Influence of the change direction of total solar irradiance at the inclined surface on power generation performance of photovoltaic power station: A focus on output power and photoelectric conversion efficiency

This study investigates the role of the photovoltaic (PV) industry in the economic development of desert areas, particularly on the current international research hotspot of improving the power generation performance of PV power plants. We investigate how changes in the direction of total solar irradiance (Gp) on inclined surfaces affect output power (P), system efficiency (ηs), and photoelectric conversion efficiency (ηe) of desert PV power plants. Additionally, we introduce a novel metric called the influence degree (ID) to quantify how trends in the increase or decrease of Gp affect P. Experimental data from a 100.00 MWp desert PV plant in Inner Mongolia, China, reveal that P, ηs, and ηe were consistently higher during Gp decline phases than during the rise phases under identical irradiance levels. The ID exhibits linear negative correlation (200.00–955.00 W/m2) and nonlinear accelerated decay (25.00–200.00 W/m2) with Gp. Key findings include a 3.62 % higher average power growth rate during Gp decreases and a narrowed ηe distribution range in decline periods compared to rise phases. This work provides actionable insights for optimizing PV plant operations in arid environments, emphasizing the critical role of irradiance directionality in performance prediction. The proposed ID metric bridges a gap in utility-scale PV analysis, offering a tool to enhance energy yield and economic returns in desert solar projects.