Solar Power Goals
Safer than rigid solar panels, less liability: No wind uplift and drag rocking the vehicle, causing lower MPG. Less weight for better handling and MPG.
Best thin, flexible solar panels (long lasting, efficient, made in USA)
Most watts while not hanging off edge, allows both fan and sky light, allows future awning
Works in partial shade due to front and rear charge controllers, two entries
Mount with EternaBond so no screw holes that can leak, don't completely secure to allow air flow and water drain
Series MC4 cable connection recommended for simplicity, fewer parts, thinner wire and better for 24 / 48V battery bank.
If your roof is flat, use corrugated plastic under each panel to allow air flow cooling.
Reason mounted on the driver's side edge of roof is for easier cleaning access on one side, use of rail to fasten panels and frees up right side of roof for awning.
EternaBond extremely difficult to reposition or remove, just cut to move panel and re-tape over. Don't let edge of tape roll touch solar panel cells or sticky residue extremely hard to remove. Apply EternaBond in a clean, dry climate. Trying to apply when very humid or damp will result in wasting the tape as it will not stick.
Roof rail bolts and nuts should be stainless steel (expensive) or galvanized / zinc coated. If use table legs, remove felt, scrape smooth / level and use Gorilla glue to fasten to prepared level spot on roof.
Aluminum flat bar length for a 2007 to 2020 Sprinter van is 54" (from rail to rail).
2007 to 2020 Sprinter van (probably many others vans also) rail bolt is 5/16in-18 x 1 to 1.5in stainless steel or galvanized.
Use 3/8in galvanized / zinc flat washers, lock washers and 5/16-in stainless or galvanized nuts
Avoid silicone caulk because you can't paint it and no tape sticks to it. Avoid double sided tape to attach anything to the roof because it's made of cheap Chinese materials that will not retain adhesion.
Do use screws to fasten MC4 cable entry boxes, but use EternaBond tape around edges. You can remove MC4 cable ends for easy entry into box and roof holes and reattach upon entry of inside of vehicle.
Use EternaBond tape along the front of the front-most solar panel to eliminate wind drag and panel damage, but leave a small gap at the front corners for rain drain.
Flexible solar panels do scratch very easy, use new, clean cloth only.
Don't overlap edges of solar panels due to difficulty securing and shade over solar cells.
Don't fasten two panels with same grommet unless edges do not cause shade over any portion of solar cells.