Manufactured solar cookers can cost in the hundreds of dollars, but you can build one yourself and adjust it to suit your needs for around $75 (or less). Designed with the urban farmer in mind, the “Uniquely Urquhart” solar oven uses minimal power tools and can be constructed in an apartment or on a patio or balcony.
Several additions to the oven are optional, and if you’re thrifty with recycled materials, consider using cardboard boxes instead of plywood for a lighter model. Once you get the hang of cooking with the sun, you may never want to go back to conventional ovens!
What You’ll Need:
- 3 pieces of plywood, 15/16x24x24 inches each
- 1 roll of Mylar or reflective foil insulation, 24-inch x 25-foot (such as Relfectix brand)
- 1 piece of glass, 24×27 inches (a home-improvement store can cut glass to size for you)
- 4 4-inch heavy strap hinges
- 24 bolts with nuts, 1/4-inch-20×1/2-inch
- 12 flat washers, 1/4-inch
- 28 wood screws, 6×1 inches
- 1 cardboard “moving” box, 18x18x24 inches
- nontoxic multipurpose glue, 2-ounce bottle
- optional: Two 12×12-inch and two 10×10-inch slate or unglazed ceramic tiles to hold and regulate heat
- optional: 1 can of black, nontoxic spray paint, such as grill paint, to make bottom of oven more heat-efficient
Tools needed include:
- box cutter
- power drill
- tape measure
Follow these step-by-step instructions to build your oven box.
Step 1: Cut two of your 24×24-inch pieces of plywood into four pieces, as described in diagram A: front, back and two sides. Sand any uneven or rough edges with sandpaper. The third piece of plywood will serve as the base. (Click on diagram A for a larger view.)
Step 2: Using your plywood pieces as templates, cut matching pieces of reflective insulation for each section.
Step 3: Assemble plywood front, back, sides and base to form oven box. The front and back pieces should rest on top of the base, and the sides should rest on the edges of the base so the front and back are slightly higher than the sides. (This will help hold your glass in place.)
Step 4: Use a power drill to predrill holes through the sides, front and back into the base of the oven. Predrilling will help prevent splitting.
Step 5: Attach the sides, front and back to the base of the oven with wood screws to form the oven box. The basic oven box is now assembled.
Step 6: Glue cut pieces of reflective insulation to the inside of the oven box.
Step 7 (Optional): Lay slate tiles on oven base. Paint tiles black.
Follow these step-by-step instructions to construct your adjustable reflector panels.
Step 1: Using a box cutter, cut down the seams of the cardboard box to create four 36-inch-long pieces. Trim 6 inches off two pieces to make four matching 18×36-inch cardboard panels.
Step 2: Using one panel as a template, cut four 18×36-inch sections of reflective insulation. Glue reflective insulation to cardboard panels.
Step 3: Cut 6×11-inch tabs into the front and back panels and 9×1/2-inch slots into the two side panels (see diagram B). For the back panel, tabs should be in the middle (4 1/2 inches from each edge) and for the front panel, tabs should be on the bottom (9 inches from the edge). For the sides, the top slot should be at approximately 45 degrees from the outer edge; the bottom slot approximately 20 degrees from the outer edge. (Click on the image to see a larger version of diagram B.)
Step 4: One at a time, arrange one 4-inch, heavy strap hinge centrally on the top of front, back and side sections of the oven box (plywood), then use a pencil to mark through the holes in the hinge as a guide for drilling. Note: Be sure to leave enough clearance so there is no contact between the hinges and glass top.
Step 5: Predrill holes into plywood front, back and sides, not puncturing the inner layer of the oven box insulation, if possible. Attach hinges with 1/4-inch-20×1/2-inch bolts.
Step 6: Hold each reflective panel above the installed hinge (one at a time), and make guide marks with a pencil through the holes in the hinge. Leave enough clearance so reflective panel can swing freely.
Step 7: Predrill holes through reflector panels, including insulation.
Step 8: For ease of assembly, remove hinges from oven box and attach one hinge to each reflector panel (or have someone help you while panel is attached to box). To attach, place a washer between the hinge and the back of the panel, then run a bolt through the hinge, washer and panel. Tightly secure the bolt with a nut in the front of the panel.
Step 9: Attach all four panels to box. Fit panels into one another with tabs and slots, and adjust reflectors as needed (depending on your location, time of year and available sun).
Step 10: Place cookware in the oven, fit glass in place, nesting it inside the raised front and back panels. Now you’re ready to cook!