No other form of energy is so environmentally-friendly, so profitable, and can be used in so many different ways as photovoltaics – the direct conversion of solar power into electrical current. More than two million households in Germany already use the sun as a free source of energy.

Whether it's on industrial flat roofs, private pitched roofs, to provide shade or as a part of the building envelope: photovoltaic systems can be used in a myriad of different ways. They are increasingly considered as an important element of building architecture. Facade technologies along with integrated roof structures with transparent glass-glass modules are giving birth to a whole new range of possibilities.

The term photovoltaics is made up of the word photon (Greek for light), and the name Alessandro Volta, the person hailed as a pioneer in the field of electrical engineering. Sun was already used as source of energy as far back as antiquity. Today, all sizes of solar cells are used all over the world to generate electricity.

Solar cells are thin square silicon discs varying in size between 10 and 15 square centimeters. They are combined to make modules, and the contact bands attached on the front and rear generate electrical current from light energy, also referred to as direct current.

The solar energy is converted through the interaction between the irradiating sunlight and the solar cell's doped semiconductor material. This takes place in a very simple process, with no noise, or exhaust gases. The generated direct current is then adjusted to the alternating grid current using inverters. The electricity can then be fed into the public grid or consumed directly in a building.