Sunday, April 11, 2010

Constructing a Solar Pod

The Solar Pod has already proven to be far more complicated than the Solar Cones were. Last weekend my friend Steve came down to help me start assembling the pod, and we had the basic structure complete by the end of the day. I use the term "complete" loosely as we were far from perfect in our construction of the end plates, which really are the most difficult part of the assembly. Curves are hard.

The template in the book provides only the most basic of information. We had to do a lot of our own measuring and marking on the template to figure out the actual distances along the curve, and we made multiple mistakes along the way. It took us a long time to get to the point where we could cut out the first end plate.

In this shot you can clearly see the tangle of measurement lines. We luckily Steve knew which one to follow.

Once both end plates were cut out we went on to sanding them down to match our measurements. After this we stacked both end plates on top of each other and clamped them down tight. This let us sand them down to the point where they roughly matched each other, to allow the fiberglass sheet to rest smoothly across the length of the Solar Pod.

Now when I say we made the curve smooth, I mean we made the curve sort of smooth in a wavy sort of way. The end plates pictured above have the spacer attached and you can clearly see the curve is imperfect on the inside part of the arc. Luckily the imperfections haven't been insurmountable.

Gabe was really interested in what we were doing and pitched in to help whenever he could. He really loved the right angle ruler.

Here Gabe tied to pick up the ruler while standing on it. This did not work.

Despite all of the setbacks we still managed to assemble the basic structure by the end of the day. Once we deemed the end plates "good enough for government work" assembling the rest was rather simple by comparison. The plans recommend cutting the 2x4x8s down a couple inches, but since the fiberglass panes were larger than spec we didn't and it made no difference later on.

With some help from Michelle placing the glazing down onto the silicone caulk, the process of drilling and screwing the inner glazing down was really straight forward. I cut it to 96" long instead of the 94 1/2 the directions recommended, and I had to trim an inch off the width due to our imperfect curve. Still, once it was cut to size it attached seamlessly despite the wavy curve.

You can see in this shot that the Solar Pod is not particularly tall. I'm already certain that I'm going to have to build at least one of the drop bases for it, if not one of the permanent insulated bases, in order to give the plants under it enough space to grow up.

If I had thought about it I would have stained the wood long before we started assembling it, and certainly before the inner glazing was on, but I was so unsure as to whether I'd get this far that it just seemed overly optimistic to do so. Even with the glazing on, however, it was pretty easy to stain the wood. Any I got on the glazing wiped away clean.

The pink insulation was easy to cut with a high tooth count jigsaw blade. We had used the wood endplate pieces to draw out the shape before we assembled them and it meant the insulation fit like a glove. Yay for small successes.

The conduit piping is what ended the day for me. The instructions call for 3/4" conduit piping for the middle, to provide support to the glazing under a heavy blanket of snow - and that's what I bought. However, 3/4" conduit piping means a 3/4 diameter hole inside of the pipe, but the plans only make sense for piping that is actually 3/4" diameter. The diagram also fails to specify what length of piping to use.

Overall, the instructions for the Solar Pod are clear. The end plates were the biggest problem for us, and if you have a better method for drawing the proper arch shape onto the wood then you would probably find the whole project much easier than I did.

If all goes well I hope to complete the pod next weekend.


Doctor Mom said...

Very impressive! Can't wait to see how your creation does.

Jen O. said...

Now that the gardening season is waning (or maybe that is just where I live!), I am curious about your experience with the solar pod. Also, how wide is your solar pod? What materials did you use for the top? Do you think its worth the effort?


Michelle said...

Hi Jen! Sorry we were slow to approve your comment. I'll let Chris know that you are asking about his solar pod. I'm not sure if he will be able to tell you yet whether it was worth the effort, since we haven't tested it over a winter yet.


thom said...

Very impressive. I am failing the IQ test when assembling ours. 1. Did you determine the radius of the circle which describes the arc of the end pieces? 2.What did you use as conduit material? If metal, did you make a template to form it? We have a spiffy set of raised beds and hope to continue generating stuff for the kitchen. This project is taking some of the taste from that idea.
Let me hear from you.