Renewable energy use is growing at a much faster pace than the rest of the economy in Europe and world-wide. This and the dramatic oil price increases since 2005 have lead to a remarkable re-evaluation of the renewable energy sector by politics and financing institutions. Despite the fact that there are still discrepancies between the European Union and the USA how to deal with climate change, renewable energies will play an important role for the implementation of the Kyoto Protocol and the world wide introduction of tradable Green Certificates. Apart from the electricity sector, renewable energy sources for the generation of heat and the use of environmental friendly bio-fuels for the transport sector will become more and more important in the future. Photovoltaics is one of the fastest growing industries at present. In the last ten years, the production of photovoltaic cells has increased exponentionally by more than 50% per year, driven not only by the progress in materials and processing technology, but by market introduction programmes in many countries around the world. This growth is realised mainly by an increase of manufacturing capacities based on the technology of crystalline, single junction devices, but thin film technologies could increase their market share over the last five years to about 20%. Consistent with the time needed for any major change in the energy infrastructure, another 20 to 30 years of sustained and aggressive growth will be required for photovoltaics to substitute a significant share of the conventional energy sources. Despite the fact that globally the share of electricity from photovltaic systems is still small, the share of PV electricity at local level can already now be above 30% of the demand at certain times of the year. Future research in PV has to provide intelligent solutions not only on the cell, but also on the module and the system level in order to permit the future rapid growth of photovoltaics in order to become one of the major electricity sources in 2020.