A solar oven collects and traps the sun's energy and converts it into heat energy, which is then used to cook food. The success of a solar oven depends on the materials from which it is made. Some materials absorb the sun's energy better, while others reflect it. Picture this: you are standing barefoot on a black road on a hot summer day. What do your feet feel? They likely feel very, very warm! In contrast, if you were to then move to the lighter colored sidewalk, you would not feel as much heat. That is because the dark road surface has a lower albedo and absorbs more of the sun's energy, which you feel as heat. Other materials, such as mirrors, are really good at reflecting some of the sun's energy. In this scenario, the energy from the sun does not get absorbed, and therefore it is not changed into heat energy.

The same principles are at work in a solar oven design - you want dark materials to absorb energy and create heat, but you also want reflective materials to direct the sun's energy. There are three things that can happen to the sun's energy when it strikes a surface: it can be absorbed by the material, transmitted through the material, and/or reflected off the material.

In the interactive lesson on the next page, explore different solar oven designs. Explore the types of materials from which each oven is made, and learn which designs are most successful. Think about whether the materials would be best at absorbing, transmitting, or reflecting the sun's energy.

There will be an assignment associated with this interactive lesson, so please be sure to record your observations about the different solar oven designs. The assignment will ask you to describe and rank the ability of different materials to transmit, reflect, or absorb solar energy. It will also ask you to discuss which materials you would chose if you were to build a solar oven and why.


Source: Solar Cooking. PBS. Retrieved from http://www.pspb.org/e21/media/Solar_Cooking_v105_TN.pdf on November 9, 2010.