A selectable voltage range is maintained, as a function of the respective cell temperature and the intensity of the global radiation, by optimising the series-connected solar cells. The modules or module rows thus formed are connected in parallel in order to produce the current level. The current level can be adapted as a function of the load by connecting or disconnecting individual modules or module rows. The voltage and the current level are matched in a step-by-step manner. This circuit can be used for small and large installations.
