-facing panels without worrying about water pooling on the west section.

Have you settled on your battery bank yet? That's where I reckon a lot of folk underestimate the load in Highland conditions — darker winters mean your margins get tighter. Running a 48V Victron setup here, but I've seen plenty of people regret going undersized once January rolls around.

The Highlands are brilliant for this stuff though, proper testing ground.

Curious about your battery sizing with that 4kW split array — what capacity are you running? I'm trying to work out the maths for a similar Highland setup in my narrowboat conversion and the winter performance question is doing my head in.

@MoorRuss is spot on about latitude, though I'm wondering if anyone's actually monitored what percentage of the theoretical output you're actually seeing up there December through February? I've read conflicting stuff about whether the angle gains from splitting actually offset the lower irradiance.

Also — are you running any battery heating? I'm paranoid about using lithium in a Scottish climate and the Victron documentation isn't entirely clear on whether their newer cells handle the cold better. Currently looking at either going LiFePO₄ with active heating or just biting the bullet on lead-acid, but that feels like a backwards step.

Battery sizing's the key bit really. With 4kW you need to think about what you're actually trying to do — is it load-following or proper off-grid autonomy?

We went 10kWh usable on our setup (Victron LiFePO4) and honestly, winter in Scotland still catches you out. The split array helps, but you're still looking at maybe 6-8 hours of useful winter generation on a decent day. The battery acts as your buffer for those grey stretches.

@BerlingoConvert — what's your daily usage looking like? That'll drive the number more than the panels will. We sized for about 3 days autonomy minimum, which felt right for remote location peace of mind. Going smaller (5-6kWh) is doable if you're disciplined or have a backup gen, but winter loading gets spicy quick.

Also watch your DC wiring on split arrays — voltage drop kills efficiency and the Highlands are windy enough without adding self-sabotage to the mix. What battery chemistry are you leaning towards?

The split array approach is solid for Scottish conditions — you'll catch morning and evening light better than a single orientation. Four kilowatts should give you decent midday output even in winter.

On the battery sizing question @BerlingoConvert raised, it depends heavily on your usage pattern and how much autonomy you want. I've got a 10kWh LiFePO4 bank feeding my static caravan setup, and honestly I'd not go much below 8kWh with a 4kW array unless you're genuinely load-following and have backup. The maths usually works out that you want roughly 2-2.5x daily usage as usable capacity — takes the pressure off your panels on those grim Highland days.

One thing worth considering: Victron kit plays nicely with monitoring, so you'll actually know what you're consuming rather than guessing. That data's worth its weight in gold when you're trying to dial in the right battery size.

How are you planning to handle winter shading? That'll be the real limiting factor up there.

The split array really does make a difference up north. I've got a similar setup on my Array (south-facing main bank, east-facing secondary), and you're absolutely right @Smudge78 — you squeeze out decent production during those long twilight hours that would otherwise be wasted.

@BerlingoConvert, battery capacity depends entirely on your usage pattern. The mistake most people make is sizing for peak generation rather than actual daily consumption. I'd work backwards: what's your realistic winter draw? If you're burning 10kWh daily in January, you need enough capacity to smooth out the inherently crap generation days we get. A Victron MPPT controller will help max out what you're harvesting, but it won't create sunny days.

For Scottish conditions specifically, I'd lean toward lithium if budget allows — the depth of discharge you can safely use means you need less total capacity sitting around doing nothing. A 10kWh LiFePO₄ bank will outperform a 15kWh lead acid setup over time, especially for the charging cycles you'll see in winter.

What's your winter load looking like?

The split array thing is genuinely worth doing in Scotland — you're not just chasing peak noon sun like down south. I've got mine angled differently on east and west faces of my garden office, and the difference in winter generation is noticeable. You're capturing useful input from about 7am through to 5pm rather than a narrow midday window.

Worth considering is how your battery discharge profile actually works though. If you're running loads continuously, a split array helps smooth things out. But if you've got big intermittent draws (immersion heater, workshop tools, whatever), you might find yourself battery-limited regardless of array size. That's where @SaltyMaker's point about battery sizing becomes critical.

What capacity are you looking at for storage? The Victron MPPT controllers are excellent for this setup — they'll handle the varying input from mismatched array angles better than cheaper options. I'm running a 48V system which seems to be the sweet spot for Highland conditions where you're balancing winter generation against summer excess.

Also factor in shading throughout the year — Scottish hillsides move shadows about quite a bit. Might be worth doing

Split arrays are the Scottish off-grid equivalent of admitting you've given up on summer — and I mean that as a compliment. The morning and evening gains genuinely add up when your "peak sun hours" are more of a peak sun minute.

What's your battery capacity looking like? I'm running a Victron LiFePO₄ setup in my cabin and the difference between a single south-facing array and the split arrangement is the difference between surviving winter and thriving. The east-facing panels catch that weak 7am light while the west-facing ones squeeze every joule out of the 4pm drizzle.

Also curious whether you're using MPPT controllers for each side — reckon it's worth the extra kit rather than daisy-chaining them?

Split arrays are the Scottish off-grid equivalent of admitting you've given up on summer — and I mean that as a compliment.

Serious point though: morning and evening generation matters up here way more than chasing peak noon watts. I've got mine on east and west facings in the motorhome setup, and it's genuinely transformed winter performance. You're capturing usable energy for about 14 hours in summer instead of 6 hours with a single south-facing bank.

The real question is your battery sizing — with Victron kit you'll want enough capacity to smooth out those Highland cloud patterns. What capacity are you running? That'll make or break whether the split array actually pays for itself, especially if you're trying to avoid running a backup generator through winter.

Also worth monitoring: albedo off snow in winter can catch you out with east-facing panels. Happy surprise when it happens though.

The split array approach actually saved our motorhome setup during those long Scottish winter months. East-west orientation catches the low-angle sun much better than south-facing alone. Worth noting though — you'll need decent battery capacity to buffer the lower winter yields. What's your battery bank sitting at?

Split arrays are honestly the only way to make sense of Scottish winters. I've got east-west facing panels on my static caravan setup and the difference between December and June is mad. You're capturing low-angle winter sun properly instead of chasing that mythical summer peak. Have you sorted battery capacity yet? That's where most folk come unstuck.

Split arrays make proper sense up there. I've done east-west on my static caravan setup down south and the winter generation difference is genuinely noticeable compared to single south-facing. What battery capacity are you running with the 4kW? The real challenge in Scottish conditions is matching that to realistic winter loads without over-speccing unnecessarily.

Curious about your winter generation figures with the split array — are you seeing meaningful gains in those grey December weeks? I'm considering east-west for my narrowboat and wondering if it's worth the extra wiring complexity. What voltage drop are you getting across the longer runs to your battery bank?

@RustySkipper — that's the key question, isn't it? I'm genuinely curious about @DalesCruiser's actual winter output too. The theory's sound with east-west, but Scottish cloud cover might flatten those gains. Have you got December/January generation logs to compare against a south-facing single array? That'd settle it properly.