In this paper, the impact of not controllable renewable energy generators (wind turbines or solar photovoltaic panels) on the thermo-economic optimum performance of poly-generation smart grids is investigated using an original time dependent hierarchical approach. The grid used for the analysis is the one installed at the University of Genoa for research activities. It is based on different prime movers: (i) 100 kWe micro gas turbine, (ii) 20 kWe internal combustion engine powered by gases to produce both electrical and thermal (hot water) energy and (iii) a 100 kWth adsorption chiller to produce cooling (cold water) energy. The grid includes thermal storage tanks to manage the thermal demand load during the year and appropriate systems to model any kind of thermal and electrical load profiles. The system is also equipped with two renewable non-controllable generators: a small size wind turbine and photovoltaic solar panels. The system optimization (size and management) including the renewable generators has been carried out using a time-dependent thermo-economic hierarchical approach developed by the authors, considering the time-dependent electrical, thermal and cooling load demands during the year as constraints, in order to minimize both grid capital and variable costs. The results are presented and discussed in depth and show the strong interaction between fossil and renewable resources, and the importance of an appropriate storage system to optimize the RES impact taking into account the multiproduct character of the grid under investigation.
