Where does the energy that starts the process of photosynthesis come from
Generally the energy comes from sunlight. But as well proven in scientific circles, any light that mimics sunlight will do.
This is fairly simple and I'm not sure if it's the answer your looking for but....The sun.
The visible light frequencies of the electromagnetic spectrum of the sun.
the energy comes from the sun and is stored by the chlorophyll on the top layer after the waxy green layer