The observed atmospheric climate changes and awareness on the limited supply of fossil fuel reserves have accelerated the use of renewable energy sources for decelerating the climate change and ensuring the availability of energy also in the future. The research activities in the solar energy are concentrating on the grid interfacing problematics of photovoltaic generators. A solar power plant of 13 kWp containing 69 pcs of 200-W solar modules organized in three strings is mounted on the roof top of DEEE building for practical testing of different interfacing converters and the effect of changing environmental conditions on their performance. Artificial solar simulator capable of illuminating four afore mentioned panels is under construction by means of which deterministic testing of the effect of varying environmental conditions such as level of irradiation, ambient temperature, and shading on the PV generator properties can be performed. The recent research has revealed that the worldwide understanding of the PV interfacing constraints and the real nature of different interfacing DC/DC and DC/AC converters is quite poor. A paradigm change in the power electronic converters used in the rewable energy applications has taken place without recognition.This is quite worrying because of the strategic role of these energy sources in the future. Many of the basic problems have been solved and the real interfacing constraints are revealed during the research. The recent research efforts are focused on the dynamic behavior of the grid-connected inverters and their effect on grid dynamics. The initial research has revealed that the grid-parallel-connected inverters in renewable-energy applications may have negative-incremental-resistance-like behavior at the low harmonic frequencies in their output impedances explaining the reduced damping in the grid connection and certain instabilites when an output filter is added in the inverter.