Anyone else struggled to fit a 200W panel on a Transit roof with the solar vents in the way?

Not a Transit but had similar headaches on my narrowboat cabin roof — vents, handrails and a mushroom vent all conspiring against me when I tried to fit a pair of 100W Renogy panels.

Ended up going portrait orientation instead of landscape and it made all the difference. Sounds obvious but I'd been fixating on landscape for no real reason.

Few things worth considering:

• Tilt mounts can help you squeeze panels into awkward gaps and get better winter angles at the same time
• Two 100W panels instead of one 200W gives you way more flexibility for routing around obstacles — same output, easier to position
• Check the actual usable roof space with a tape measure before you order anything, not just the total roof dimensions

The other thing I'd say is don't underestimate how much a vent in the wrong spot kills your shade tolerance. Even a small shadow from a vent cowl can hammer your output if your panels are wired in series. Parallel wiring or a decent MPPT like the Victron 75/15 handles partial shading a lot better.

Anyone managed to get a full 200W single panel on a standard Transit wheelbase without going on the very front of the roof? Curious whether the front mounting position causes any motorway wind noise issues at speed.

@BazBurns oh this took me right back to my narrowboat days — the cabin roof is an absolute jigsaw puzzle isn't it.

What eventually saved my sanity was sketching the entire roof to scale on graph paper first, including every vent mushroom and handrail bracket, before anything was ordered. Sounds old-fashioned but it meant I could physically move paper cut-out panels around until something clicked.

I ended up ditching the idea of two identical panels altogether and went with one 100W and one 80W — slightly different dimensions that just slipped around the obstacles where a matched pair never would have.

Worth checking if Renogy or Victron SmartSolar controllers will handle mismatched panels in parallel too, because that was my next rabbit hole once the physical fitting was sorted.

@BazBurns the mushroom vent placement is the killer — mine was bang in the centre of the roof which ruled out any standard portrait-orientation 100W panel without overhang.

What sorted it for me was switching to two smaller flexible panels (went with a pair of 80W units) and routing them either side of the vent, wiring in series to keep cable runs tidy. Lost about 40W theoretical peak but gained a clean, unobstructed installation with no shading hotspots from the vent stack — which matter more than raw wattage in practice.

Worth measuring your actual usable rectangles before ordering anything. Tape out the dimensions on the roof and photograph it — you'll quickly see whether portrait or landscape orientation wins, and whether a single 200W or split configuration makes more sense for your specific obstacle layout.

@BazBurns narrowboat roofs are genuinely a special kind of spatial nightmare — at least on a van you're working with a flat rectangle. I ended up doing a proper paper template of my garden office roof before committing to any drilling, measuring every obstruction twice (and still got one hole slightly off, naturally).

One thing worth considering: have you looked at flexible panels? They're not ideal for long-term heat dissipation but they'll wrap around awkward profiles and dodge obstructions that would otherwise rule out rigid panels entirely. Renogy do a 100W flexible that's surprisingly decent for the money.

Alternatively, @TransitAdventure is right about mushroom vents being killers — I'd actually relocate the vent before compromising panel placement if possible. A repositioned vent costs pennies compared to the output you lose from a badly-oriented or partially-shaded panel.

@BazBurns know this pain all too well! Did mine on a 57-plate Transit a couple of years back and the roof vents nearly had me beaten before I'd even started. What eventually saved my sanity was doing a proper cardboard template of the entire roof first — sounds daft but half an hour with some old cereal boxes showed me exactly what I had to work with before I'd spent a penny on brackets.

On the narrowboat front, have you looked at flexible panels at all? A mate of mine runs a pair of 100W semi-flexibles on his cruiser stern boat and the ability to curve them slightly around obstacles made a big difference to his usable surface area. Not ideal for heat dissipation mind, but for a secondary system it might be worth considering depending how much shade you're dealing with.

@BazBurns mate, a static caravan roof is basically just one big unobstructed solar farm and I still managed to place my first Renogy panel directly over the one rivet that needed access — some of us are just gifted.