I did a solar cooker on equatorial mount last year and used it to steam soil and boil weeds, to kill seeds and pests in them (could use them directly as mulch and they also rotted faster than uncooked weeds). Steamed soil was a lot more productive than ordinary soil too. It made a ball of light around a big stationary cooking pot, but it is probably better to use the typical focused light under the pot. I want to make a safer solar cooker than normal where the cook is not exposed to light accidentally flashing in their eyes. First off I made a 1/5 scale model, and it is surprising how well it worked. (I may add a light shield to the model and maybe a dehydrator model but perhaps I can go straight to the full scale. Next I will scale it up to approximately a 4ft by 4 ft reflector (1.4 m2 approximately) and maybe direct the heat into the bottom of of a big box cooker or big solar drier. I made the reflector from 3 reflective plastic plates from the dollar store and I used the cone method to make the approximation of a parabolic dish. So yeah, this one is for gardening at my place, to reduce the need to have compost and to use plant material immediately to grow plants instead of letting it compost for 3 to 9 months before it is usable. Also I hope to use it to cook and to dry herbs and fruit. What do you think? I also hope it will show aid agencies that this is a better safer option than traditional bowl shaped solar cookers where you have to bend over into the light to reach the food. I did win a prize on instructables for an earlier stage of the project, this however is a little more advanced, and hopefully a lot safer. Brian
interesting, the down fall is that you also kill the good bacteria in the soil.
From of mine had worked in a nursery, and they used Methyl Bromide to sterilize the soil from noxic pests and plants.
Yes, cooking plant material does assist in the break down of plant fiber.
As far as using it to dry herbs and fruits, you'll need to control the heat so you don't have the Maillard rection effect on your product. To help avoid this, you'll require air movement and temperature control. I would assume temperature control will be manual.
__________________
“ When people get what they want, they are often surprised when they get what they deserve " - James Wood
A simple way to control heat would be to use motorized venetian blinds to shade out part of the light reaching the lens. Easy to add a control loop to and program for a set temperature. The power for running the fans, motors and controller could be solar cell derived.
__________________
"A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
Back in the days when I was a kid, I remember my grandfather had a large enamel pail he used to set on the gas cooker and cook the soil in it which he used in his greenhouse for the Tomato & Cucumber plants.
He also had a regular compost heap which he used to put earth worms in, which I found very useful for when I went fishing I had a free bait supply.
__________________
"A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
Neat. I live in the tropics, so the angles in the chassis of my version (latitude 8° north) would be different. Any link to the details of the project?
Yes, your mount will be almost horizontal, 8 degrees, pointing at the north star. (In line with the earths axis). I will do another instructable for the 2025 experiments and of how to do cone solar from a drawing board but this is the one to use for now. https://www.instructables.com/Tracking-Solar-Cooker-Project-2023-and-2024-Achiev/
This is a really old video, it gives an idea how the 2 dishes in the tropics might work. Another way would be to have hold an axle in the middle between the 2 dishes. (So more like how my current system is held but with a dish on both ends). This doesn't work so well where I live because the angle makes things difficult. The advantage of having 2 dishes like this is that when you balance your system, it's only once, because any seasonal movement up by one dish is balanced by the seasonal movement down by the other dish.
I just need sensors to operate an air valve. (Haven't found one yet) My version is rotated by a waterwheel, the air valve lets low pressure air to an airlift pump and that turns the waterwheel on and off. So, if anyone has suggestions for a sensor that turns on and off an air valve, it would be great! The system uses just a tiny amount of air and the air (for multiple parabolic dishes if you want) can come from a 20 dollar aquarium bubble pump.
Why don't you use a Low Air Pressure switch from a Air Compressoer ? When the pressure drops to a preset limit the Switch activates (Ajustable switches are available) and turns the pump on.
Or possibly look at some Low Pressure switches from cars, like the Air Induction sensor or the ECR VAlve sensor etc.
Sounds like a fluid logic application. Maybe a search under that term would pull up something useful. Back in the heyday of fluid logic, control signals in the one-thousandth of a pound per square inch (guage) were used successfully, and power supply pressures of less than 3 psi.
That would be nice, I think at my latitude it would be a matter of putting the focus at the other end, and guiding the machine and reflector across the field to move the hot spot along as soon the weeds get killed. You won't be able to kill them all, but maybe an area about a foot wide along a drill. It is probably more efficient to use solar panels to run little mini cultivators in that case, maybe harvest the little weeds and steam them to make their nutrients almost immediately available to the plants you are actually growing (instead of waiting for them to rot in place)
__________________
"A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
__________________
"A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
Lots of sources, sizes and prices online. Google Fresnel Lens for more.
__________________
"A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
Years ago I read about a contest to design the simplest, easiest to ship parabolic reflector for 3rd world countries without a lot of technology. The winner was a sheet of reflective metal, with a spiral cut from the center outward, that could be easily shaped to a wooden (locally provided ) parabolic shape .It could be shipped flat, and installed just about anywhere with unskilled labor .A pattern for the frame was shipped with each dish to construct the form.
You could try this yourself for an easier way.
__________________
"A man never stands so tall as when he stoops to help a child." "Never argue with a stupid person.They will drag you down to their level and beat you with experience" "To create an apple pie from scratch, first you must create a universe"
Yes, I am making the first pattern to cut from a sheet of chloroplast corrugated plastic or sheet metal. (I used chloroplast last year but I wasn't thinking straight and I didn't make the dish parabolic because I was afraid of burning stuff like food, eyes and my back yard. It was designed to make a ball of light. This new one produces much more concentrated light. The picture is the old pattern from last year. For the new one, I am still working out the pattern. I want an exact 4 ft by 4 ft parabolic dish, (just easier to compare it with existing parabolic dishes because that works out to about 1.4 sq meters. This pattern is 55 inches wide though, so its tricky to fit it in a 4 by 8 sheet. It might be that I can use some of the left over corrugated plastic as "ribs" to hold the parabolic shape. The old one had 11 strips, the new one will have 8, so less cuts! I used "Tuck Tape" to hold it together. Nothing else worked.
I got the full sized reflector built yesterday, then I had to modify the equatorial mount a bit, and finally got to burning stuff around 5 pm. I used 1/8 inch white ABS sheet 8ft by 4 ft to make it. About 5 ft by 4 ft was used to make the reflector, this was slightly smaller that the 1.5 sq meters I had intended but it meant a lot less waste. (to get the perfect 1.5 sq meter size, you need to go to about 4ft 3 inches wide, meaning some of your arcs would be going from side to side instead of all lengthways. Lose the few extra inches, and everything is easier, plus you a 3 ft by 4 ft waste piece and it is enough for a second smaller solar cooker of about 1 sq meter size! The ABS material is slightly too bendy but at least it is nice and smooth on the surface. Burning wood is a bit silly but at least it shows that it concentrates light. Earlier today, I fried an egg. I "slow fried" the egg (took 5 minutes) as I missed the pan but heated the handle. Later when I was checking stuff out I discovered that my equatorial mount was set to 42 degrees instead of 48 degrees. (it spreads out the focal area and that helped explain my trouble frying an egg). And I put aimers on the side boards so I can aim the darn thing exactly at the sun. (exact aiming also tightens up the focus) My first solar fried egg tasted great but I'm pretty sure the experience of cooking the next one will be a whole lot nicer and quicker and less burny. Anyways, the experiment looked a whole lot different this afternoon than it did yesterday. The video is from yesterday.
Here is the latest version. I am hoping to make a big insulated box (essentially a box cooker) to go over and around the pot. It will have a door on the back and a very short tube low at the front to let in the concentrated light from the parabolic.
The box will be something like the drawing, letting in the light and heat from the bottom, and hopefully not letting it out and hopefully the glass lid doesn't break.
Safer, Simpler Solar Cooker/Solar Drier? 
Re: Safer Simpler solar cooker/solar drier?
"Almost" Good Answers: