The CTC (China Testing & Certification International Group) Hainan Empirical Base has released its three-month test results from October to December Under high-temperature and high-humidity conditions, HJT (Heterojunction) PV modules outperformed BC (Back Contact) modules in power generation per watt, with an average increase of 2.97% and a maximum daily increase of 14.18%.
Haikou, the capital of China’s southernmost Hainan Province, boasts a tropical climate with year-round sunshine. Its average annual horizontal irradiance is 1,368kWh/m², temperature about 24.4℃, and relative humidity as high as 80.9%. These high-temperature, high-humidity conditions present a challenge to the reliability of photovoltaic modules, potentially affecting components like encapsulation, back sheets, and junction boxes, as well as accelerating power decay and worsening the PID effect.
Conducting the HJT outdoor empirical project in Haikou will verify HJT’s long- term performance under these extreme conditions, supporting its large-scale application in tropical and subtropical regions and advancing the global photovoltaic industry.
For this empirical project, 210 HJT and 182 BC modules were selected, with 8 units of each type installed. They were mounted horizontally on fixed-tilt racks in a single row, with a tilt angle of 20 degrees, a height of 1.65 meters above ground, and a spacing of 2.6 meters between rows.
To ensure a fair testing environment, additional modules were installed in front and behind the test arrays to eliminate shading differences. High-precision sensors recorded data on irradiance, module back sheet temperature, ambient temperature, humidity, and atmospheric pressure, with a 1-minute sampling interval.
We used PVsyst to simulate the annual power generation of HJT and BC modules at the Haikou project site. The line chart below shows the trend of power generation increase for HJT compared to BC. The results indicate that the increase in power generation from HJT is seasonal, with a larger boost in summer and a smaller increase in winter.
During the test, we compared the power generation of HJT and BC modules under various weather conditions. The results showed that from October to December 2024, HJT modules consistently outperformed BC modules, with a maximum daily increase of 14.18% on a rainy day.
Over the three-month period, the normalized power generation of HJT modules reached 291.68 kWh/kW, compared to 283.26 kWh/kW for BC modules. This represents a 2.97% higher average power generation per watt for HJT modules. Based on both test and simulation data, we can infer that the power generation increase for HJT will be even greater in summer. In high temperature, high-humidity regions, HJT modules offer higher power generation, providing greater benefits to customers.
