First we tried to bake the chapaties with a 2m² Scheffler reflector. Under the indian conditions ( winter, when  the cooker has its minimum aperture and at 600 W/m² direct insolation ) the power was not sufficient to heat the iron  plate ( tawa ) of  230 mm diameter to the reqired temperature of  approximately 300 C°.  The chapaties took too long to get ready ( more than 2 to 3 minutes ) and became dry.

So the area of the reflector was inceased to 2,7 m². The reflector was built at the Barefoot College in tilonia, rajastan, india, together with a women group who took a 2 year long training ( 2004 to 2006 ) on the construction of the 2.7m² scheffler-reflectors.

With this model  the women now cook regulary their chapaties. One chapati typically takes 2 minutes to be ready. They also can bake a thicker type of chapati made from millet, for which the iron tawa is replaced with one made from clay. Initially the heat was unevenly distributed on the plate, burning one half of the chapati while the other half remained raw. This was overcome by adding an additional reflective element directly under the tawa to redistribute the concentrated light.