What is the Value of BC? – A Field Investigation of Multi-Climate BC Second Generation Photovoltaic Power Stations
In March, the coastal winds of the Jiaodong Peninsula welcomed the reporters to the Yantai BC verification station, where sunlight was being converted into abundant green electricity through photovoltaic technology. This scenario is being replicated across six major climate zones in China: from the Yellow Sea to the South China Sea, from the snowy north to the Yunnan-Guizhou Plateau, as BC components establish a “stress test” for photovoltaic efficiency throughout the country. Under the strategic push to accelerate the construction of a new power system, an empirical examination regarding the choice of photovoltaic technology routes is quietly unfolding.
Salt Mist Erosion Defense
Yantai, located at 37°N, experiences a warm temperate East Asian monsoon climate, with an average of 2300 sunshine hours annually, categorizing it as a region with moderate solar energy resources. Given the limited solar resources, the conversion efficiency of photovoltaic components becomes critical. The power generation curve displayed on the monitoring screen at the Yantai BC project reveals significant breakthroughs in component efficiency: during the monitoring period from September to November 2024, Longi Green Energy’s second generation BC products achieved an average power generation gain of 2.93% over TOPCon products.
Upon arriving at the Yantai BC station, the first noticeable feature is the salty sea breeze, a common challenge for coastal photovoltaic stations due to high salinity and moisture. The second generation BC photovoltaic components have successfully passed rigorous testing for resistance to acidic copper accelerated salt mist corrosion at level 8, ensuring reliable and stable power generation in coastal and marine environments.
Transition to Offshore Projects
The trend of shifting renewable energy project development towards offshore sites is becoming evident in Yantai. In April 2024, the Ministry of Natural Resources released management documents guiding the development of offshore photovoltaic projects. In November, the Shanghai Municipal Development and Reform Commission announced a competitive configuration plan for offshore photovoltaic projects, specifying performance requirements, including a minimum component conversion efficiency of 23%. The BC second generation photovoltaic components, with an efficiency of 24.43%, demonstrate a clear advantage.
Efficiency Breakthrough in Low Light Conditions
In Kunming, the “Spring City” of Yunnan, which sees an annual rainfall of 900mm, the warm and humid climate presents challenges for photovoltaic systems, especially during the rainy season when sunlight is scarce. Monitoring data from a rooftop verification project in Yunnan during the rainy season of 2024 indicates that the actual power generation per unit area of BC second generation components exceeds that of TOPCon by 5%. “This is due to the excellent spectral response rate of BC second generation products,” the product solutions manager from Longi Green Energy explained, referencing the certification report from the international testing authority TÜV Rheinland. “In regions like Yunnan, where there is abundant water but insufficient light, the weak light performance of photovoltaic components is particularly vital. The spectral response rate of BC second generation products can lead TOPCon by up to 44%, akin to equipping the components with a ‘light sensor’.” Data from October to November shows that the power generation per watt from BC second generation products is 3% higher than that of TOPCon and 5% higher than HJT.
Shadow Management in Wind-Solar Complementarity
In Yinchuan, the complementary use of wind and solar energy can lead to efficient utilization of spatial resources. However, the shadow cast by wind turbine towers can obstruct the surface of photovoltaic components, potentially causing hot spot issues that affect power generation efficiency. At a photovoltaic project in Yinchuan, white vertical poles cast slender shadows as part of a specially designed test to simulate the wind-solar complementary scenario.
Empirical data from September to October 2024 reveals that the second generation BC products exhibit exceptional shadow management capabilities: when partially shaded, the changes in voltage and current are minimal, resulting in an overall power generation gain of 18% over conventional TOPCon components, exceeding 30% under high irradiance conditions. Engineers explained that conventional photovoltaic components experience significant losses when encountering shading, akin to “vascular blockage,” while the BC second generation cell technology features a “weak conduction” design, allowing each cell to be controlled independently. When shaded, the cells can bypass themselves, ensuring that the entire module maintains high power generation capability.
Future Development Plans
Recently, the Shaanxi Development and Reform Commission issued a notification regarding the development of wind and photovoltaic projects in the province for 2025, planning to implement approximately 2GW of the “Photovoltaic Leading Plan.” Projects applying for the plan must have components with a conversion efficiency of over 24.2%, and the BC second generation photovoltaic components, with an efficiency of 24.43%, surpass this threshold.
Performance Under Extreme Conditions
In Sanya, Hainan, the verification base at the Jianheng Certification Center features tall posts casting shadows in the bright sun. This area, located in a low-latitude tropical region, enjoys abundant sunlight throughout the year. The verification site consists of four component arrays (20 Hi-MO 9 and TOPCon components each), with two arrays designed for shadow testing and two without shading. After 18 days of continuous shading, the BC second generation components demonstrated impressive performance. According to the Jianheng Certification Center’s research institute, the Hi-MO 9 BC second generation photovoltaic components achieved a cumulative power generation gain of 11.34% per kilowatt and a unit area gain of 16.27%, with the average temperature of the BC component backsheet remaining approximately 0.83°C lower than that of TOPCon components, showcasing remarkable efficiency.
Beyond shadow impacts, the BC second generation components consistently outperformed TOPCon components in both outdoor normal power generation and under partial shading conditions, with cumulative power generation gains of 0.75% and 32.62%, respectively, demonstrating strong overall generation capabilities.
High Humidity and High Temperature Performance
In Taizhou, Jiangsu, located at 32°N, the humid and hot airflows from the Yangtze River Delta pose challenges. During a visit to the Taizhou verification station, reporters experienced an afternoon thunderstorm, with humidity rising from 65% to 92% in just 15 minutes while temperatures remained at 38°C. “This can be described as a ‘sauna mode’ for the components,” a technician from Longi explained. “The humid environment can induce PID (Potential Induced Degradation) effects, leading to power losses.” The performance of the BC second generation components was encouraging: from March to October 2024, cumulative power generation reached 3767.71kWh, surpassing TOPCon’s 3484.11kWh by 8.14% under the same design conditions. “The secret lies in the power temperature coefficient of BC2.0 components at -0.26%/°C,” the technician pointed to the thermal imaging data. “Conventional TOPCon products have a power temperature coefficient of -0.28%/°C, resulting in greater power loss and less power generation under the same temperature increase.”
Reliability Under Extreme Climate Conditions
In Dongfang, Hainan, situated at 18°N, the tropical monsoon climate results in distinct wet and dry seasons, with abundant sunshine and an average daily sunshine duration of up to 9.5 hours, creating an optimal power generation environment. Data from the Huaneng Gezheng highway photovoltaic corridor demonstration project shows that BC components outperform in terms of power by 25W, with a 1% higher conversion efficiency and an average power generation per watt exceeding that of TOPCon components by 2%. Furthermore, the BC components demonstrate superior performance in annual degradation, temperature coefficients, shading tolerance, and weak light performance. The BC second generation components also offer cost savings on steel pile foundations and wiring materials, resulting in a higher return on investment compared to TOPCon.
Conclusion: Efficiency Transformation Across Latitudes
The empirical journey from Yichun to Hainan reveals a clearer trajectory of technological advancement in the photovoltaic industry through data from six stations. In terms of conversion efficiency and reliability, the BC second generation photovoltaic components achieve a high conversion efficiency of 24.43%, capable of withstanding extreme heat and humidity, while still generating power efficiently under uneven light conditions. Currently, over 20 BC verification stations are established nationwide, with continuous data coming in from various temperature zones. The “power generation gain” of photovoltaic components should not merely remain on product specification sheets but should be reflected in the actual power generation data from photovoltaic stations. Across the nation, BC photovoltaic stations in various application scenarios are being completed and put into operation, and reports will continue to follow this story—where the fluctuating power generation data acts as an “electrocardiogram” for the stations, and whether the BC second generation photovoltaic components can ensure a steady and robust performance remains to be seen. Based on the current data, this presents a promising outlook.
