PV Penetration Limits in Low Voltage Networks and Voltage Variations

Photovoltaic embedded generation in low-voltage ac networks is quite popular; however, despite its benefits, there are some problems especially when photovoltaic (PV) penetration exceeds certain thresholds. Among others, voltage violation is of prime importance. Our review of the literature focused on PV penetration limits due to voltage violations in low-voltage (LV) networks. The review revealed that voltage violations can occur at a penetration level as low as 2.5% when a large distributed generator (DG) is installed at a single point. Alternatively, a LV network can host a large number of photovoltaic distributed generators (PVDGs), with a penetration level up to 110% if evenly distributed over shorter lengths. However, an LV network has no rules of thumb for safe penetration limits. Penetration-level calculations have been found that they used numerous approaches, which we have analyzed and discussed to adopt a more rational and unified approach. Our literature review revealed that, in LVs, a very high penetration level can be achieved as compared with medium-voltage (MV) networks. However, MV voltage-level control problems impose a limit for PV hosting in LV networks. There is a need to evolve strategies for robust voltage control at the MV level and to develop certain rules of thumb for PV penetration limits in LV networks independent of the MV level, to increase the PV hosting capacity.