1. Photovoltaic Solar Energy: Market and Challenges

1.1 The Principle of Photovoltaic Electricity

Photovoltaics is the direct conversion of light into electricity using a material, typically a doped semiconductor. The energy of the photons is partially transferred to the electrons in the semiconductor’s atoms, causing them to become mobile. The electrons are then separated by an electric field, created by the doping of the semiconductor, to prevent them from recombining with the “holes” left behind after their departure. The electrons thus accumulate toward the anode of the material and the “holes” toward the cathode, thereby creating a photovoltage. In order for the electrons to reach the holes, they must pass through an external circuit, creating a photocurrent. The power generated by the photovoltaic device is the product of the...