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Solar oven project update

Posted by admin on Sep 29th, 2008
2008
Sep 29

I started cutting out the frame of the new solar oven from scrap plywood laying around in the garage this past weekend. I have all of the sides cut out and ready for assembly, I just need to find my wood dowel pins to put the pieces together and I need to find a scrap piece of wood big enough for the bottom. I had to make the sides in two pieces because I didn’t have anything left that was big enough to make it solid. Here’s what I have so far:





The top of the sides are set at a 30 degree angle – I had read that is the optimal angle for solar panels somewhere. Once I locate my dowel pins and find a piece for the bottom then it should go together fairly quickly.


Here’s a picture of the one I built last summer. It’s got an old window I found in our garage from some previous owner, and it works pretty well. It’s lined with foil and the bricks in the bottom are to help keep the temperature a little more even. The test I did with it yesterday got it up to over 170 degrees. If it was built a little better and all the gaps and holes sealed up then I might be able to get it hot enough to boil water. I’ll be adding reflector flaps to the new one to ensure it will get more than hot enough for that. It currently sits on an old skateboard for portability, because with the bricks it’s quite heavy:


Does window efficiency film work?

Posted by admin on Sep 29th, 2008
2008
Sep 29

About two weeks ago I wrote that I was going to try to make our single paned windows in our home more energy efficient by using a window film that claims to block around 70% of the suns radiant heat. This weekend I finally completed enough of the project to get an idea on if I’m heading in the right direction. It seems that I might just have wasted my time and money on this.


Of the 12 “panes” on the window, I put the film on 11 of them. I left the top middle pane untouched so I could test the difference in temperature between the filmed and non-filmed sections. I went to Harbor Freight to pick up a cheap infra-red thermometer ($10 – and I plan to use it around the house to find hot and cold spots). Since it was doing the testing on glass, I wanted to make sure it wasn’t skewing the test results when I checked the window temperature so I first put a large washer on the two test panes (the top left pane and the top middle pane) and checked the temp. Hmm – 106 degrees for the non-filmed pane, and 104 degrees for the filmed pane. Whoa.


Okay, maybe the metal washer is making a difference. I decided to put a paper mailing label on each window – that way I would have a surface to test that wouldn’t potentially accumulate heat due to the material it is made from. It did make a difference, the temperatures dropped about 5 degrees for each pane, but they were still 2 degrees apart. The filmed pane was 99.3 degrees and the non-filmed was 101.3.


That’s very disappointing. I’m going to double check the directions, and look for some tips online from others who may have tried the film and see if they have any suggestions on what the problem might be. If I can’t find that I’ve done something wrong then I’ll start looking for alternate ideas to make the windows more efficient.