The four factors that affect the capacity matching ratio of a photovoltaic power station
The capacity matching ratio of a photovoltaic power station can improve the overall utilization efficiency of the photovoltaic system, reduce the system’s cost per kilowatt-hour (kWh), and increase profitability. So, what are the four factors that affect the capacity matching ratio of a photovoltaic power station?
Module Degradation
Under normal aging degradation, the module’s degradation rate in the first year is about 1%, and after the second year, the degradation will follow a linear trend. The degradation rate over 30 years is about 13%. Therefore, the design of the photovoltaic capacity matching ratio needs to take into account the module degradation over the entire lifecycle of the power station to maximize the matching of the module’s power generation and improve system performance.
System Losses
In a photovoltaic system, there are various losses between the photovoltaic modules and the inverter output, including losses from module series/parallel connections, shading, dust, DC cable losses, and inverter losses. These losses will affect the actual output power of the inverter in the photovoltaic power station.
As a result, there is a loss discrepancy between the installed capacity of the photovoltaic modules and the actual power generation data. If the inverter is chosen with a 1:1 matching ratio based on the module’s installed capacity, the actual output capacity of the inverter will be about 90% of the inverter’s rated capacity. Even under optimal sunlight conditions, the inverter will not operate at full load, which reduces the utilization rate of both the inverter and the system.
Different Solar Irradiance in Different Regions
Modules can only reach their rated power output under Standard Test Conditions (STC) (STC conditions: irradiance intensity of 1000 W/m², module temperature of 25°C, and air mass 1.5). If the working conditions do not meet the STC, the photovoltaic modules' output power will inevitably be less than their rated power.
Module Installation Angle
For user-side photovoltaic power stations, there will be different roof types within the same project. Different roof types correspond to different module installation angles, which affect the amount of irradiance the modules receive.