The influence of hidden cracks on the performance of solar cell modules

　　The three important factors affecting the performance of solar cell modules are hidden cracks, hot spots, and PID effects. Today, we will take you to understand the causes of hidden cracks in solar cells, how to identify and prevent them.

　　1、 The formation and classification of hidden cracks in solar cell modules

　　Hidden cracks are a common defect in solar cell modules, which are subtle cracks that are invisible to the naked eye. Solar cell modules are prone to cracking due to their inherent crystal structure characteristics. In the production process of crystalline silicon modules, many steps may cause hidden cracks in the battery cells. The root cause of hidden cracks:

　　External force: Battery cells are subjected to external forces during welding, lamination, framing, handling, testing, and other processes. Improper parameter settings, equipment malfunctions, or improper operation can cause hidden cracks.

　　High temperature: The battery cells do not undergo preheating at low temperatures, and then suddenly experience expansion after encountering high temperatures in a short period of time, which can cause hidden cracks, such as excessively high welding temperatures and unreasonable parameter settings for lamination temperature.

　　Raw materials: Defects in raw materials are also one of the main factors leading to hidden cracks.

　　According to the shape of hidden cracks in battery cells, they can be roughly divided into five types: dendritic cracks, comprehensive cracks, oblique cracks, cracks parallel to the main grid line, cracks perpendicular to the grid line, and cracks that run through the entire battery cell.

　　2、 The influence of hidden cracks on the performance of solar cell modules

　　The current generated by solar cells is mainly collected and exported by the main and fine grid lines perpendicular to each other on the surface. Therefore, when hidden cracks (mostly parallel to the main gate line) cause the fine gate line to break, the current will not be effectively transported to the main gate line, resulting in partial or even complete failure of the battery cell, and may also cause fragments, hot spots, etc., while causing power attenuation of the component.

　　3、 Methods for identifying hidden cracks

　　EL (Electroluminescence) is an internal defect detection device for solar cells or modules, which is a simple and effective method for detecting hidden cracks. By utilizing the electroluminescence principle of crystalline silicon, near-infrared images of components are captured using a high-resolution infrared camera to obtain and determine the defects of the components. It has the advantages of high sensitivity, fast detection speed, and intuitive and vivid results.

　　4、 The reasons for the formation of hidden cracks

　　There are many factors that can cause hidden cracks in components, and there are also many types of hidden cracks. However, not all hidden cracks will have an impact on battery cells. As long as scientific prevention is taken, hidden cracks in components can be appropriately avoided. During the production process, it is important to avoid improper external forces on the battery cells and also pay attention to the temperature range of the storage environment. During the welding process, the battery cells should be insulated in advance (hand welding), and the temperature of the soldering iron should meet the requirements. In the process of component production, transportation, installation, and maintenance, considering the crack prone characteristics of crystalline silicon components, it is necessary to pay attention to and improve the operation process during the installation of power plants, in order to minimize the occurrence of hidden cracks in components.

　　5、 Key points for preventing hidden cracks in photovoltaic modules

　　During the production process and subsequent storage, transportation, and installation, avoid improper external forces on the battery cells, and also pay attention to the temperature range of the storage environment.