The Sun Scoop Tracking Solar Cooker!

I made a tracking solar cooker, it's almost 1.5 sq meters in reflector size. It is a section of a parabolic dish, and it will allow the user to reach what you are cooking without moving the reflector or putting your eyes into dangerous levels of light rays. It is on equatorial mount so that as long as you point it at the sun in the morning and rotate it slowly at 15 degrees per hour, it will stay pointed at the sun all day.

Scissors, saw, drill, compass dividers protractor pencils, drawing board, drawing paper, 8 ft by 4 ft sheet material (ABS or corrugated plastic, like chloroplast), wood in 2 by 4 and 2 by 8 sizes, pots and pans, rebar, wood screws in various sizes, specular reflective tape.

I Went for a 15 cm (about 6 inch) diameter target where all the rays would come together as a ball of light. (I used a 1 to 5 scale so a circle of 15 cm was actually 3 cm wide). I drew a circle of 15 cm diameter for the target, then from the right edge of the target I drew 9 vertical lines 15 cm apart. Between the lines represents 15 cm vertical shafts of light. I then made horizontal lines from the top and bottom of the 15 cm ball. Where the top line intersects the last vertical line and the bottom line intersects the second-last vertical line are the ends of the first "mirror strip" of the parabolic dish. To get the ends of the next mirror strip, you draw a line from the bottom of the first mirror strip to the top of the target ball, and you draw a parallel line from the bottom of the ball to the 3rd vertical line, Where it intersects the 3rd vertical line is the end of the second mirror strip. You continue with this method until you have your 8 mirrors drawn. Next you draw a vertical line down from the center of the target ball to the bottom of the page. A line continued from the first mirror strip will intercept that line. Measure its length to both ends of the mirror strip and write them down, do this with all the other mirror strips too. These are the radii of the strips of plastic or metal that you will cut for your reflector!

I used a 4 ft by 8 ft sheet of 1/8 inch thick ABS plastic because it has a very smooth surface. (I could have used much cheaper corrugated plastic but it has a slightly "wavy" surface and that will spread the light in unknown ways. This is the "prototype" so I couldn't take the risk of using suspect material. (Corrugated plastic might be good enough). Anyway, i drew a line down the middle, 2 ft in from each side. I put the center mark for the first curved strip at the correct distance from the far edge, Then marked it at the edge of the plastic, then from the same center make the next arc of the circle. This is the bottom edge of your strip. Next, from where the bottom arc meets the center line, measure off the distance from the outer edge of the second mirror strip on you diagram and that is your next center point. Do you 2 arcs again, and continue the process with the next mirror strip till you are done. When I came to my last center point, I just drew a line from there across my plastic sheet and cut off the "waste piece" to use later for another project. This project uses approximately 5 ft by 4 ft of the plastic sheet. Next I cut the arcs, and ended up with pile of 8 arcs and a small pile of cuts from between the arcs. After that, I pulled the arcs tightly together and taped them together with TucTape. Nothing else worked last year, all the other tapes allowed the material to pull apart, so I went with the proven Tuctape. After that, I glued on the reflective material.

I made the frame last year for my previous solar project and this year I just modified and extended it to take the bigger reflector.

I ended up putting up a temporary frame on the side to hold the pot. That way, I have good access to the pot.

I fried an egg (before I had things leveled properly, so it went to one side). After that I was steaming grass to use as mulch, (and potentially as mushroom substrate). I will also be steaming soil to kill bugs, seeds and diseases in the soil. That worked great last year. This year, its faster and the pots are bigger so I will get more done.

I want to build a "box cooker" that is big enough to hold my biggest pot. It will go on the stand, and I will have access via a door at the back. The sunlight will come in through a glass lid at the bottom front and hopefully a lot of heat will be trapped inside. I am hopeful that this will increase the capabilities of the solar cooker by a large factor. I also plan to have the box cooker double as a solar dehydrator or have a separate solar dehydrator that I can put on instead of the box. so it will be like having attachments.

I hope that in a few years, solar cooker manufacturers across the world will be making these thing with nice metal frames and in various sides. (It depends on the materials they have available). And also, the size of my reflector is similar in size and shape to that of a car bonnet or hood. So, maybe in a few years, industrial companies will stamp out "bonnet" reflectors and "hood" reflectors from metal blanks while others will be making them in fiberglass and in plastic. The industrial production can have much tighter focuses than mine, so they can probably send heat through a tiny hole into a box, meaning they can transfer more heat, while letting less out. So yeah, hopefully the future can be mighty!