Profitability of Solar Photovoltaic Projects: A Sensitivity Analysis of Performance Loss Curves and Operation and Maintenance Expenses

Literature highlights the fact that degradation curves are frequently not linear. This technical knowledge is, however, neglected by developers, which continues to use simplified linear degradation rates to assess the profitability of solar photovoltaic (PV) projects. Herein, the unleveraged equity interest return rate (IRR) of utility-scale (50 MWp in size) PV projects deployed in different parts of Europe is computed and a sensitivity analysis of how the profitability of the plant is impacted when nonlinear degradation curves are used is carried out. In general, a 2-step performance loss curve leads to the highest project-IRRs at equal total loss, whereas the lowest IRRs are achieved if module degradation is undergoing a negative logarithmic or exponential curve. Further, the sensitivity of profitability to the different degradation trajectories increases at higher latitudes for which the absolute project-IRR is lower. Then, a similar analysis is performed mimicking situations that would lead to a significant revamping of the PV plant after 10 years of operation. This allows us to identify thresholds for overall module degradation that would justify this kind of intervention. Finally, the impact that loss rates and combined operation-maintenance and insurance costs have on the project IRR is highlighted.