Good point about the weight. What height van do you have? My 2016 144 high top has a max roof weight of 330lbs. 8 of those panels would come in at ~320lbs.....In case you haven't already considered it anything on the roof that approaches the width of the body at the lower sides or greater poses significant risk of hitting signs and other roadside poles. This is especially true on roads that have a bit of camber for drainage. I have had a number of close calls when parallel parking on city streets.
Also having the panels on the roof extend more than a few inches past the large radius curve tends to catch air especially with significant height above the roof. You may find that crosswinds may pose a significant problem.
Finally take the weight on your roof into consideration. Any weight up that high has a dramatic impact on Handling and roll performance. Adding 100 pounds of panels to the roof was extremely noticeable to me. I can imagine what that would be like at two or three times that weight.
Racks attached to the OEM roof rails are excluded from the 330lbs rating.Good point about the weight. What height van do you have? My 2016 144 high top has a max roof weight of 330lbs. 8 of those panels would come in at ~320lbs.....
I can ask those in the know.How much weight is allowed on the roof rails? I guess I had always interpreted it as a total.
Really interesting. I always assumed that the 330lbs rating for the high roof was for any weight on the roof.Racks attached to the OEM roof rails are excluded from the 330lbs rating.
That rating is for roof truss/panel loading. IE. between the OEM rail locations or under-framing.
As a reference point, I have one 300 watt panel and it is more than enough to recharge my previous nights usage within a few hours of sunlight. To understand my usage, I have 400 amp-hours of lithium battery, a 7 cubic foot fridge, an induction stove, two fan coils, and several large lighting circuits (two at roughly 20 amps). So the number of panels you are planning to install begs the question: are you electrifying the drivetrain or using this to charge some electric racing motorcycles? Because you have way more generation than you'll use without a load much greater than the typical Sprinter camper.
As for building your own roof rack, as others have said, it really does matter, but I agree that building with aluminum extrusions would be fairly easy and require no welding skills, just wrenching. If doing this, really think about your design and how to connect all of the pieces in a way that will create the right balance of strength, usability and weight. The key to weight, cost and usability is on the connections more than the overall design. Welding one as others have said is going to be a lot easier with square tubing than round, or bar. You can also bolt together square tubing or bar fairly easily and perhaps at a lower cost and greater functionality than bolting extrusions together.
I have a split unit 12vdc air condition unit I want to be able to power without a generator. I also have an induction cooker and electric water heater for the "unlimited" water supply for the shower. I want to be able to live off grind for at least a month at a time.What type of loads are you anticipating or equipment/devices are you running?