The present dissertation is the result of my individual research activity. It includes experimental laboratory evaluation of multifunction high frequency pure sine wave DC toAC inverter in standalone and grid connected mode, all the development of myexperimental activity has been carried out at the Department of Electrical Engineering andInformation Technology at Ulm University of Applied Science, Ulm Germany. The first step of my work was the configuration of the inverters test circuits, at thePower Electronic Lab of Electrical Engineering and Information Technology Department. The first part of the experiment concerns the measurement of the Phocos Inverter EP1800 Series (Model EP18-4K, 3.2 KW) efficiency in stand-alone mode. The inverter wasconnected firstly at its output terminals with a resistive load, the inverter's efficiency ismeasured at three input voltages equal to the manufacture's minimum, nominal andmaximum DC rated input voltage respectively. At the same input voltages, total harmonicdistortion (THD) of current is also measured. Furthermore measurements have been carried out for many different power levels of the resistive output load to record current harmonicdistortion up to 13 orders, while in order to produce the necessary different input voltagesof the inverter, we used DC variable power supply.