Comparison Of Mainstream Solar Panel TOPCon and BC Rooftop Empirical Data For One Year
Data source: Photovoltaic News
N-type TOPCon cells have become the mainstream product in the market with excellent efficiency and reliability, with a market share of about 80% in 2024. Despite this, in order to achieve product differentiation and enhance product value in the fiercely competitive market, many photovoltaic companies have turned their focus to BC-type monofacial modules and made them the main products in the rooftop photovoltaic market.
BC modules are theoretically very suitable for rooftop installation applications due to their high front power output. In the rooftop installation environment, the bifacial disadvantage of BC cells can be significantly alleviated. Recently, JinkoSolar announced that it has carried out a comprehensive field test study in Jiangxi.
Jiangxi's monsoon humid climate and average temperature of -5 to 35°C throughout the year provide ideal natural conditions for evaluating the performance of different photovoltaic modules. This will help to deeply understand the performance of various modules in actual applications, thereby providing a scientific basis for future product development and market strategies.
Module information
This study covers TOPCon modules and BC modules produced by a certain manufacturer. All modules are installed on the roof of the building to ensure the accuracy and consistency of the measurement data. The core goal of this study is to deeply analyze the performance and LCOE potential of these two components in actual applications, and provide customers with reliable and efficient power generation solutions. The test involved two types of components: N-type TOPCon components with a nameplate power of 575W and BC components with a nameplate power of 575Wp from another manufacturer, with 18 of each component. They were installed on a fixed bracket with an inclination set to 0°. All components were equipped with high-precision sensors to monitor power generation data in real time to ensure the accuracy and credibility of the test results.
During the test, a number of key data were fully collected, including DC voltage, current, power, component temperature, front radiation, wind speed, wind direction, ambient temperature, relative humidity and atmospheric pressure. These data provide detailed information, allowing us to conduct in-depth analysis and comparison of the performance of the components.
Test Results
Some significant climate and performance changes were observed in the 11 months from August 14, 2023 to July 15, 2024. The highest daily average irradiance recorded in June was 273W/m², and the highest temperature recorded in July was 39.7°C. The lowest irradiance of 104W/m² and ambient temperature of -5°C were recorded in January and February, respectively. Frequent rainfall in April 2024 (20 rainy days) led to a decrease in irradiance, which in turn affected the power generation of the modules. Even under such continuous rainy conditions, the power generation of TOPCon modules was 0.33% higher than that of BC modules. However, with the arrival of high temperatures and long days in June, TOPCon modules showed their excellent performance, with a 1.95% increase in power generation compared to BC modules. This significant gain not only proves the adaptability of TOPCon modules in high temperature environments, but also highlights their high efficiency in summer.
In addition, during the snow season from January to February, under the dual influence of low irradiance and low ambient temperature, the power generation of TOPCon modules was 0.52-0.53% higher than that of BC modules. This data further confirms the superior performance of TOPCon modules in cold climate conditions, especially in winter when light and temperature are low. The test results show that TOPCon modules have significant advantages in power generation efficiency, with the power generation per watt being up to 1.95% higher than that of BC modules during the test cycle, which is attributed to its higher power generation capacity (kWh/kW) and high reliability during the overall cycle.
This result fully demonstrates that even without considering the bifaciality factor, TOPCon modules still perform better in rooftop applications, reducing initial investment costs and LCOE while improving power generation and product performance.
Data Analysis
The reason why TOPCon modules can achieve higher power generation is mainly due to their lower operating temperature. This allows it to maintain a high power generation efficiency in the high temperature environment in summer when other modules generally reduce power generation due to temperature coefficients, thereby achieving higher power generation gains per watt. During the test, the average operating temperature of TOPCon modules was always lower than that of BC modules from other manufacturers. When the temperature coefficient of both modules is about -0.29%/°C, the power generation attenuation of BC modules due to high temperature is significantly higher than that of TOPCon modules.
In principle, BC cells expand the effective power generation area by transferring the electrode grid lines on the front of the cell to the back of the cell. This design has obvious advantages in improving the cell conversion efficiency in rooftop photovoltaic systems that do not rely particularly on bifacial power generation. However, this design also brings some challenges. In practical applications, the concentration of stress on the back of the BC module causes the surface of the module to bulge and bend, which in turn affects its reliability and efficiency. This phenomenon is particularly obvious in June and July. When the maximum temperature can reach 37°C, the surface temperature of the module may even exceed 60°C at noon. This high temperature environment not only affects the power generation efficiency of the BC module, but also may accelerate the aging of the material, thereby affecting the long-term reliability and performance of the module.
Summary
This study records and compares the performance of TOPCon modules and BC modules in a rooftop application scenario over a one-year cycle. Through this comparison, the purpose is to evaluate the relative competitiveness of the two in terms of cost-effectiveness and energy output. The results reveal the following key findings:
1) TOPCon modules, with their higher power generation capacity (in kilowatt-hours per kilowatt), are up to 1.95% higher than BC modules in terms of front power generation. Even if we ignore the advantages of its bifacial power generation, TOPCon still shows stronger potential in rooftop applications.
2) The study found that there is a significant linear correlation between irradiance, temperature and power generation for the two modules. Specifically, as irradiance and temperature increase, the power generation gain of TOPCon modules is particularly significant.
3) TOPCon modules show better performance under low light conditions in the morning and evening. This is particularly important in practical applications because it means that TOPCon modules can more effectively utilize limited light resources during periods of short sunshine time.
Based on these data, JinkoSolar recommends that further power generation efficiency testing and monitoring research should be carried out in the future to provide users with more scientific and accurate solutions.