When light is absorbed by the pigments, the electrons in the pigment molecule become excited and get captured by the electron transport system. This releases energy, with some of this energy being used to generate ATP by the enzyme ATP synthase.
The rest of the energy is used for photolysis of water. Photolysis is the process by which water is split into oxygen, which is released into the atmosphere, and hydrogen.
The hydrogen then becomes bonded to the coenzyme NADP to form NADPH and is transferred to the Calvin Cycle along with ATP.