Abstract
The central role of photovoltaic (PV) systems for the energy transition and the current global geopolitical situation are favouring an PV generation increase across Italy, especially within the South Tyrol's distribution network. The South Tyrol's electricity distribution grid is characterized by sparsely populated and rural areas with a high penetration of intermittent generation where it faces a complex overlap of technical and economic challenges. The integration of renewable sources such as photovoltaics, which are typically widespread in these areas, introduces significant variability in power flows, which may cause problems at both the distribution and the transmission level, thereby affecting the whole national power system. Distribution grids are designed for unidirectional power flows. However, the increasing amount of distributed PV-based generation (especially at “peak hours”) may exceed the actual consumption, thus generating reversal power flows from low voltage towards high voltage. These inversions can saturate the capacity of transformers or the exceed the ampacity of power lines, with a consequent grid congestion. For this reason, due to increasing solar penetration, the saturation of “hosting capacity” (i.e., the capacity of the grid to accommodate new distributed energy resources) especially at the distribution level is more and more common throughout Europe, thereby forcing distributors to constrain new PV installations and/or to subscribe temporary connection contracts that limit the PV-based power supply at critical times. Currently, the solar generation in South Tyrol is entirely generated by small- and medium-sized systems distributed throughout the territory with an installed capacity growth of 11% in 2022 and 26% in 2023. In such conditions, the PV hosting capacity is likely to saturate. In addition, due to solar variability, balancing supply and demand becomes increasingly critical causing over/under voltage events and much steeper load ramps at all time intervals. In this paper, within the context of SustainGRID project, we develop a modelling and simulation framework to identify the areas of the electricity grid with the greatest potential for PV installation and assess their impact in terms of hosting capacity. Initial findings indicate that integrating up to 400 MWp of PV capacity in the 66kV grid by 2030 is feasible without exceeding the voltage limits and with no risk of transformer overloading.