Tracking solar accumulator
I began the tracking solar accumulator project in about 2007 in response to a list of needs on solarcooking.org
It is meant as a lower tech alternative to Scheffler solar kitchens. The Scheffler dish is on equatorial mount and it twists and contorts to maintain its parabolic shape at the correct distance from the focal point as the seasons progress. This dish is to remain the same size and simply rotate to achieve the same thing. I made the first working prototype in April 2008. This used a waterclock (a 'dripper tracker") to rotate the equatorial mount. This introduced me to a center of gravity problem. The center of gravity moved as I did the daily adjustments for seasonal changes in the path of the sun. This caused it to require more force to turn the thing at certain times of the day. So I abandoned the project until these problems could be solved. A solution came to me in 2010. 2 dishes on equatorial mount that counter rotate. as the season changes. This means that the center of gravity stays in the same place all year. Another problem was how to make a large parabolic dish reflector without too many cuts or wrinkles in the alu foil or mylar.. Magnar on solarcookers.ning provided an answer. Cone solar. An approximation of a parabolic dish made up of cones. A cone is curved and bent in only one direction which means you can have far fewer wrinkles in your parabolic dish shape. For some reason, everyone wants to make full dishes, even though half dishes will work just as well. I worked a bit on the cone solar to find an optimum way to cut a sheet of 8 ft by 4 ft corrugated plastic for a half dish. In September 2010 I made my first cone solar reflector (about 1.7 sq meters reflector area but there were some problems. (No more decent sunlight and how to keep it in shape? In June 2011 I reactivated the project and used bamboo screws and pieces of plastic to keep a relatively stiff parabolic shape.
I put the thing in a stand that I made by trial and error and that is the state of the project so far.
Successes for the project. I won a prize in an instructables competition for the clock based tracker, and I was asked to enter it in the art and science fair in Toronto. (But I did not win anything there). David Williams, and Magnar from Solarcookers.ning have been helpful. The trackers section of the solar cooking wiki was created (partly as a place to store my work) shortly after I made the dripper trackers and part of the project was featured on solarcooking.org news page a few years ago. (I forget which part)
There is a video log of my progress on http://www.youtube.com/user/gaiatechnician I think the project has been useful. It produced the "mechanical mathematician", dripper trackers, the dual dish idea, and the half parabolic dish cone solar. (Which uses the material pretty economically) Brian White [[File:]]]]Aiming the cone solar dish is easier than I expected. Just watch the shadow! ]]