Case study of photovoltaic EVA film encapsulated double glass module

Case study of photovoltaic EVA film encapsulated double glass module

A ground photovoltaic power station is located in the southeastern coastal area of ​​my country. The local climate is hot and humid and salt spray corrosion is serious. After long-term operation of ordinary backplane components, it is prone to problems such as backplane aging and water vapor intrusion leading to cell corrosion. In order to improve the overall reliability of the power generation system, the project uses double-glass components and is encapsulated with highly transparent EVA film.

In terms of scheme design, EVA film with a light transmittance of over 91% is used on both the front and back sides of the module to firmly bond the cells to the front and rear photovoltaic glasses. Since water vapor mainly penetrates from the edges in the double-glass structure, the volume resistivity and resistance to potential-induced attenuation were focused on during film selection to ensure that the leakage current is maintained at a low level in hot and humid environments and to avoid abnormal attenuation of the cell power.

In terms of the packaging process, the lamination temperature is set at 145 to 150 degrees Celsius. The vacuum is first evacuated for about six minutes before lamination. The cross-linking degree is controlled above 75% to ensure that the adhesive film is fully cured and forms a stable bond with the glass. After lamination is completed, the joints are sealed to further block the entry of water vapor.

Three years after the power station was put into operation, the randomly inspected components passed hygrothermal aging and thermal cycle re-testing. The power attenuation was less than 3%. The EL test found no crack expansion, and the appearance of the components was free of bubbles and delamination. This case shows that as long as the materials are properly selected and the workmanship is proper, double-glass modules encapsulated with EVA film can also achieve long-term stable operation in harsh environments, providing practical experience for the construction of power stations in high-humidity and high-salt spray areas.