The 1979 photovoltaic Solar Energy Conference was organi zed by the Commission of the European Communities in co - ope ration with the Sen at von Berlin and the Institute for Elect- cal and Electronics Engineers.This conference, as the first one held in Luxembourg in 1977, reflected the interest of the Com mission in solar energy research and development : within the Commission's R&D programme the photovoltaic part takes one of the largest shares. The presentations.and the discussions of the recent advan ces in photovoltaic technology inspire confidence that this tech nology in the long run will provide an alternative energy system. The increasing industrial interest is an indication of the ope ning of the market, which is a condition for a rapid decrease in cost. I hope that the success of this Conference will be an en couragement to all countries to allocate the R&D funds which are necessary to continue the further development of this tech nology. I also hope that this Conference contributed to strengthen the international co - operation.