Building a simple Solar Oven

In our series ‘Identify what you need to put aside‘ we included the components for a simple solar oven in the article on Cooking.

Here are the instructions for constructing that solar oven.

Components

• Cardboard Box approx 20in x 20in
• Cardboard Box 22in x 22in (1in bigger all around than above box)
• Sheet Cardboard (3in bigger all around than bigger box)
• Sheet Cardboard (Same size as smaller box)
• Aluminium foil to completely cover inner box and two outer boxes
• Matt Black paint. (Non toxic) Spray or paint.
• White Glue
• Wire coat hanger
• Old Newspaper
• Sheet Glass (Same size as bigger box)

Assembly

1. Close the bigger box
2. Put the smaller box on top of the bigger, ensuring you leave 1in all around and draw a line on the bigger box around the smaller box
3. Cut out the hole in the bigger box for the smaller box
4. Ensure the smaller box fits in the bigger box leaving a 1in air gap at all sides and the bottom. Cut smaller box if necessary
5. Cover the complete inside of bigger box, including top flaps, with aluminium foil and glue into place
6. Cover the inside of the smaller box, no need for top flaps, with aluminium foil and glue into place
7. Put crumpled newspapers in bigger box to support smaller box so top of smaller box lines level with top of bigger box
8. Glue inner box flaps to top of bigger box
9. Trim inner box flaps to remove excess overlapping bigger box
10. Put larger cardboard sheet on box and mark the edges
11. Cut, fold and glue larger cardboard sheet to make a box lid to fit over bigger box with approx 2in lip
12. Make a flap in the box lid by cutting three sides and leave one side, at the back, as a hinge
13. Carefully break the cardboard to make a smooth hinge. It is best to weaken it with a scalpel to ensure it breaks correctly
14. Line the inside of the box lid, and the flap, with aluminium foil and glue in place
15. Cut coat hanger to approx 12in
16. Bend 1/2in at 90^o at both ends to make an S shaped prop
17. If necessary glue a fold on the outside of the flap to hold the prop
18. Ensure smaller cardboard sheet fits easily in the oven. Trim if necessary (This is a removable tray)
19. Cover smaller cardboard sheet with aluminium foil and glue in place
20. Paint foil on this cardboard sheet black
21. Wait for everything to dry and it is done

Simply place in the sun, put removable tray in oven, this is to protect oven from food and drips and can be replaced as necessary, put pot on tray and cover with glass panel. Adjust flap to reflect sun into box and fix with prop. Wait till food cooked and there you go. It will take about twice as long as an ordinary oven but depends on how the sun is shining. When cooked you can lower the lid and keep the food warm until required. When finished remove the pot and tray and wipe down.

A cast iron pot is better for cooking as it retains the heat better.

Instructions for more sophisticated home made units can be found in Homestead Files as well as at the Solar Oven Wiki. In addition there are now many professionally made solar cookers available on the market.