The main factor that drives photosynthesis in plants is solar energy, specifically sunlight. During this process, plants convert light energy into chemical energy, producing glucose and oxygen from carbon dioxide and water. Chlorophyll, the green pigment in plant cells, absorbs sunlight, and this energy facilitates the transformation of lower-energy compounds into higher-energy sugars. This foundational process not only sustains the plant itself but also supports the entire food web, as it is the primary source of energy for most living organisms.