Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms' activities.
Synthesis of each molecule of glucose in photosynthesis involves 18 ATP
6 CO2 + 18 ATP + 12 NADPH = C6H12O6 + 18 (ADP + Pi) + 12 NADP+