43' toy hauler, solar/storage/generator refactor. Looking for input.

[Blistovmhz]

So I've got a 43' toy hauler. Currently have the original 6500w onan generator, around 1500w solar (rigid) split into 2 120v arrays into 2x mppt controllers, charging 2x 48v@100ah packs (and a few other incidentals).
I'm going to be redoing my roof and wanted to do a full roof basket/patio anyway, so I'll need hand-rails, and figure those hand rails fold down to the center, so call them about 40' x 4' each. Rigid flat mounted panels suck in >35* heat as they trap heat under, radiate heat to the roof which radiates right back, resulting in dramatic decrease in pv efficiency. That said, with my fridge and all my incidentals running in 40* heat, I'm still only drawing a max of around 500w before the AC. The AC of course can't keep up in 40* anyway and I'm going to be switching it out to 2x 12k or 18k mini-splits, which combined will draw less than the 2kw of the current forced air unit. Even at 40*, I can ALMOST run everything, including the AC entirely on solar, but I do sorta wanna be FULLY self-contained.

So the thought is to build the fold down hand-rails and use them to mount flexible panels. That gives me a rough surface area of about 320sq-ft, or around 3200w peak PV generation. My thinking is that this not only more than covers all of my power needs forever, in pretty near all conditions, but the PV efficiency should actually be higher than the rigid flat mounted, as they'll be bifacial, vertically mounted, and thus not trapping heat on the roof and better able to radiate heat and make better use of convection. Overall, I think the PV temps will stay down subtantially lower and I'd be willing to bet I come close to that 3kw mark even at 40*C. Thats MORE than enough to run the fridge, starlink, couple laptop, my instrumentation, and 2x mini splits, and still have enough left over to probably end the day with a full charge (10kwh).

Also, with the roof setup this way, cell occlusion becomes much less of an issue as there's nothing else on the roof. No vents, no AC, nadda.

The big question though, is how much dick waving is this, vs just getting a smaller, more efficient generator, that I need to run a few times a year? In the year I've been off-grid, I've run the generator only in 40+* weather in the Mojave, or in the PNW where we dont' see sun for a few weeks at a time. I don't WANT to spend a ton of time in either during the bad season, but I'm sure it'll happen.

Also, who's got recommendations on either very light flexible bifacials, or flexibles? I've seen a few flexibles pop up in the $1/w range recently, though I"m not sure I trust it.

 

[sunshine_eggo]

Some thoughts...

They will still get plenty hot, but they should be cooler than near flush mounted on the roof.

Bifacial panels don't get you much unless they're about 1m off their mounting surface to provide enough backside exposure, and surfaces need to be reflective.

Betting on getting rated power at 40°C is a losing bet. If you look up the NOCT ratings, that factors in elevated cell temps in the 40-50°C range at 25°C ambient. When it's 40°C ambient, they're going to be even hotter.

Shading should be eliminated as you indicate.

Pure vertical is often no better than pure horizontal. Great in winter. Meh in summer.

Flexible panels are notoriously short lived. Supposedly ETFE coated panels are supposed to last notably longer. Be prepared to replace them every 1-3 years.

When you look at the pure acquisition costs of a generator, it's hard to go solar unless you factor in fuel costs. Then it becomes a matter of time to break even.