A mix of my experience and info gleaned from Boots and Mike. I ripped the single factory 150w panel off and fitted 3 x 200w fixed panels. The panels cost me $345 total delivered, and perform very well. I swapped out the Jayco factory pwm controller for an Epever 75/40, connected in turn to 2 x 120ahr agms. I ran the 3 x panels in series and each panel has 2 bypass diodes so partial shading which would otherwise kill me, has little effect. Connected in series translates into a better harvest over a longer period, in fact before 7am and after 7pm I still get amps into the batteries, and we're over 30amp in the sweet spot. Series also requires a controller able to take the combined voltage in from the panels, and the increased amps out to the batteries. Series was a bonus for me because I didnt have to upgrade any cabling. I used the panels MC4 connectors with joining cables I knocked up, and the existing factory roof entry GP terminal box Jayco put on the roof. My terminal box is unfortunately under the original panel, and now under one of the new panels. Not ideal, but better than tempting fate with a new roof penetration. I ran all my panel cabling via suspended uv conduit bored through the side of the panel frames. Nothing sits on the roof so I didn't affect the roof water run off in any way. I have 3 x blanket panels 100w, 150, 200w. I carry them all in the van but for all but one they are just a set of redundant upgrades purely for the Engel in the car. I have a Anderson input/ouput on the bullbar to plug in the blanket. I also have a Anderson input/output direct to the vans batteries on the vans chassis around midway along the van on the road side. I use that van plug for tyre pump, water pump, lights for the camp shower etc and I can also connect the blanket solar panel if required. I use a Victron SmartSolar 75/15 for the blanket panels. From everything I could find to read, solar controllers can be happily connected to the same batteries without any significant adverse impact, types seemed irrelevant. We all seem happy enough that 100% charge isn't the aim of the smart alternator when it comes to the car, so I cant see why sub 100% would be so non negotiable with other batteries anyways.
For our infield use we always camp with the van in full sun where possible, purely for the solar. We have significant experience ie we camp a lot, and a lot of it up north and that works fine for us. There are exceptions of course but most of the time with the van angled appropriately we keep the midday to arvo sun behind the van and the shade on the awning side. We've not felt the need to seek out shade, and forsake solar harvest, we gain little from the shade but loose out big time with solar so for us thats a obvious choice. Im a big fan of not having a 2 hour camp setup with $hit everywhere, I prefer to stop, stay connected and deploy minimal hardware and ordinance, light the fire and get naked .... only joking, or am I. Every though I have the input on the van, panels have never been plugged in other than the initial buggering about to see if it works. We have always managed to avoid the shade, never suffered as a result and for an overnighter or a couple of days its doesn't matter anyway. I now have a long Anderson lead that I run from the vans Anderson to the cars Anderson to top up the car from the vans batteries, which in turn are enjoying 600w of lumen love. I now have a fixed panel on the car, and a controller under the bonnet, so the blankets wont see much action now at all really unless rooftop camping under trees .... unlike the van where having sun on the van is preferred, I choose to camp/camp in the shade because there nowhere to hide from the sun. In summary, for us blankets and portables rarely see much action
