The Panel-Box Cooker is a working prototype solar cooker, designed by Paul Hedrick, living in Seattle, Washington. The catalyst for this design approach came from Pat McArdle's request to advance design possibilities for an inexpensive durable solar cooker, that can be disassembled and stored flat. The request also included finding an alternative to using the typical turkey roasting bag for a cooking enclosure. While the the turkey bags are inexpensive, and can in theory be used many times, they can be soiled when pots are removed from the bags and hot food happens to spill in the bag. The bags must be discarded, as the cookers are often used in areas where available water is quite precious, and the bags cannot be rinsed out.
The Panel-Box Cooker combines the technologies of both a solar panel cooker and a solar box cooker. The cooking enclosure assembles to become a rigid box, and uses part of panel reflectors to provide the back and the bottom of the enclosure. The reflector panels are fabricated from plastic flute board, which hinge together using plastic zip-ties, and are covered with reflective material. The bottom, sides and front panels hinge together as one piece, and the two-piece rear reflector as another. Both can be folded flat without disassembly. The rear reflector uses a notched slot to connect to each of the cooker sides. Once the panels are in place, four rigid pieces of twin-wall polycarbonate notch into the reflector panels forming the cooking enclosure. The assembled enclosure is 25 cm(10") x 25 cm(10") x 18 cm(7") high, once narrow cross pieces of polycarbonate are fitted into the bottom of the enclosure to raise the cook pot off the cooker base.
The twin-wall polycarbonate material is usually used for greenhouse glazing and is UV protected, and provides some insulation for the cooking chamber. And though the cooking enclosure is not a totally sealed box, it has proved to cook as well as the turkey bags. Because it can be dissembled, it can be easily wiped clean for reuse.
Fabrication of the cooker requires only a utility razor knife, hole punch, and pliers. Cutting the polycarbonate material with a utility knife requires a steady hand. There have been some wrinkling problems with laminating tinfoil to the flute board. The flute board expands some from ambient heat sources, and when it cools it will wrinkle the tinfoil a little. While it doesn't look so great, it does not appear to affect performance. Applied 10 cm(4") metal tape strips appear to adhere better than tinfoil applied with spray glue. Also the black color of the flute board probably also does not help with material expansion, but it was the only color easily at hand when work began.
The side reflectors stay in a fixed position, while the front and rear reflectors can be raised to create a solar bowl when the sun is overhead, and tipped forward when the sun is low. The rear reflector redirects considerable light in this position, and lowering the front reflector avoids shadowing the cooking enclosure, as well as redirecting light. The adjustable reflectors hold their position using office stationary clips. Behind the rear reflector there is a shelf area to place rocks, to stabilize the cooker in windy conditions. Adjustable reflectors are an important feature to include in a cooker designed to stay flat on the ground.
When disassembled and folded flat, the cooker fits into a 76 cm(30") x 46 cm(18") x 5 cm(2") space. Fabricating the reflectors requires a 122 cm(48") x 122 cm(48") piece of flute board.
Audio and video
- See Paul Hedrick.