Due to the fact that solar and wind energy are intermittent and unpredictable, greater penetration of their types into existing power systems, especially weak grids or island systems without adequate and sufficient storage capacity, could cause and create high technical problems . By integrating the two renewable resources in an optimal combination, the effects of the different nature of solar and wind resources can be partially offset and the overall system becomes more reliable and economical to use. This article discusses grid quality problems with grid connected renewable energy sources and grid quality problems are harmonics and voltage and frequency fluctuations as well as a description of grid connected PV generation system in this article
