Photovoltaics

Photovoltaic technology has made increasing progress towards cheaper and more efficient modules in recent years. One challenge in the application of solar modules is the degradation of their performance due to environmental influences. Factors such as temperature, irradiation and shading play a decisive role. These influences can significantly affect the performance of the module and thus represent a major problem that must be taken into account in the development of photovoltaic systems. One concept for describing the properties of a PV-module is the VI-characteristic line, it shows the current on the y-axis and the voltage on the x-axis and thus provides information about the behaviour of the module under different environmental influences, irradiation and shading.

VI-Curve of a photovoltaic module

Figure shows the characteristic curve of an ideal PV module. From this it can be seen that the behaviour of current to voltage is not linear and there must be a point on the characteristic curve from which the product of current and voltage is maximum. This point is called the MPP and should be the operating point from which the maximum power is obtained. How to set this operating point is described in the maxium power tranfer chapter of the power adjustment. Furthermore, the current is almost constant over a wide range, which is why the solar cell is also called a current source.