READ HERE: I’ve made a video previously with just drawings about this, but here is a quick model of that.
Each array system has it’s good and bad points. It helps in any mirror array system if the focus is direclty inline or as close as possible with the Sun (as commonly used with the parabola/dish type systems). It will then be more efficient at using the sunlight and it will collect more energy. This system shown in the video is perhaps the cheapest and simplest to make. If it is not so efficient at gathering enough energy at certain times/angles, then more collector (mirrors) surface area will be needed….so design it for maby 1.5 times larger than needed….for example, instead of a 1,000W system (a square meter total area), design it for a 1,500W (a square and a half meter total area) system.
The mirror shown in the video is about 3.5 inches on each side. I think 3 to 4 inches is good (for heating a single pot or pan, however more than that may be needed for a large solar oven for baking), and any more than that, then the system starts to get too large if the same number of mirrors are to be used. This is a recycled mirror, about 3/32 inch thick (about 2.4 mm), from a bathroom “medicine” cabinet mirror. I have a video up about basic glass cutting.
The white base part below the mirror, as seen in the video, is just a segment of a pvc pipe (1.25 inch inside diameter). It’s cut at 90 degrees relative to the sides of the pipe, however a small cut near the edge of the semi-sphere will allow the mirror to be tilted some more degrees. A level cut (not the “flat” 90 degrees) can also be used at the base of the pipe for setting mirror angles.
I guess its good “match” the semi-sphere and cylinder. You want the mirror to tilt as much as possible, however thats when the semi-sphere is sitting minimally on the cylinder. There is more support when the semi-sphere is glued in deeper; maby try for maby 1/4 of the sphere diameter.
The plaster semi-sphere has a diameter of about 1.5 inches. I got the plaster from the local hardware store ( i think it says it has some binder/glue in the mix too, but I think “dental plaster” is much harder – probably as hard as baked clay/brick before the glass/ceramic stage) Allow it to dry completely. It will be a grey color when wet/damp, and then will turn white when dry. When dry, you can put a thin coating of glue or something like epoxy on it to prevent it from absorbing excessive moisture, and to add a bit of strength to it.
This system I have in mind here is not a traditional heliostat with motor steering, but one of manual/hand steering. This is for simplicity and cost.
I’m thinking of a focus of concentrated energy at about 8 to 10 feet from the mirrors. The farther the focus is from he mirrors, then the less the mirrors need to be “angled” or adjusted, so maby the semi-sphere idea is not even needed. All this is more or less still on the “drawing board”, so give it a try if you want results now.
When I cut this square mirror from a larger mirror, I tried to just cut and remove that small mirror right out of the larger mirror. This is not recomented I guess now because it has a tendancy to not break where you want it, giving extra or less pieces of glass usually. So then, try to cut/score entirely across the large mirror when cutting, and then work with the smaller mirror/piece to get the square piece.
As mentioned, I put a glue or waterproof epoxy coating on the back of the mirror (after the semi-sphere was glued on) to give a layer of protection to the silver of the mirror. Cloth can also be set into that clue to prevent the mirror from shattering all over if it gets broken. You can also try some regular paint you have laying around on the back of the mirror.
Post time: Jan-12-2017