by Carol B
You will be building three (3) different box-like units, all of which will fit together and work to dry your food in the sun.
The finished dimensions of your solar dryer will be two (2) feet by four (4) feet. You will not be building legs from these directions, but could do that very easily “whenever”. If you are going to build legs, we suggest using PVC pipe and setting them in 5-gallon buckets, with enough sand or concrete to hold them in place but allow for water in the bucket.
The water will keep ants and crawly things from crawling up the legs while your food dries. I do not do this; I simply check it from time-to-time and make sure there are no critters; so far, so good.
You can use virtually any wood you like; we used cheap pine because we’re cheap; but, it’s not well finished, and I have managed a couple of splinters in handling the pine, so, consider that when deciding what wood to use.
You can spray paint your metal sheet on one side and let it be drying while you build your boxes (see box # 3, below).
Box # 1 (bottom): you will need 2-inch x 4-inch wood (untreated – you do not want chemical toxins in your food supply) and a 2’x4’ sheet of corrugated metal roofing-type material. The first box will be the bottom box which will hold the sheet metal “heater”. Build your two (2) foot by four (4) foot box – we did not center support this box, but, you can if you want.
Attach a sheet of corrugated steel to the top by whatever means you prefer (nails, bolts, screws), so long as it lies flat against the surface of the frame, and covers the entire frame, two feet wide by four feet long.
You will need food-grade polypropylene screen, and you can order it from the folks below. DO NOT try to use aluminum screening or recycled housing screening for a food project. You will also need screening spline and a sharp instrument for cutting.
We purchased polyethylene screening from www.dryit.com email: email@example.com 1-800-609-2160 MacManiman Inc. 3023 362nd Avenue S.E. Fall City, WA 98024
Box # 2 is not one, but two (2) separate boxes built of 2”x2” boards, each of them two (2) feet x two (2) feet square. Build your frames. Dado the top of them out to create a groove to receive your screening and spine.
Cut your screening to fit across the tops of each of the two boxes, allowing extra to hang beyond frame; place your spline and, using a spline tool, work the splining material into the groove. Trim any excess. Having two separate frames will allow you to dry more than one kind of food at a time, if you wish, without having them “blend”.
For # 3, you’ll need sheet metal (either one 2 ft. by 4 ft. sheet, or qty. two 2 ft. by 2 ft. sheets; black spray paint, and two ft by four ft (2’x4’)’ Lexan or Plexiglass (have it cut at any window glass store) sheet, washers and screws, and waterproof clear acrylic sealant). The Lexan we bought was about $40, so, expect to pay $$$.
Box # 3 is a single 2’x4’ frame which is braced across the center; cut sheet metal to fit 2’x 4’ (we used qty. two 2’x2’ of sheet metal 1/16 inch thick, because, that’s all we could find). Spray paint both sides of the sheet metal; allow it to dry.
Use screws or nails to attach sheet metal to one side of 2’x4’ frame; this will become the bottom of this piece. Lay a bead of silicone for the Lexan, all around. Now attach the Lexan across the top; you can pre-drill it and attach with screws. Allow to dry.
We have old lawn chairs that we use as “legs”. It is important that the solar dryer be slightly angled for natural air circulation and turned toward the sun (duh!). We get a lot of sun in the Deep South, so solar drying is a natural choice.
This unit does not utilize any kind of fan, or anything requiring power; you could run a fan under it, and, for some types of foods, it might help them dry faster. Most foods don’t require anything, other than checking from time-to-time until you learn how long that food takes to dry where you live.
Some foods, however, may do better if you turn the foods (move them around) every few hours – although I’ve used mine extensively and rarely turn the food.
Tip: All foods dry better if they are uniform in size; otherwise, smaller pieces will be overly dried while you wait on the larger pieces, or, you’ll have to pick the smaller pieces out in advance of the others, which makes this much more labor intensive – not necessary!
To use, the sheet metal box is the bottom; place food on drying screens (don’t pack it too tight) and place drying screens atop sheet metal heater box. Now place Lexan cover box on top, with black painted metal as the bottom of this box and Lexan facing the sun. Start cooking!
I hope you enjoy your homemade solar dryer; keep it out of the elements when not in use, and you should get years of service from it.