Question

What is the range of temperature which can be achieved in a box-type solar cooker in two to three hours ?

Answer 1

After two hours in good, clear sunlight you should have a very high temperature in your solar cooker, if you have a well made solar cooker that is well insulated and has reflector panels that concentrate the maximum amount of sun possible into the oven.
The temperature range can be between 150 F (66 c)to 400 F (204 c) if you have a well made solar cooker.