The main PV system aspect is grid integration, taking into account the intermittency of the solar source, far beyond the alternation of day and night. Consider for instance the case of Ecole Polytechnique campus in summer, two consecutive days. We present direct irradiance in blue. On red, diffuse irradiance. The green curve shows irradiance on a horizontal plane. The first day is very sunny, except perhaps in the evening. The diffuse irradiance is less than 10% as compared to the direct one. The next day, on the contrary, is characterized by intense on sudden clouds. Sometimes the scattered irradiance can approach 500 watt per meter square. The direct irradiance becoming negligible. With present years, always in summer, electricity demand in France, compared with the integrated production of PV on wind. The alternation of day or night characterizes both the overall power demand on production of PV in the same way. Note that the seasonal variations of particular storm at higher latitudes. PV on wind power appears quite complimentary. The wind is more intense in winter, and shows no alternation of day and night. There are solutions to manage the integration in grids such as improved weather forecasting, storage, or use of information technologies, the so-called, smart grids. This grid integration problems increases with the penetration of PV. Here I present the demand of fossil fuels of spring there in California. This is a famous, duck curve. The demand for fossil fuels during the day has been declining with the penetration of PV, which meets all the needs around noon or approximately. In contrast, late afternoon, it was to face a strong ramp due to the double impact of PV production decline on increased demand. Conventional power plants mostly gas, must be in operation at that time. Solution of storage on smart grid must be implemented to deal with this ramp. A geographical integration helps, averaging the effect of intermittency as shown in this figure is a case of wind power. The wind farm is North of Brittany in France, is very sensitive to rapid situations of the wind. These variations are less sensitive at the regional level, Brittany, red curve, And especially, national, blue curve. However, wind energy shows strong fluctuations from one year to another as shown here. Up to 30% in winter. Such variation can affect the whole of Europe. PV is less affected by the changes as shown here. However, a regional or national aggregation allows to average typical effects such as intermittent rain. The winter contribution of PV in Europe is weak. Recent average load factor of 5%. This factor is multiplied by four, in average during summer. In general, a penetration of renewable requires changes in depths of the electricity distribution processes. Currently, the distribution of electricity is based on the fit and forget method, only with centralized control. This method is not applicable to the presence of meetable production centers such as PV. The frequency on voltage controls must be implemented to ensure the quality of the grid. It is the same for safety system islanding, which should take into account the decentralized PV production. Penetration of PV must be correlated with the implementation of new interconnection regulation processes as shown in this figure. We will continue in the following seconds on the same system aspects, with a short review of the values electricity storage techniques. Thank you.