Modern low-voltage distribution systems necessitate solar photovoltaic (PV) penetration. One of the primary concerns with this grid-connected PV system is overloading due to reverse power flow, which degrades the life of distribution transformers. This study investigates transformer overload issues due to reverse power flow in a low-voltage network with high PV penetration. A simulation model of a real urban electricity company in Ghana is investigated against various PV penetration levels by load flows with ETAP software. The impact of reverse power flow on the radial network transformer loadings is examined for high PV penetrations. Using the least squares method, simulation results are modelled in Excel software. Transformer backflow limitations are determined by correlating operating loads with PV penetration. At high PV penetration, the models predict reverse power flow into the transformer. Interpolations from the correlation models show transformer backflow operating limits of 78.04 kVA and 24.77% at the threshold of reverse power flow. These limits correspond to a maximum PV penetration limit of 88.30%. In low-voltage networks with high PV penetration; therefore, planners should consider transformer overload limits caused by reverse power flow, which degrades transformer life. This helps select control schemes near substation transformers to limit reverse power flow.

Distributed generation has enhanced power production in recent times. Due to their benefits, Ghana is interested in grid-tied solar photovoltaic (PV) systems. Despite the benefits, solar PV integration studies in Ghana have not advanced. This study examines reverse power flow (RPF) due to solar PV in Low Voltage (LV) network branches. The methodology uses a modified IEEE European test network and an Electricity Company of Ghana (ECG) LV network. ETAP software is used to simulate the two solar PV integrated LV networks, and the obtained data is used to formulate correlation models of solar PV penetration and key network parameters in Excel. Model results estimate the RPF critical values for the modified IEEE European test network and the ECG LV network as 7.36 kW and 7.44 kW, respectively. The RPF values are obtained at maximum penetration depths of 62.6% and 69.8% respectively. At maximum penetration levels, predicted line loadings are 6.42% and 7.28% respectively. Further analysis reveals branch-transformer RPF margins of 26.8% and 23.1% in the modified IEEE European test network and the ECG LV network respectively. The results are essential for establishing pre-determined settings to safeguard LV network branches and transformers from overload due to RPF.INDEX TERMS Safe margins, low voltage network, reverse power flow, simulation data, solar PV, threshold parameters.