He then began his own experimentation with various type of solar cookers. Unique to his location in southeast Asia, the sun travels a route that is virtually directly overhead. He developed a design for a solar panel cooker with tall side reflectors than can easily be rotated on a flat reflector base suited for locations near the equator. See: Solar Rice Cooker The tall sides of the cookers allows for the stacking of multiple cooking pots. Importantly, this design also provides space for blackened stones to be placed under the pots. The stones heat up throughout the day and provide more consistent cooking temperatures, and will extend the cooking period into the early evening. He began teaching solar cooking in 2004.