Retrofitting solar in a T1N Interstate

[toskeysam]

Lew, this is what you and I discussed earlier. If it turns out to be an issue, I will dump the polycrystalline panel.


Sent from my iPad using Airstream Forums

[LB_3]

I'm no solar expert but if you wire the panels in series it shouldn't matter if the voltages are different.

[lewster]

Originally Posted by LB_3

I'm no solar expert but if you wire the panels in series it shouldn't matter if the voltages are different.

Yes it will. It's similar to using two different types if batteries or ones of different age in the same battery bank.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[toskeysam]

My panels are in parallel, not series. A 12 volt system.....The voltage balance is important as Lew points out, especially with a MPPT controller.


Sent from my iPad using Airstream Forums

[toskeysam]

Sorry guys....seems we are getting off topic for the OP.


Sent from my iPad using Airstream Forums

[Protagonist]

Originally Posted by InterBlog

Re: solar in general - So how do owners of Interstates with existing solar systems clean their panels? I'm assuming this needs to be done routinely?

When I go to the Blue Beacon truck wash, they clean the roof— but once I forgot to close the roof vents first! Fortunately the only one that leaked was the one in the wet bath…

Other than that, I just let the periodic New Orleans thunderstorms take care of it, and they seem to do the job pretty well.

[InterBlog]

One of the three panels loosely dry-fit to get a feel for how the rail system ought to be designed. Not the best pic - taken after dark by me standing on the roof and holding my iPhone above my head.

At lower photo right, you can see a black device poking out from the edge of the fridge vent shroud... that's the "combiner box", where the wire run feeds downward into the coach.

In an unrelated event, our original Dometic 2351 fridge died and we just finished installing a replacement this evening. The timing of the death was auspicious, however, as with the old fridge ripped out, the wire could be run.

I'll publish a blog post with greater detail once we get the whole project finished.

[InterBlog]

Santa Claus brought the 80/20 frame pieces, stainless steel hardware, and even a new drill press. Perhaps most importantly, a bit of free time has come with the holidays, so we are making progress on this solar project. I'm starting a series of blog posts with details, but for now, here's a money shot of the completed 3-panel frame. Weight of this portion - 76 pounds, of which 42 pounds are the panels themselves.

[InterBlog]

Getting closer, and learning by doing: this is my husband's first-ever welding job. He bought me my own welder's helmet to encourage me to learn how to do it. My first reaction to watching him work was, holy cow, welding is harder than it looks. Maybe later.


Anyway, these are the clamps that will encircle the tubes of the T1N's roof rack and receive the 80/20 "downrods" which in turn support the panel framework. This weld-up was the most challenging step in this process thus far, and now that it's finished aside from final hole-drilling and the galvanizing coat, I'm hopeful that we will have solar panels on the roof soon.

[LB_3]

I was encouraging InterBlog to give the welder a try because she keeps commenting about bottle trees made from rebar and other industrial yard art projects of which I have little interest.

I found it challenging to get pretty welds when filling the gaps between the flat bars and the round clamps. It was pretty much 30 minutes of grinding for every 20 seconds of actual welding.

Hopefully I won't have any small small pieces or curves on my projects until I get a clue how to use my metal melter a little better.

[Boxster1971]

Nice work on the welding. The best part about welding is the more you do the better you get. I came across a great welding resource web site by a guy named Jody.
http://www.weldingtipsandtricks.com/

He has a lot of great videos the help improve your welding skills.

My latest welding project was making a pair of racks to mount four 6V batteries under my Interstate. Here is a photo of one before cleanup and painting.

[InterBlog]

Originally Posted by Boxster1971

Nice work on the welding. The best part about welding is the more you do the better you get. I came across a great welding resource web site by a guy named Jody.
http://www.weldingtipsandtricks.com/

He has a lot of great videos the help improve your welding skills.

My latest welding project was making a pair of racks to mount four 6V batteries under my Interstate. Here is a photo of one before cleanup and painting.

WOW - that is cool! Nice job!!

It's also an encouraging photo for me because we still want to make a custom hitch platform / basket / enclosure / cage for our Yeti cooler and your device is faintly reminiscent of what I had in mind in the way of general construction approach (I described the predicament over a year ago in this Airforums thread).

In fact that was my deciding factor in rendering spousal approval for the welder purchase. All in, a Stowaway costs the better part of a thousand bucks and it offers zippo zilch nada nothing in the way of break-in security (discussed on other threads). If we can use our welder to fabricate both the solar frame pieces and the future hitch device, then it has largely paid for itself at that point. It becomes easy to justify.

[InterBlog]

Some general and anecdotal perspective on corrosion as it relates to our solar project and also Airstreams generally, both motorhomes and trailers -

My husband insisted on treating the steel connectors I showed in the post-welding photo above. I whined about the extra time and effort this was taking, but his argument was that, if we didn't do this, we'd be left with a stainless OEM roof rack that wasn't rusting, an 80/20 aluminum solar frame that wasn't rusting, and steel connectors between the two that would rust as sure as the sun rises in the east, no matter what kind of paint we attempted to keep on them. And the visual appearance would be terrible as a result. So he contracted out for surface preparation (abrasive blasting) followed by zinc phosphating.

I sort of feel like I got my whining comeuppance today when this article appeared in Houston Chronicle describing our most famous art installation, which is Broken Obelisk at Rothko Chapel. It's perhaps the most important work we have in this city and the best expert conservators are trying to preserve it, but they can't keep the thing from rusting out in our climate. They tried to coat it, and it didn't work. They tried to foam it, and that didn't work (there are warnings on the trailer forms not to foam trailers because the process will trap condensation and promote corrosion). Maybe they next need to think about phosphating Broken Obelisk. Seriously.

The moral of the story is that corrosion is a massive challenge in a place like this. It requires extra preparation and patience, which is not always my strong suit. Sigh.

The lower thumbnail shows the connectors post-phosphating when I picked them up at the plater. They turned an interesting shade of matte gray.

[Protagonist]

Originally Posted by InterBlog

My husband insisted on treating the steel connectors I showed in the post-welding photo above. I whined about the extra time and effort this was taking, but his argument was that, if we didn't do this, we'd be left with a stainless OEM roof rack that wasn't rusting, an 80/20 aluminum solar frame that wasn't rusting, and steel connectors between the two that would rust as sure as the sun rises in the east, no matter what kind of paint we attempted to keep on them.

Aluminum is a sacrificial anode for any grade of steel, so galvanic corrosion would cause the aluminum to corrode (oxidize) as well. Rain or fog would serve as the electrolyte to complete the galvanic circuit.

To prevent this, you want some kind of gasket material in between the steel and aluminum so that there's no direct metal-to-metal contact. But you can't completely eliminate metal-to-metal contact between steel and aluminum, so you'll want to use aluminum fasteners, because the fasteners will be easier and cheaper to replace when they corrode than will the solar panel when it does.

[InterBlog]

Originally Posted by Protagonist

.. you want some kind of gasket material in between the steel and aluminum so that there's no direct metal-to-metal contact. ...

Correctamundo. We discussed this last night. I am partial to pieces of bicycle inner tube, but hubster fears that will be too thick. Experiments will be underway in the next several hours.

[Protagonist]

Originally Posted by InterBlog

Correctamundo. We discussed this last night. I am partial to pieces of bicycle inner tube, but hubster fears that will be too thick. Experiments will be underway in the next several hours.

Anything nonmetallic and nonconductive with decent weather resistance will work. It also helps if the material is slightly compressible because that will prevent gaps that can trap water if the metal parts haven't been lapped to provide a perfect fit. Bicycle inner tube should be just fine in that regard. Depending on how thin the material needs to be, a thinner alternative might be a cut-up plastic Ziploc freezer bag (which is thicker than the sandwich bags). Whatever you use, cut it slightly oversize, then trim to fit after installation.

[InterBlog]

Originally Posted by Protagonist

... a thinner alternative might be a cut-up plastic Ziploc freezer bag (which is thicker than the sandwich bags). Whatever you use, cut it slightly oversize, then trim to fit after installation.

My "thin and I actually have it on hand" idea was 3 mil or greater contractor trash bag, same stuff I use as sheaths for the rear doors when I leave them open overnight. I think the black plastic may be a bit more UV resistant.

[73shark]

Originally Posted by InterBlog

Some general and anecdotal perspective on corrosion as it relates to our solar project and also Airstreams generally, both motorhomes and trailers -

My husband insisted on treating the steel connectors I showed in the post-welding photo above. I whined about the extra time and effort this was taking, but his argument was that, if we didn't do this, we'd be left with a stainless OEM roof rack that wasn't rusting, an 80/20 aluminum solar frame that wasn't rusting, and steel connectors between the two that would rust as sure as the sun rises in the east, no matter what kind of paint we attempted to keep on them. And the visual appearance would be terrible as a result. So he contracted out for surface preparation (abrasive blasting) followed by zinc phosphating.

I sort of feel like I got my whining comeuppance today when this article appeared in Houston Chronicle describing our most famous art installation, which is Broken Obelisk at Rothko Chapel. It's perhaps the most important work we have in this city and the best expert conservators are trying to preserve it, but they can't keep the thing from rusting out in our climate. They tried to coat it, and it didn't work. They tried to foam it, and that didn't work (there are warnings on the trailer forms not to foam trailers because the process will trap condensation and promote corrosion). Maybe they next need to think about phosphating Broken Obelisk. Seriously.

The moral of the story is that corrosion is a massive challenge in a place like this. It requires extra preparation and patience, which is not always my strong suit. Sigh.

The lower thumbnail shows the connectors post-phosphating when I picked them up at the plater. They turned an interesting shade of matte gray.

What post-phosphating treatment is planned as phosphating is a prep like primer and is porous?

You could put a non-conductive anodize coating on the aluminum parts to both isolate them electrically and prevent oxidizing.

[InterBlog]

Originally Posted by 73shark

What post-phosphating treatment is planned as phosphating is a prep like primer and is porous?

You could put a non-conductive anodize coating on the aluminum parts to both isolate them electrically and prevent oxidizing.

(1) Good old fashioned coating. Rustoleum in this case, just to match it to the other components. Phosphating was the process recommended by the plater for if we wanted to coat without having the initial treatment create too thick of a build-up.

(2) 80/20 comes anodized. For what it costs, it should come gold-plated.

[73shark]

Yeah, I know the 80/20 is a bit pricey as I used it for the frame for my DIY 110" screen in the man cave.

The cut ends of the 80/20 will require something like zinc chromate paint tho.