Extreme high efficiency PV-power converters

Photovoltaic (PV) inverters convert the DC current of solar generators into AC current and feed it into the grid. There are three basic inverter topologies: inverters with low frequency (50/60 Hz) transformer (LF), inverters with high frequency transformer (HF) and transformer-less inverters (TL). The European market is dominated by transformer-less types (80%), in Japan approx. 50% of the inverters are transformer-less and in USA up to now mostly transformer based inverters are used due to national standards. The efficiency of the transformer-less inverters is up to 98% in series products and in research 99% efficiency has been reached. Such extreme high efficiencies can be achieved with three level or multilevel inverter topologies and new power semiconductors like Silicon Carbide (SiC) and Gallium Nitride (GaN).