Wireless sensor systems are often supplied by solar cells. Solar power is one of the most predictable sources in energy harvesting and, therefore, it is often preferred. The optimal use of the incoming energy is substantial, therefore, the usage of the cells has to be improved by impedance matching andmaximumpower point tracking. This contribution gives an overview on the determination of the incoming power and typicalmethods to improve the utilization of the cells. As today a huge number of maximumpower point trackingmethods exist, which differ just in very small aspects, the main and most important methods are described here.