How to Build a Briefcase Solar Cooker

Though sun-powered ovens are certainly nothing new, Dennis Burkholder's briefcase solar cooker is unusually convenient to carry and use.

| July/August 1985

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    Dennis Burkholder's compact model (it's about the size of a briefcase) is unusually convenient to carry and use.
    By the MOTHER EARTH NEWS Editors
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    Diagram: The Burkholder briefcase solar cooker.

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You can let the sun heat your noontime meal using a briefcase solar cooker . . . while you go about your work or play. (See the briefcase solar cooker diagram in the image gallery.)

How to Build a Briefcase Solar Cooker

Brown bagging it at lunchtime is a great way to save your pennies . . . but the monotony of eating the same old salami every midday can eventually take its toll on your taste buds. If you'd like to broaden your menu, yet still relish the flavor—and price—of a variety of home-prepared lunches, this inch vest-pocket inch solar cooker might be the perfect solution!

Though sun-powered ovens are certainly nothing new, Dennis Burkholder's compact model (it's about the size of a briefcase) is unusually convenient to carry and use. It's large enough to heat four sandwiches, a pair of TV dinners, or a shallow casserole, but small enough to be built quickly and inexpensively, without concern over insulation or fancy reflective surfaces. Furthermore, it's also a lunch box, since the handle and latch fasteners make it portable.

If you study the photo and illustration, you'll see that the briefcase cooker is simply a container with an adjustable hinged lid that incorporates a mirrored inner surface. When that reflective panel is angled correctly, the sun's rays bounce off it and are directed onto a square sheet of single-strength glass set into a groove at the upper edge of the box. Just below that glazing, a second mirror—this one reversed so its black rear surface is exposed—is similarly mounted to act as an absorber. Finally, a third reflector is fixed, shiny side up, about 1-1/2 inch below the absorber plate and is protected on its lower face by a sheet of 1/4 inch hardboard, which serves as the bottom of the box. The front side of the frame is hinged, latched, and sealed with felt to provide a handy access door.

To make your own portable solar oven, you'll need a strip of 1 by 4 no less than 49 inches long, two pieces of 1/4 inch hardboard measuring 12-3/4 inches by 13-1/4 inches, three 12 inch by 12 inch mirrored wall tiles, a sheet of glass with the same dimensions, a 1 inch by 12 inch continuous hinge, a 1-11/16 inch by 2-1/2 inch butt hinge, a 1-1/2 inch by 2-3/4 inch draw pull catch, a 5/8 inch by 5 inch friction lid support, a 5 inch drawer pull, four No. 8 by 1-1/4 inch flathead wood screws, about two dozen 18 gauge wire brads, and a 3 inch by 12-1/2 inch piece of felt.

Start by ripping a 1/2 inch strip off one edge of your 1 by 4 with a table saw, then cut a 1/8 inch by 3/8 inch dado into the 1/2 inch face of that piece. Trim a 36-1/4 inch section from the 3 inch -wide leftover board, and cut three more equally sized grooves into it, spacing them so the end kerfs are 1/4 inch from the edges and the middle channel is 1-1/2 inches from one of those. (If you're partial to casseroles, hoagies, or deep-dish meals, you can increase this distance to 2 inches.)


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