We’ve been baking up a storm at the Space Place this week with our home-made solar ovens. Solar ovens come in all shapes and sizes, but ours are made out of cardboard boxes, aluminium foil, and plastic wrap. All things most people already have lying around the house, making them highly affordable for everyone.
In places where electricity is not readily available people use solar ovens for most their cooking. In one Kenyan village a group of woman have even started their own bakery, making cakes and cupcakes to sell. On a good day they can bake over 100 cupcakes in their solar oven! Here in New Zealand solar cookers can be useful in the event of a natural disaster or if the power goes out for a long period of time. They can also be quite convenient when it’s hot outside and you don’t feel like turning on the oven!
There are many factors that influence how well a solar oven cooks. As we learned on the very first day of class, solar ovens aren’t nearly as useful on rainy days! Cooking time is also doubled when compared to using a conventional oven. Our solar ovens only got up to 50° C, but we put them out after noon so we missed the sun when it was at it’s highest point in the sky. Solar ovens never get as hot as conventional ovens, instead they cook over a long period of time at moderate temperatures.
When using a solar oven it’s best to start early in the day so you are cooking when the sun is highest in the sky. During New Zealand summer 9am – 2pm is prime cooking time. Adjust the reflector flap so it is directing sunlight down into your oven window. You may need to move your oven periodically as the sun moves across the sky. Cupcakes will take at least two hours to bake on a sunny day.
Remember to always place your food in a black cooking vessel. If you don’t have a black cooking vessel, wrap black paper around the cooking vessel you do have. Black absorbs heat, whereas lighter colours, such as white, reflect it. This heat absorption will help your cupcake cook! For added heat retention, place your cupcake inside an oven bag.
Make sure your oven window is shut completely. You can add some masking tape around the edges to ensure no heat escapes during cooking.
Students were sent home with recipe sheets filled with more goodies to try in their own solar cookers.
Try experimenting with your box design.
- Will it work better with one reflector flap, or four?
- What would happen if you covered the entire inside of your oven with black paper instead of aluminium foil?
- What other types of reflective surface could you use instead of aluminium foil?
If you have an awesome solar oven design, idea, or tip let us know in the comments!