Continuing from my previous post on the topic, I had tried out different vessels (glass, steel, ceramic and plastic bag) in the experiment. But none were black as the inner box itself had black paper walls. It turned out that the rice in the plastic bag seemed to be the best cooked among the four. However the sizes and shapes of the four containers were not the same to make an apple to apple comparison. Further the initial water to rice ratio (2:1) was insufficient and water had to be added in between. In any case using plastic bags daily was not an option. The cooking was continued on day 2 with only a steel vessel. The results showed that the rice was not uniformly cooked (there were grains of raw rice) while portions seemed well cooked. I am yet to get clarifications from the veterans of solar cooking on this aspect. Will post an update when I receive it.
Another operational challenge faced was strong winds blew off the reflector portion of the solar cooker. This could be temporarily solved by sticking it to the lower half with tape. The tape needs to be removed every time the lid is to be opened and hence is not a proper fix. Need to solve this problem too. Further the reflector is a bit fragile and so even if the wind does not dislodge it the shape gets distorted. Again a temporary fix of placing cross rods inside was adopted.