The Fun-Panel solar panel cooker can be built in 1-2 hours from a single cardboard box, aluminum foil, a pot, and an oven bag. This is significant, because traditional solar panel cookers such as the CooKit often require a large sheet of cardboard for construction. The Fun-Panel can also be adjusted more easily for different sun angles. This very powerful cooker is a true breakthough.
Teong Tan's rationale for designing this cooker is the following: The Funnel solar cooker is very efficient in capturing sunlight with its 60° conical reflecting surface. However, it has an unstable shape that makes it difficult to keep the cooker and the pot in position. Also it is not possible to fit a regular size cooking pot into a regular size Funnel cooker because of limited space at the lower end of the cooker. The Fun-Panel retains the very efficient conical reflecting surface of the funner cooker but eliminates its disadvantages.
This is a very good design to build in construction workshops. Please see Fun-Panel Class Handout.
[Note that Teong Tan has recently released an improved design for this cooker. To see the updated design, see Fun-Panel 2 Construction Plans].
- It's easy to figure out how to cut and fold this cooker using the cardboard from half of a single box -- you don't need a big sheet of perfect cardboard. Every US Post Office sells a large cube-shaped box 50 cm x 50 cm x 50 cm (20 in x 20 in x 20 in) for about $6.00 that can be used to make two Fun-Panels.
- All cuts are 90° cuts -- no curves.
- It is easily scaled to the size of cardboard box you have on hand.
- You can cook at all sun angles including low sun angles (morning and evening or high/low latitudes)
Building the Cooker
What You Will Need
The construction materials required for a Fun-Panel cooker are simple and low cost. Teong made his cooker from a used cardboard box that measured about 50 cm (20 in) on all edges. If you use a box with different dimensions, just modify the design to suit your box. One cube-shaped cardboard box has enough material for two Fun-Panel cookers. If only a rectangular-shaped box is available, you can cut the side panel to make it square.
Creating the Panels
- Cut the cube-shaped cardboard box to obtain two large rectangular panels. Each panel is made up of one square face of the box together with one flap.
- Draw all the fold lines at 15° angles (see a simple way to measure 15°.) and cut lines onto the panels following the Modified Fun-Panel Plan.
- Cut along the cut lines, then fold along the fold lines.
- Glue aluminum foil onto the inner side of the two large rectangular cardboard panels. Mix equal amounts of white glue and water. Wheat paste can also be used. For more information see Glue.
Assembling the Panels
- Join the two large rectangular cardboard panels together according to Figure 2, to form the cooker.
Adding small cardboard support
Setting up the Cooker
Low sun angle
For low sun angle cooking, between 35 and 50 degrees, place the cooker down, with the rectangular panel on the floor, as shown in Figure 4. For very low sun angle cooking, below 35 degrees, raise the pot by 5 to 7.5 cm (2 to 3 inches) above the base to better capture the sunlight.
High sun angle
With rising sun angle, between 50 and 70 degrees, flip the cooker around so that the square panel in the middle of the cooker is now horizontal, and place the cooker on top of a small box. (A box 12-15 cm, or 5-6 inches high, is now required.) See Figure 5.
The small box serves to support both the cooker and the cooking pot in this high sun angle setting. For very high sun angle cooking, above 70 degrees, tilt the vertical, rectangular panels slightly backward until the pot receives maximum reflected sunlight. Tie the two ends of the string together to hold the rectangular panel in that position.
The pot and plastic bag
To cook, put foods inside a suitable cooking pot. Enclose the pot in a oven cooking bag. Use an oven cooking bag alone or a normal plastic bag around a wire frame to keep the pot from touching the bag (to avoid melting the bag). Set the cooker according to the sun angle, and face it towards the sun. Place the cooking pot in the cooker and start cooking.
The Fun-Panel cooker is also capable of cooking without the plastic bag enclosure if you have good sunshine. A test in Singapore without the use of a bag recorded a maximum empty pot temperature of 130 °C (266 °F). The 4-liter pot used had a clear glass lid. The cooker was set to the high-sun angle setting, and the sun's angle was 55 degrees when the temperature was taken.
A large rock can be placed on the back shelf to help stop the cooker from blowing away on windy days. If more wind stability is needed, tie a string to each upper corner of the reflector wings (~5 cm, or 2 inches, in from each edge.) Then tie the strings to stakes in the ground or heavy objects such as a rocks, bricks, etc.
Some users have found positioning the reflector can be helped by attaching a string between the upper corners.
In 2009 Celestino Ruivo developed a Fun-Panel in concrete using mirrors for reflecting the sun rays to the pot. To make the green house effect he used two recycled windows of clothes-washing machines instead of a plastic bag. This model is working now during winter time, no problem with rain and wind, it is easy to clean and it is very heavy and thus theft-resistant. The funnel solar cooker in concrete with mirror can be a good alternative to a more durable solar cooker (many years) instead of some months of a solar CooKit. In African countries, this kind of solar cooker may also be constructed locally.
Making the Fun-Panel Collapsible (Optional)
Fun-Panel Version 2
- Teong Tan has recently updated this design. See Construction plans.
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