The Panel Cooker
Box Cooker
REGIONAL TECHNICIANS GROUP
Solar Cookers
One of the sessions conducted at the Lab2000 laboratory staff conference was the construction of solar cookers presented by Dave "Sunny" Miller from the Solar Cooking Interest Group.
Two different styles of cooker were constructed:
|
|
|
The Panel Cooker |
Box Cooker |
The Panel Cooker
In use, the front reflector is raised until the maximum amount of sunlight is directed onto the food to be cooked, which is also covered with a glass jar to produce a "greenhouse" effect.
Detailed construction plans may be found at the following web address:
http://solarcooking.org/newpanel.htm
The cooker made during Lab2000 was constructed as follows:
The two rear reflectors were cut from 2 sides of a cardboard box and the front reflector made from the remaining two sides of the box which, when trimmed, formed a hinged reflector. The base of the side reflectors were glued to the flap of the front reflector using PVA glue and weighted with bricks until set. The surfaces of the reflectors were covered with aluminium foil (shiny side outwards) using PVA glue diluted 50:50 with water.
|
|
|
The Box Cooker
Detailed construction plans may be found at the following web address:
http://solarcooking.org/easylid.htm
The cooker made during Lab2000 consisted of five parts, an inner box and an outer box (with insulation between the two boxes), a black painted cooking plate, a lid with glass panel and the reflectors.
Computer cartons are very good for this type of cooker although any strong 5-ply cardboard carton is suitable. A computer carton was selected for the outer box and a monitor carton for the inner box which fitted with enough space between the two boxes to allow room for insulation (approximately 50mm all around.)
 |
The computer box was cut approximately 250mm high and a 50mm wide lip bent inwards on the top edges. This provides a lip to fix the inner and outer boxes together. To enable the thick cardboard to bend easily it was first "dented" (rather than scored) along the inside of the line of bend, using a simple tool made from a metal eyelet screwed into the end of a piece of broom handle. The bottom flaps of the box were left intact. The inside of the box was covered with aluminium foil by gluing the dull side of the foil to the cardboard using PVA glue diluted 50:50 with water. The 50mm lip was not covered with foil. |
| The inner box was cut from a monitor carton and a similar lip bent outwards at the top. Three strips of card, each approximately 20mm wide, were glued to the outside of the base of the box to elevate it from the outer box when constructed. The outside of this box was covered with aluminium foil (shiny side glued to the cardboard), and the inside of the box covered with the dull side of the foil glued to the cardboard. | 
|
|
The two boxes were fitted together by inserting the inner box through the base of the outer box and the two lips glued together using PVA glue. Before the base of the outer box was glued down, loosely crumpled newspaper was laid between the two boxes and between the ribs of the base to act as insulation. The outer box was then sealed and weighted with bricks to hold the two glues lips together until set. This whole procedure must be completed quickly before the glue sets - many hands are helpful. |
This photograph shows a cross-section of two boxes fitted together with newspaper insulation loosely filling the gap between the two.
| The lid was made from the remaining half of the computer box which was cut to
fit neatly over the lower assembly and form a good seal. By utilising the flaps
on the box, and leaving one side of the lid longer than the other three sides, a
hinge was formed to enable the lid to be tilted back rather than lifted from
the cooker when in use. The extended hinge flap was glued to the side of the
box. A hole was cut in the lid approximately 50mm smaller than the sheet of glass and the glass held in position, on the underside of the lid, with strips of cardboard of the same thickness as the glass glued around to hold the glass in position. Wider strips of thicker cardboard were glued to the thinner card overlapping the sheet of glass to hold it in place. |
|
|
Two reflectors were cut from another box, again utilising the flaps as hinges so that the reflectors can be folded flat for easier transport. Also, with the reflectors folded down, heat may be maintained within the oven for a number of hours after cooking. The reflectors were covered with aluminium foil by gluing the dull side of the foil to the cardboard using 50:50 PVA glue and water. The hinge flaps of the reflectors were glued to the sides of the lid using PVA glue. The reflectors can be held in the vertical position using string threaded through holes or velcro strips and spots. |
Finally, a piece of galvanised metal plate painted with flat black paint (black stove enamel is most suitable) was positioned in the bottom of the inner box, elevated slightly by 25mm square pieces of double thickness cardboard glued together and to the underside if the plate. The cooking plate should cover as much of the bottom of the inner box as possible without touching the sides which might otherwise damage the foil lining.
| The hinged lid (referred to as the "Farby Hinge" after its inventor) provides easy access to the food inside the cooker. | 
|
Points to note:
|
This very innovative idea for a solar box oven was produced by Faye Allanson from Ocean Reef S.H.S. using an old safety glasses cabinet. The inner foil-lined box is insulated from the sides of the cabinet again using loosely crumpled newspaper. Despite its smaller size, this oven will also attain temperatures of up to 135oC |
