Hello everyone

This instructable is for making a portable panel solar oven. The shape of the oven is a truncated octagonal pyramid which can be flat folded. This makes it easier to store or carry it wherever needed. I have used materials which are usually available at home.

Step 1: Material and Tools

List of materials :

- Aluminum foil

- Mount board (2mm thick)

- Cellotape

- 10 (magnets)

- Mount board

- Marker

- Two concentric glass bowl

- Black paint (I have used acrylic colour)

List of tools :

- Steel ruler

- Paper cutter

- Paint brush

Step 2: Construction of the Oven

The oven is made up of mainly three parts

1) Reflector :

It is made up of 8 panels which come together to form the truncated octagonal pyramid. These panels are connected to each other such that it forms an open loop with live hinges. The live hinge gives it the ability to be collapsed into a flat structure after the cooking.

2) Base support :

It is a flat octagon with side walls which supports the reflector panels.

3) Cooking container :

It consist of two concentric glass bowls( borosilicate glass is recommended as they withstand higher temperature) the smaller bowl is painted with black paint to absorb the heat effectively. The inner bowl can be of thin stainless steel or aluminium as long as it is coated with black color. The gap between the outer and inner bowl acts as the greenhouse that traps the heat.

Refer the above images for the better understanding.

Step 3: Making the Reflector

The reflector is made up of 8 identical parts.

I have attached a pdf of schematic diagram with dimensions. You can print it on A4 size paper to use it as a stencil.

STEPS :

1) Take a print out of the shape on an A4 sheet or draw it according to the dimensions given in the pdf.

2) Use it as a stencil to cut 8 identical pieces out of a mount board of thickness 2mm.

note : Mount board is strong against bending so 2 mm is good enough. You can use some other board but the thickness will depend on its strength.

3) Now unroll the silver foil and use the mount board cut out as a stencil to draw the same shape with a gap of 15mm (refer the first image). Make sure you draw it on the opposite of the glossy side.

4) Carefully cut the shape and wrap the foil along the edge of the panel. Use the cello tape to stick it properly (refer second image)

5) Repeat this with all the remaining panels.

6) Now take 8 magnets and using the cello tape stick them on each panel at a height of 12 mm from the bottom. (refer third image)

NOTE : you can use 4 magnets instead of 8 but then you will have to stick them on alternate panels. More magnets increase the stability of the assembly.

7) Now take two panels and keep them side by side at a distance of 1 to 2mm.

8) Join the two pieces together maintaining the gap between them (refer fourth image). This layer of cello tape will act as a live hinge. Apply an extra layer of cello tape to make the hinge strong. The gap is important for the live hinge to work smoothly.

9) Repeat this step to join all the pieces to form an arc as shown in the fifth image.

10) Now cut two square pieces of dimension 24mm x 23 mm.

11) Using cello tape stick a magnet at the centre of one of the square piece. Now join these two square pieces with the live hinge as we did it the 8 panels.

12) Using cello tape stick this piece at the top of the last panel in the arc.

13) Finally stick another magnet with cello tape on the other end panel of the arc (refer the sixth and seventh image). This will act as a locking mechanism for the whole structure. You can add one more such lock in the middle for extra strength.

reflector.pdf
Download

Step 4: Making the Base

Steps :

1) Take a print or draw it on an A3 sheet as the dimensions of the base are bigger than an A4 paper.

2) Cut the octagon and wrap the aluminium foil in the similar way we did for the reflector panels.

3) Now to make the supporting walls, cut 8 pieces of the shape given in the pdf.

4) Arrange these pieces along the 8 sides of the base as shown in the third image.

5) Keep a gap of 1mm and stick them to the base with cello tape. Add a second layer of cello tape to make it stronger.

6) Now stick all the sides together with cello tape to form a rigid structure as shown the fifth image.

7) Now stick 8 magnets on each side of the support walls from outside with cello tape. You can use the position of magnets in the reflector panels to locate the exact position. (refer the sixth image)

Now your base and the reflector are ready.

base.pdf
Download

Step 5: Cooking Vessels

I have used two Borosil bowl of different sizes such that the smaller on fits inside the bigger but a gap of approximately 15 mm.

Note : Borosilicate glass is recommended as it can withstand higher temperature.

Dimension of outer bowl (1500ml) : dia - 159mm, height - 94mm

Dimension of inner bowl (800ml) : dia -132mm, height- 78mm

here is the link

For the inner bowl you can use any aluminium or stainless steel vessel with a lid.

You need to coat the inner vessel with black colour to absorb the sunlight effectively. Make sure the paint you use is non-toxic as it is going to be very close to the food.

The arrangement of the vessels is shown in the second image. Make sure the lid of the inner vessel is not air tight as pressure might build due to water vapours.