How to Make a Solar Dryer

Solar-powered food for year-round enjoyment.

A solar dryer is one of the easiest solar appliances to build and one of the most useful. While you can dry clothing and linens in your solar dryer, gardeners and hunters prefer to utilize the appliance for preserving nature's bounty for year-round food storage. You can make an efficient solar clothing dryer by tying a clothesline between two trees; an efficient solar food dryer takes more time but is well worth the effort.

Things You'll Need

• 2-by-6-inch lumber
• Measuring tape
• Pencil
• Carpenter's square
• Circular or hand saw
• Hammer
• Nails
• Recycled window in its frame
• Two metal strap hinges
• 1-1/2-inch wood screws
• Screwdriver
• Black fabric
• Wood glue
• Staple gun
• 2 6-inch lengths of 1-by-1-inch wood
• Recycled, framed window screen
• Corrugated sheet metal
• Saw with metal-cutting blade
• Duct tape
• Wood blocks

Instructions

1. Build a box as a base for your solar dryer. The box should be of the same dimensions as your recycled window. Measure and cut four pieces of 2-by-6-inch lumber; two sides will be the length of the window, while the remaining sides will be the width of the window less the thickness of the two length pieces--about 1.5 inch each. If the width of the window is 48 inches, subtract three inches from each width piece to cut. Mark the lumber at the cutting lines using your carpenter's square. Saw with a hand or circular saw along the cutting lines. Assemble the frame by lapping the two length sections over the two width pieces at the corners and nail securely.

2. 

   A used window provides the glazing for your solar dryer.

   Attach the recycled window to the box you have built, using hinges. The window should fit directly on top of the box, with edges even. Apply the hinges to one long edge of the box and then over the window frame, checking to make sure the placement allows you to open and close the window box top freely. Line the inside surface of the window with a piece of black fabric cut to fit; glue or staple it to the wood window frame along all edges. Inside the box frame, screw a 6-inch length of one-by-one lumber at the center line of each short box side, parallel to the top edge of the frame, using a wood screw positioned an inch from the end of each one-by-one piece. These should be loose enough to pivot upright, perpendicular to the frame, to act as props to hold the window top open when you are adding and removing food trays.

3. Clean your recycled window screen thoroughly with dish soap and water. The screen must be slightly smaller than the inside dimensions of your solar drying box so that it fits inside easily.

   If your screen is galvanized metal or has rust spots, cover it with a food-safe porous fabric layer such as garden netting before use.

4. Cut a piece of corrugated metal two to four inches larger than the outside dimensions of your box, using a hand saw or reciprocating power saw with a metal-cutting blade. Carefully seal sharp edges with duct tape. Place the piece of metal on a picnic table top or other elevated surface. Position your solar drying unit on the metal. Raise the entire assembly at the hinged side at a slight angle--15 degrees or so--toward the south for optimum sun exposure, prop beneath metal with wood blocks.

5. 

   Go wild with drying whatever foods you wish.

   To dry food, spread prepared items in a single layer on the screen, place it inside the drying box directly on the corrugated metal surface, and close the window lid. Air will flow through the corrugated spaces to aid drying, and solar heat will be absorbed through the window. The black fabric will aid heat retention, preserve the food's nutritional value and keep the sun from bleaching the color from your dried products.

Tips & Warnings

• Reposition your solar dryer as the sun moves across the sky to optimize solar collection.

• Strip any paint from your recycled window prior to use to eliminate the risk of lead paint exposure.

References

• GeoPathfinder
• Mother Earth News
• Solar Cooking