The demand of photovoltaic (PV) converters with high efficiency and low cost has supported the investigations in new topologies in the last years. Especially transformerless topologies are able to achieve highest efficiency values and lowest specific costs [1]. In order to support these goals as well as to obtain a high power density [2] the functional integration of magnetic components is a known technique. Integrated magnetic components will lead to reduced number of magnetic components and are able to achieve application specific functions [8]. This paper will present the design of a coupled inductor for a new transformerless buck-boost inverter topology for photovoltaic applications. The coupled inductor will serve as energy storage as well as transformer in order to transfer the power to the grid. As basis for the inductor development the inverter topology will be briefly explained. The design procedure including an analysis of the magnetic components is presented as well as simulation and experimental results. (6 pages)