Best way to wire two 200W panels on a shepherd's hut with limited roof space?

Finally getting round to sorting proper solar on my shepherd's hut and I'm a bit stuck on the wiring config. I've got two 200W 24V panels that I picked up cheap, but the roof isn't massive — they'll need to go on slightly different pitches (one each side of the ridge). Not ideal, I know.

My question is whether series or parallel makes more sense here. I'm running a Victron SmartSolar 100/20 MPPT. If I go series I'd get around 48V input which the controller handles fine, but I'm worried that partial shading on one panel (trees nearby in the afternoon) will hammer the output of the whole string. Parallel keeps things safer shade-wise but the lower voltage means more current through the cable run, which is about 6 metres back to the battery box.

Anyone done something similar with mismatched orientations or partial shading issues? I've seen some people suggest fitting individual fuses per panel even in a parallel setup — is that actually necessary at these power levels, or overkill? Using 6mm² cable for the run regardless.

@WattCharlie had almost the exact same dilemma on my motorhome roof last spring — limited real estate, two panels, decisions decisions.

One thing nobody mentions enough: check your MPPT's input voltage range first. Wiring series doubles voltage, which can overshoot cheaper controllers on a cold morning (open-circuit voltage spikes nastily in January). If you're running a Victron SmartSolar, it'll handle the headroom fine, but a budget unit might not.

With 24V panels specifically, series gives you a tidy ~48V Voc which actually plays really nicely with most mid-range MPPTs and reduces cable losses if your run to the controller is longish.

What are you feeding into — 12V or 24V battery bank? That changes the answer considerably. A 24V bank with parallel wiring on 24V panels is a perfectly respectable setup that keeps things simple.

Bit of a different context but on my narrowboat I went through the same headache — roof space is always the limiting factor.

One thing worth considering before you even get to series vs parallel: what MPPT controller are you planning to use? That decision often dictates the wiring for you. If you're going with something like a Victron SmartSolar, check the max input voltage carefully — series wiring on 24V panels can catch people out if you're not watching the Voc figures on a cold morning.

What's your battery bank voltage? That's probably the most important question here. Running a 24V system vs 12V completely changes which config makes sense.

@WattCharlie if they're genuinely 24V panels (Voc around 45V each), wiring them in series gives you ~90V into your MPPT — perfectly fine and actually more efficient over longer cable runs from roof to controller. Thinner cable, less voltage drop. On my static van I did exactly this and it made a real difference.

Main thing to check: make sure your MPPT can handle the combined Voc. A Victron 100/20 or similar will cope no bother, but don't just assume — check the spec sheet before you connect anything.

Only reason to go parallel is if one panel regularly gets shaded while the other doesn't, because shading hits series strings hard. On a shepherd's hut with both panels sitting next to each other, that's unlikely to be an issue.

What MPPT have you got?

Hey @WattCharlie, good shout getting those sorted before the better weather arrives! One thing worth flagging that I don't think others have touched on yet — make sure your MPPT controller's input voltage rating can actually handle whatever config you go with. Some of the budget units have a lower max input than you'd expect, and series wiring especially can catch people out if they're not careful. Also worth checking the Voc at cold temperatures, as it'll spike higher than the dataplate suggests on a frosty morning. Had a mate who fried his controller that way. What MPPT are you running? That'd help narrow down the best wiring choice for your specific setup rather than giving you a one-size-fits-all answer.