Anyone who grows their own fruits and vegetables will face this problem: what to do when seasonal production exceeds consumption? One possibility to preserve the product and use it throughout the year is to dehydrate it, an option that allows the nutrients to be preserved. An alternative to be able to apply this technique without having to invest in market equipment or increase electricity consumption is to manufacture a dehydrator that also works with energy captured from the sun.
The concept is simpler than it looks: circulate hot air over finely chopped food. The warmer the air, the more effective the system will be at removing moisture from the fruit or vegetable. Now, be careful, because too much air can end up taking you where you don’t want it; until the temperature drops and the system is no longer operational. Therefore, if you follow these steps, you will get exactly what you need to dehydrate your food quickly and efficiently.
Contents
Materials and tools to build a solar dehydrator.
To get started, make sure your tools include a soldering iron, hacksaw and wood saw, scissors, ruler, square, drill, and utility knife or box cutter.
Once you have all of this, the materials you will need are:
- About 12 meters of square tube.
- A sheet about five meters long and a little less than a meter wide.
- A 0.6 x 2.4 meter polycarbonate greenhouse panel.
- A pair of hinges.
- A closing.
- Silicone.
- 11 wooden boards 2.4 meters long.
- A screen for securing food approximately 5 meters long by 0.6 wide.
- Two beautiful wooden molds.
- Wood screws and self-tapping screws for metal.
Instructions.
First step: build the frame.
The size of the frame will be whatever you decide, although in this example we’ve chosen one that’s just over a meter long (1’2) and just under half a meter wide (0 ’48).
Following these measurements, for the horizontal structure, cut three pieces of square tube of 1.1 meters and two others, in this case a little longer, of 1.2. For his part, for the vertical, he extracts four other pieces of the tube, two of 0.8 meters and two others of about half a meter.
At this point, assembly will begin. To do this, place the two 0’8 pieces on a flat surface. Mark each one, first 3 inches from the bottom, then about 10 inches from the top. Now, between the two bars and just at the first mark (the 7.5 centimeter mark), place one of the 1.2 meter ones you had and solder them. Repeat, now at the top end mark. With this you will have the front structure.
Then you will need to weld the two half meter bars between the two remaining ones (the 1.1 meter ones) to form a rectangle; with the short pieces on the side and the long ones perpendicular. With this step you will shape the back.
Now is the time to work on the sides. Hold the back panel vertically and cut two more pieces of pipe about half a meter long to splice one to each side of the back frame. Also position the front part vertically and fix the two panels with a clamp so that they remain in this position. Next, square the bottom pieces of the side and make sure they are attached.
You will still need two more pieces of bar that will connect the panels at the top. The front part being higher, in this case the bars will be at an angle. Make sure the pieces are exactly the right size to fit together and that they are identical. If so, attach them to the two panels and once everything is square, solder the parts together.
To complete the structure, only the lower part will remain. Lay it with the front part on the ground and insert the 1.1 meter piece you had left in the lower part, about 10 centimeters from the front panel.
Second step: Make the door.
Take the square tube again and cut two pieces of about 1.2 meters and two others of half a meter. Check that the dimension is correct against your front face and, if so, weld the structure. The idea is that the door fits snugly and overlaps the front frame. Next, cut a 1’2×2’5 piece of sheet metal to attach to the structure you just created for your door so that it is covered.
Third step: Create the cover.
Before starting to cover, the ideal is to fix the supports on which the trays will rest later. To do this, cut a dozen pieces of wood half a meter long. On the back, make the marks at the same distance to place five supports. Once you have them, attach the pieces to the sides.
To absorb the heat, cut a 4 foot piece of sheet metal about half a meter and place it on top of the lowest board on the sides and bottom tube of the door. Once adjusted, screw the part.
At this point, it’s time to start covering. To do this, cut the polycarbonate panel in half and attach it to the frame, one part on the upper strip and another on the back. Fix the panel to the structure with the self-tapping screws. To do this, you will need to drill several holes around the perimeter.
To cover both sides and bottom, cut pieces of sheet metal to fit the size. Do not forget to leave a free space of 10 centimeters on the bottom side of the door, to serve as ventilation. With two more pieces of sheet metal, you need to cover the bottom and top of the door, leaving spaces for ventilation. Finally, with two other parts of the tarp, you will prevent insects from sneaking through the ventilation inlets and outlets.
At this point, cut four mold strips, one 1.2 and the other 1.1 meters. Staple the 1’2 to the screen and, using small screws, attach it to the polycarbonate panel at its lower end. The idea is that the screen is suspended from the central part. Make sure that it is held on the sides, also by means of screws.
Now proceed to place the other part, the 1’1, in this case between the upper part of the front panel and towards the center of the sheet, in its upper part. Screw it on and staple the free spaces in the sheet.
Then join the lower screen to the side bars with several screws, so that the screen remains. Also secure the metal pieces at the bottom and around the door opening with screws. Finally, apply silicone to the edges of the panel and the sheet.
The last step before finishing the cover will be to paint its interior black and, above all, the sides and the heat collector.
Fourth step: Activate the food trays.
To have your solar dehydrator ready, there remains an important step: create the trays in which you will place the food. To do this, cut eight pieces of wood about 1.1 meters, and another 12, now a little more than half a meter. Glue and screw the pieces so as to create rectangles which, in addition, must have support in the central part.
Now get four pieces of 1.3×0.7 meter screen. Fold the edges and staple them to the rectangular pieces of wood, if possible so that they are taut.
Finally, add two screws to the bottom of each tray, one on each side. It is important that they are about 2.5 centimeters from the end of the tray and, also, that you do not screw them all the way in, but rather let them protrude a little more than a centimeter. With this, sliding the tray will be much easier.
Step Five: Everything is ready to dehydrate your food.
Before finishing, do not forget to equip the door with hinges and a latch. With this, you will have your home dehydration equipment using solar energy ready. Before you get to work, place it in the sun and wait several days for it to get rid of paint and silicone residue.
With that, everything will be ready to test your equipment. If you want to control the temperature, you can place a thermometer inside. As a guide, it’s ideal to keep it at around 54 degrees Celsius so that fruits and vegetables dehydrate quickly and efficiently.
original project in Instructables.