Techno-Economic Modelling of Solar Photovoltaic (PV) Power Transformers in South Africa

The increasing demand for electricity in South Africa has led to a rise in the deployment of solar photovoltaic systems. The integration of these systems requires the installation of power transformers to convert the generated DC power into AC power that can be fed into the grid. However, the high cost of these transformers can hinder the widespread adoption of solar PV systems. Consequently, the primary objective of this work is to introduce a novel service-lifetime loss estimation method that acknowledges the unique requirements of transformers facilitating solar photovoltaic applications. In reality, these transformers are required to facilitate a sporadic energy source, which advocates for an appropriate method to assess the cost of their service-lifetime losses and total ownership cost. Thus far, the energy elements of classical coal-power generation are inadequate, and in conformity with operational and financial considerations of solar PVs, a novel method incorporating the outcomes of a transformer facilitating a solar PV plant is proposed. The proposed approach has been benchmarked with existing methods and the distinction between proposed and existing methods is highlighted. The study further proposes various regression models for estimating the purchase price for transformers specifically intended to exclusively serve in solar PV applications, which are not available in the current South African standards. The percentage errors between the conventional method and the proposed solar PV method are relatively high, ranging from 34.66% to 44.03%. This indicates that the two methods produce significantly different results, and the proposed solar PV method may not be an accurate replacement for the conventional method.