Transferring static caravan solar knowledge to a motorhome — what actually changes?

I've spent the last three years dialling in a 800W solar array on my static caravan in Wales — four 200W Renogy panels, a Victron SmartSolar MPPT 100/30, and a 200Ah Fogstar Drift LiFePO4 bank. I know that setup inside out. Now I'm seriously looking at a second-hand Bessacarr motorhome and want to bolt a decent solar setup onto it, but I'm realising the assumptions I've built up might not all transfer cleanly.

The obvious differences I can see: roof space is dramatically more constrained, you're dealing with moving shadows and panel orientation that changes constantly as you move/park, and you presumably can't just wire up the same static runs because the environment vibrates and flexes. I'm also wondering whether a motorhome alternator complicates or simplifies the charging picture — my static caravan doesn't have that variable at all.

Is the Victron ecosystem still the go-to at this scale for a motorhome? I'd probably be looking at 300–400W realistically on the roof given the space, and a single 100Ah LiFePO4 to start with. Does a smaller MPPT like the 75/15 make more sense at that scale, or do people typically overspec the controller to leave headroom for expansion?

Anyone who's gone from a static/cabin setup to a mobile one — what genuinely surprised you about the differences in how you manage the system day-to-day?

AlisonHughes | 47 posts

@EdHamilton Great foundation to build from! The biggest practical shift you'll notice is shading management — on your static you can optimise panel placement once and forget it, but in a motorhome you're constantly parking in different orientations relative to the sun. Your Victron MPPT will handle partial shading reasonably well, but it's worth thinking about whether you'd wire panels in series or parallel differently given that.

Also, weight and roof curvature genuinely matter — those Renogy panels are decent but fairly heavy for a vehicle roof. And vibration over time is harder on connections than you'd expect.

The good news is your Fogstar Drift and SmartSolar combination translates brilliantly — that's solid kit that plenty of motorhomers run successfully. Your Welsh weather experience with low-light harvesting will also serve you well on the road! What size vehicle are you looking at?

MartinParker64 | 203 posts

@EdHamilton The thing that caught me out moving from a static setup was panel orientation. On your caravan roof in Wales, you've likely got a fixed optimal tilt dialled in. In a motorhome you're parking wherever you can, often facing the wrong direction entirely, so your 800W on paper might realistically deliver half that on a poor pitch.

Worth budgeting for a portable folding panel as a supplement — park the van, deploy it at the best angle separately. Also your Victron MPPT will handle the variable input brilliantly, that's genuinely good kit to be carrying across.

One practical Welsh-specific note: you already know low-light performance matters there, so you're not going to be surprised by overcast harvests like folk coming from sunnier static sites might be!

AshSeeker | 31 posts

@EdHamilton Really interesting question — I'm in a similar position, having spent time optimising solar on a narrowboat before thinking about mobile setups.

One thing I'd flag that nobody's mentioned yet: cable runs. On a static you can afford generous cable lengths without worrying much about voltage drop. In a motorhome the routing gets complicated around the body structure, so it's worth recalculating everything fresh — even if your component ratings stay identical.

Also curious whether you've considered how your Victron SmartSolar handles the vibration environment long-term? I've read mixed things about mounting orientation on moving vehicles. Has anyone had issues with that specifically?

Your Fogstar Drift should transfer well though — LiFePO4 handles the charge/discharge cycling of mobile use better than AGM ever would.

PylontechFan | 312 posts

@EdHamilton One thing nobody's mentioned yet — your Victron SmartSolar will handle the transition brilliantly, but do review your battery temperature compensation settings. In a static caravan your Fogstar sits in a relatively stable environment, but a motorhome boot or underfloor locker can swing dramatically, especially on winter trips up to Scotland or similar. LiFePO4 is less forgiving about charging below 5°C than your typical AGM setup.

Also worth considering: with a static you're essentially always grid-tied for emergencies. On the road you'll want to think seriously about a DC-DC charger to top up from the alternator when solar's struggling. Victron's Orion-Tr Smart integrates nicely with your existing ecosystem. Your 200Ah bank is decent but you'll feel it more acutely when you've had two overcast days and no hookup nearby! 😄

OffGridJack | 847 posts

@EdHamilton One thing that genuinely surprised me going from a fixed cabin install to my narrowboat was cable run management. On a static you probably have generous, direct runs to your MPPT. On a motorhome you're routing around cabinetry, through bulkheads, potentially doubling your run lengths — and suddenly your volt drop calculations need revisiting.

Worth resizing conductor cross-section before you commit to anything permanent. I went up to 10mm² on my boat runs where I'd have used 6mm² on land.

Also, vibration. Every connection point needs checking after the first few hundred miles — things loosen that you'd never think about in a static setup. Nylock terminals or threadlock on mounting hardware became standard practice for me pretty quickly.

The core system logic you've already learned transfers fine — it's the physical installation discipline that changes.

DodgyHermit | 203 posts

The biggest thing I'd add from running solar on my shepherd's hut (also fixed, tilted optimally) — you'll genuinely miss being able to angle your panels. On a motorhome roof they're flat and fixed, so your winter harvest drops off a cliff compared to what you're used to. Your 800W static setup probably performs like 500W equivalent in a van through December/January.

Also worth knowing: vibration from driving will gradually work loose any connections you thought were solid. I re-torqued everything on a mate's camper after six months and found three terminals had backed off noticeably. Doesn't happen on a static install obviously.

@PylontechFan makes a fair point about the MPPT — that bit of your knowledge transfers cleanly at least. Your Fogstar LiFePO4 experience will also serve you well; the chemistry behaves identically regardless of whether it's moving.