We built our “Parvati” solar cooker with plans designed by Shobha Ravindra Pardeshi that can be found here. Pardeshi, who runs an “appropriate technology” company with her husband in India has another design for a similar dish-shaped cooker here. We found both of these cookers (and many more) via the amazing Solar Cooking Archive.
For the Parvati cooker, we cut the cardboard according to the plans, and affixed the aluminum foil with spray glue. For our first pot of rice we used a black enamel pot to better absorb the heat of the sun’s rays, and wrapped it in a roasting bag to increase the efficiency of the cooker. A five gallon bucket made a convenient stand and did not have to be rotated in the two hours it took to cook the rice. Longer cooking times would require re-aiming the cooker as the sun moves across the sky. Temperature in the pot quickly went over 180º F, the point at which food begins to cook. The two hour cooking time is much longer than it would take on a conventional stove, but with a solar cooker there is no danger of burning, making the process, in our opinion, easier than stove-top cooking. Consider a solar cooker a kind of low-powered crock pot for lazy and cheap people–good for things like rice, beans, soups and stews, but not good for sauteing. Just remember the oven mitts–this thing gets hot!
When the sun gets higher in the sky, as we move into summer, this cooker will reach even higher temperatures. We don’t remember where we read this but some folks say that panel cookers like this one cook best when your shadow is shorter than you are which, here in Los Angeles, is right about now. We tried this cooker back in January and it performed well, but did not get above 140º F, which is not hot enough to cook.
Perhaps here around the Root Simple compound we’ll get around to turning our Parvati Solar Cooker into a low rent attraction. Just add some ostriches and we’ll repeat this early 20th century tourist trap in nearby Pasadena (click to biggify):