Photovoltaic Solar Energy Conference, Lissabon 1991 Solarinverter for grid-connected PV-systems (Prof. Valentin Crastan Dr.Ing., Ingenieurschule Biel) Abstract  of the report In Switzerland there is a need for small grid-connected PV-plants in the range 3 to 20 kW. At the Ingenieurschule Biel (ISB) concepts for small grid-connected inverters have been studied. the principle utilized excited the interest of industry, and so  the SOLCON-project, for the development of the first commercial Swiss grid-connected solar inverter was started. It was  carried out together with Alpha Real, Zürich and Concept Technology, Biel and sponsored by the Federal Office of Energy. At the time ISB is developping a three phase inverter SOLARMAXimizer for 20 to 35 kW. Principle and first results are presented.