Sugar may be caramelized in a pot/pan, or in a box cooker. The usual temperatures in standard cookbooks, etc. are a bit too high; the slow heating of solar cookers means more time is spent at a given temperature, so various stages of caramelization actually happen at lower temperatures than on a conventional stovetop. Roughly, browning (in a box cooker) begins at 285^oF (140^oC) and 300-315^oF (149-157^oC) is hot enough to burn it.