SOLAR PANEL INSTALLATION, PART 1: PREAMBLE

Our 2007 Airstream Interstate Class B T1N Sprinter-based RV was born without a solar energy installation for recharging our house battery (newer models have multiple batteries but our original configuration only had one Lifeline).  After a year of ownership and about a dozen in-state overnight trips, with our forays being limited by our family responsibilities and employment schedules, we decided that we wanted to go ahead and DIY a solar system.  We knew it would be a big job that would take some time, but our long-range plan is for more elaborate off-grid trips, and we want to be ready when that time comes.

Because gosh knows that I have very little regard for staying in campgrounds.  Hookups are nice, but there's a terrible experiential price to be paid for those conveniences, as I explained near the end of this post.  And the generator is good to have for emergencies and short-term uses, but I don't want to be deafened by it when I should be enjoying the great peaceful outdoors.  

As far as we know, our plans in this regard were unprecedented.  Neither my husband nor I had seen an existing example of a T1N Interstate with a retrofitted solar system, either in the resale market or on Air Forums.  With the amount of work and expense associated with this job, we did extensive research on what would be the best way to accomplish our goals.  Here are a few sources from which we gleaned our concept-level information.

1. Without question, Handy Bob's elaborate solar power diatribes are the best on the internet, especially this one which describes some common pitfalls associated with both DIY and professional RV installations.
2. We were well-cautioned by the seemingly endless solar-related thread-hatching on Air Forums.  As of the date of this blog post, I can safely report that there is not another system on the Interstate that causes as much angst for owners as the battery maintenance, which in most model years hinges primarily on the efficacy of the vehicle's corresponding solar system.  You can read this thread and this thread and this thread and this thread and still not even remotely be done with the conversation as it relates to Airstream's solar installations, electricity management hardware, accidental coach battery ruination risks, parasitic system draws, the emerging potential for lithium battery upgrades, and other facets of this complex issue.  
3. In our research, we also encountered some anecdotal reports that influenced our decision tree.  This Roadtreking post subtitled "Adding Solar to an Older Class B" was among the useful vehicle-specific sources we found.  

One theme that persisted across many different accounts was the need to over-design the solar system.  In theory, you calculate X amount of demand and so you install X amount of solar capacity and you're done.  In practice, you calculate X amount of demand and then proceed to install perhaps as much as 2X or 3X capacity in order to be responsive to systemic inefficiencies, unforeseen circumstances, unavoidable parasitic draws, and other logistical limitations.

Given my desire to use our Interstate as a mobile personal workstation, my future electricity demands could be higher than those of the average vacationer.  For that reason, one of the first big questions that we had to address was where to put multiple solar panels on the roof of our T1N Sprinter-based Interstate.  The available space is small and there were already multiple pieces of equipment installed up there, including a Dometic air conditioner, a Fantastic roof vent along with its cover, propane fridge vent, digital OTA TV antenna, cab radio antenna, back-up video camera, extra brake lights... all that on the roof of a 22-foot camper van.  And remember Handy Bob's number one solar lesson - nothing can cast a shadow on the panels because any interference whatsoever will cause the systemic efficiency to plummet.

One of Handy Bob's no-no's, screengrabbed and annotated from this post.  Tiny shadows can scuttle the efficiency of the entire system, but many owners and installers are either unaware of this, or in denial regarding it.

I took my solar installation inspiration from this startling T1N Interstate photo that appeared in the resale market in mid-2015.

Holy crap!!  How did those owners get those kayaks on and off that roof?!

The genius in that kayak mounting example was that the owner(s) installed a second roof rack on top of the existing OEM roof rack, thus making that section of the roof do double-duty in supporting both the air conditioning unit and the cargo vaulted above it.   And if they could successfully do this with big bulky kayaks, surely we could do it with solar panels.  Right?

The OEM Airstream-installed "roof rack" on the first generation of Interstates is an odd contraption.  It is simultaneously the highest quality and most useless appurtenance that Airstream elected to add to the T1N Sprinter.  It is made out of high-quality stainless steel tubing that shows incredibly tight tolerances - how does a diameter of 2.001 inches sound in terms of precision manufacturing?  Where did Airstream get this stuff??  And yet in its original form, it is good for pretty much nothing, because both the Fantastic and the Dometic air conditioner protrude into the space above it, preventing anything from being placed on it.  

Such an expensive piece of hardware ought to serve a purpose other than merely decorative, which may have been Airstream's intent given the corresponding physical limitations described in the photo caption above.  In my next series of posts, I'll talk about the strategies for maximizing the utility of this device, and the installation of our solar system components.