Caution! Risk of Overrating Power in Photovoltaic Modules

PVTIME – In the photovoltaic industry, PERC cells currently dominate the market. Mainstream power testing organizations often benchmark against each other, resulting in minimal numerical differences. Therefore, the space for power overrating is relatively small. However, as TOPCon cells are ramping up production capacity, there is no standardized benchmarking among different testing organizations. As a result, some tested products exhibit significantly higher power than the actual production units, leading to a gradual emergence of power overrating in module outputs.

The rated power of a module refers to its rated output power under standard test conditions and is typically expressed in watts (W). The rated power is just one indicator of the module’s performance and does not fully represent its actual output power, although it is closely related to its electricity generation. Overrating power refers to the practice of exaggerating the actual power of a module and using parameters greater than its actual power to label its rated power. The overrating power can be mainly divided into two categories. One is product promotion, where the advertised power of the module is significantly increased to exceed the achievable limit of module power to attract attention and create hype. The other is product delivery, where low-power modules are falsely labeled as high-power modules and delivered to customers, which in some cases can be considered commercial fraud.

In May and June 2023, the globally renowned photovoltaic exhibitions SNEC and Intersolar Europe were held in China and Germany, respectively. These exhibitions featured numerous high-wattage modules as exhibits that garnered significant attention. The rated power of modules from various manufacturers ranged from tens of watts to over 700 watts. It is an abnormal phenomenon to have such a wide variety of module powers when the industry has similar production cell and module conversion efficiencies, and the module sizes are not significantly different. Some manufacturers showcased 182-72c modules with a power output as high as 620Wp and 210-66c modules with 740Wp. The corresponding module conversion efficiencies were 24% and 23.9% respectively, which is quite exaggerated. Considering the efficiency losses in the cell-to-module (CTM) process, the corresponding cell efficiencies would need to be close to 27%. Currently, the highest laboratory efficiency record for crystalline silicon cells is only 26.81%, indicating the significant challenges in mass-producing modules with such high-power outputs.

Figure-Maximum power and corresponding conversion efficiency of the 182-72c and 210-66c modules

In terms of product delivery, due to the direct correlation between module prices and power output, some small module manufacturers are focused on short-term gains. They may even intentionally seek institutions that can provide higher evaluation data. This undoubtedly undermines the fair competitive environment in the market and imposes inflated costs on downstream customers. If top manufacturers also imitate this practice to attract customers with modules claiming higher power outputs, it will ultimately harm the entire photovoltaic industry. Currently, the mass production conversion efficiency of mainstream p-type PERC modules is around 21.3%, corresponding to a power output of 550Wp for 182 modules and 660Wp for 210 modules. The conversion efficiency of mainstream n-type TOPCon and HJT modules is close to 22.1%, corresponding to a power output of 570Wp for 182 modules. Due to the existence of a limited capacity of high-efficiency cells, the power output of modules made from these cells can be increased by 5-10W. Although this output is relatively small and paying attention to the manufacturer’s delivery capabilities is necessary, it still falls within the range of real efficiencies and power outputs. However, modules that claim to have a power output of 20W or even higher than the current mainstream production require us to retain some doubts.

Industry experts believe that the core competitiveness of the photovoltaic industry should focus on technological innovation and invest in research and development from the foundational level. The advice is to resist the temptation of pursuing short-term gains and instead, embrace a long-term perspective. In the future, the photovoltaic industry and companies should establish industry standards. In the absence of unified national standards, major industry players should collaborate and gradually promote standardization of module sizes to prevent industry saturation and unnecessary resource waste. Similarly, unified module testing standards require not only self-discipline from leading companies in the market but also concerted efforts from industry associations and relevant government departments to drive the establishment of unified standards across various segments of the photovoltaic industry. By following this approach, the industry can foster stable and sustainable development, promoting a healthier business environment.