The development of new technologies for energy implies mastering the process of conversion between the different forms (solar, thermal, chemical, electrical, mechanical, etc.), as well as storage processes:
Solar energy can be directly transformed into electrical energy via the photovoltaic process and stored in accumulators. It can also be transformed directly into chemical energy (hydrogen) by photocatalysis. Electrical energy of every origin, can also be stored in the form of hydrogen, which can be used in fuel cells. The conversion efficiency is directly related to that of the associated electrochemical process (during electrolysis or use in a cell).