Short wavelength solar radiation passes through the glazing, and strikes the interior sides of the oven and the cooking pot. The interior sides of the oven can be either reflective or black. If reflective, the sunlight reflects onto the pot and heats it. If the sides are black, the sunlight is absorbed and then re-radiated at longer wavelengths, heating the oven interior and cooking the food. The glazing also helps to keep the heat in the box.
Solar ovens use both direct and indirect solar radiation.
This allows them to operate better than concentrator cookers under slightly cloudy conditions. Also, because of their shape and weight, wind does not affect their performance as much. They also retain heat longer. Placing an insulated cover over the aperture glazing helps to reduce heat loss and keep food hot if thick clouds block the sun for extended periods. Solar ovens only require repositioning to face the sun every 30 minutes to an hour to maintain an adequate cooking temperature.