Solar and max fan upgrade to Big Blue


New member
After reporting on my a/c mishap last month I have got a lot of #59’s issues fixed. Using a tractor to remove the,(very heavy) a/c unit I was left with a 15”x25” hole. Using marine grade polymer sheet I covered the hole with butyl bedding and screws, then cut the 14”x14” hole.
Next I installed the max air 4500 with a remote control panel and a solar cable inlet port. Then sealed it all with self leveling rv sealant.
Using the 6 mounting points for the a/c I added 2 aluminum tubes to attach a 170watt sun power flex solar panel to the roof not adding any new holes. The end result is very sturdy and off the roof to aid in airflow.
I made a bracket to mount the mppt controler and ran the cables through where the cig lighter was.
I left all the a/c stuff in place, if someone down the road wants a 12v a/c it can easily be converted back to stock.
This system has the benefit of providing a bath exhaust fan, just open the high access over the door and crank it up.
some new wheel covers with benz inserts and big blue is ready to go. PS is old a/c unit has been claimed by another westy owner.


2004 T1N Westfalia
Thanks. Excellent info. If you have time, more specific info on brand/size/etc., on polymer sheet, alumin tubes, controller, etc., would be great.

Some additional info/thoughts:

1. Use of Aluminum Tubes. Very clever to reuse AC mounting points. Also, besides air cooling, the elevation allows clearance for the upper kitchen cabinet mushroom vent (replaced with lower profile?) And the pre-drilled mounting holes (plastic covers) are not covered (clearance space around holes too) so can add the kayak/surfboard brackets for whatever purpose.

Also allows easy replacement of solar panels in the future.

Idea: One could modify this set up for a portable one by using the same type tubes but using some type of easy to remove brackets. This would save wear and tear on the solar panels. A combination of sliding brackets and thumbscrews so can reach from skylight?

2. Sunpower 170 watt panel is 45.4" x 31.9" (confirm to be sure)--so you can see the size fit on the roof.

A more rigid backing would be used to reduce flex and cracking of solar panel on the aluminum tubes.

A matching voltage solar controller is needed as the 170 watt Sunpower panel is a higher voltage. Most controllers have ability to step down higher voltage panel to right charging voltage for 12 volt batteries.
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New member
Thanks for the kind words. Being a retired building contractor I really enjoyed thinking through a completing this project. I figured the whole solar setup for a 5 year lifespan. (The warranty on the sun power 170w panel).

I mounted the max air fan on a 1/4” thick piece of starboard from taco marine, a polymer “plastic wood” that will outlast the van.

The aluminum tubes were hardware store items in a rack with different size and shapes, nothing special, 48” long. Stainless hardware and lexel sealant in the holes.
Attached to the rails is a piece of 3/8” ac plywood cut to exact size of panel, painted 2 coats exterior finish, attached with #12x1” sheet metal screws 4” on center. On top of ply is a piece of corrugated plastic from the sign shop then the panel. When I screwed down the ply I added a piece of closed cell pipe insulator on center to create a slight bow to pitch water to the sides. then I through bolted through the grommets in the panel.
next I wrapped it all together with rv sealant tape cut to 3” wide, this stuff is amazing, it really sticks. Then sealed the corners with self leveling rv sealant.

I canabalized the vent to make it flat. My first attempt was to stick the panel to the roof as described in the boss solar video. I didn’t like the way it looked so I went back to the raised method with the tubes. I found a vent that is low profile and it will be installed soon.

As for the controller I am happy with the rich solar 20amp mppt. Is is identical to the renogy model and a little cheaper. It came right up working with little programming. It has a very low self consumption rate and can handle an additional panel if I decide to add 100w to the nose cone.

I thought about a portable panel but I really liked the idea of the batteries always being topped off when the van is just sitting not being used, it now feels like I can forget about the whole thing an jump in and go.

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