In this chapter, a model that calculates the impact on the grid of the simultaneous injection of electricity both from photovoltaic and wind sources is presented. The best locations for wind and photovoltaic technologies within Región de Murcia, southeast Spain, have been selected from a GIS database and evaluated and classified using a fuzzy version of the multicriteria decision method called Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). After the classification, the best locations are selected for each technology. Then, the impact on the grid arising from the injection of power generated in wind of photovoltaic systems installed at these specific locations and that are connected to the grid has been calculated in a power range of several kWp, including random steps of up to 50kW. The results show that stable grid parameters are obtained within 500ms in all cases, even when this relatively large power surge (or variation) is considered.