SOLAR PANEL INSTALLATION, PART 2: EXTERIOR COMPONENTS

In the first part of this post series, I talked about our rationale for DIYing a larger-capacity solar system in our 2007 Airstream Interstate T1N Mercedes Sprinter-based Class B RV.

In this post I will describe the principal external components and the general approach to this job.  I'm not going to include precise measurements or detailed instructions because (1) installation principles have already been described by others, especially the solar equipment vendors, and (2) we may be the only T1N Interstate owners on the planet who choose this particular solar array and installation strategy, and therefore it's not worth it for me to over-do the details.  There are easier ways to do this type of project, and there certainly are cheaper ways.  If any reader does decide they want more information on this exact installation, please contact me via interstate.blog -at- gmail and we will chat.

So here goes my attempt at giving a general orientation and a "feel" for the project.

As explained in the first post, our plan was to use the high-quality but functionally useless OEM roof rack that Airstream installed on the T1N Interstates.  Here you can see that both the air conditioner and the Fantastic are higher than the rails, so this requires a vaulting system for the panels.   

For the panels themselves, we chose a Grape Solar model called GS-S-100-TS.

Tap to expand for clarity. I'm adding this excerpt from the technical data sheet (PDF link) to distinguish this panel from other models, some of which appear similar but are lower efficiency and different construction (and less expensive).  

Here is what one of the 3 panels looks like when "dry fit" framelessly in the intended space:

By coincidence, these panels were exactly as wide as the rails, literally to within millimeters.  Photo taken by me standing on the roof.  You can see my husband to photo right, standing on the Telesteps 1400 E ladder that we keep in our Interstate.  

We bought 3 of these panels and other components to be described from a small company called AM Solar.

I think they were happy to receive our rather large order.  These photos are from the packing materials.  

We decided to run the wiring for the panels down through the propane refrigerator vent.  AM Solar sells what is called a Refrigerator Vent C-Box (with the "C" standing for "combiner") for exactly this type of retrofit.

Tap to expand for clarity.  This is a simple diagram that will be reflected in the next few photos to follow.
Thanks to Dave's Place for the base image.

My husband bought this type of wiring from Lowes, but recommends to other DIYers that it would be better to get a similarly spec'd wire with a larger number of thinner strands.  The wire he bought was available locally but was stiff and challenging to work with.

Here is the installed combiner box with the cap off, shown penetrating the side of the fridge roof vent.  

Cap on. 

Screen replaced on vent, but rain shroud not yet in place.  Note that there is an elbow conduit visible just to the right of photo center.  That part did not come with the combiner box - my husband added it to protect the wire.  

Wire then comes down through the fridge cavity and proceeds below the cavity floor (we did this part of the installation while replacing our Dometic 2351 refrigerator which is described in this post).  The solar panel wire is zip-tied to the existing bundle to keep it from interfering with the fridge.  

Here's where things get more interesting and non-standard.  Because we were mounting these 3 panels on the OEM roof rack, we could not use conventional hardware such as what is shown in this photo which I screengrabbed from this Roadtreking blog entry.

Gosh this makes me nervous! Those tiny little adhesive feet and those tiny little panel clamps! It looks so flimsy to my untrained eye!  But I've never once read an account of a solar panel flying off a roof and landing on a highway, so my durability fears would seem to be unfounded.  

Of course, that particular Class B poster had no roof air conditioner to contend with, a scenario that would make any Houstonian faint dead away with shock.

Here's a closer view of a conventional attachment mechanism for direct on-roof placement, photo screengrabbed from this forum thread.  I believe that some folks use only adhesive - no screws. 

We decided to build a frame out of a versatile extruded aluminum product called 80/20, which tag-lines itself as "the industrial erector set".  The next series of pics shows how those components go together.

You've heard the adage "measure twice, cut once"?  Well, with this expensive 80/20, I suggest measuring fifteen times before placing your order.  My husband got the order exactly right on his first try, but it took him many hours of pondering and calculating before he pressed the "buy" button.

Here you see the general arrangement of the support rails.  The center gap is larger for maximum air conditioner clearance.  We wanted the panels to be vaulted above the a/c, but no more than necessary, in order to minimize the degree of wind that the panels would catch and the degree to which we would affect the vehicle's center of gravity.

We used our drill press to punch new holes in the Grape Solar panel frames for our non-standard attachment to the 80/20.  A hand-held drill would have posed a risk of punching through the glass panels themselves. 

The panels attach to the 80/20 rails using these stainless steel assemblages.  The "tongue" slides into the slots in the 80/20. 

This is a cross section, so that you can see what I mean by "slots".  

Every part of the 80/20 system goes together with its own special hardware. 

It takes a special tool to reach in there and tighten.  

Close-up of one part sliding into another. The end is threaded so that a protective cap can be screwed on. 

There's the finished assemblage, back side, with everything tightened up.  

Front side view.  

In my next post, I'll talk about how the clamps and risers are attached to the OEM roof rack.  That post may be a bit more time in coming, because we still have to weld receivers for the risers onto the cylindrical clamps that attach to the roof rack.