| Work Detail |
The new solar panels have flexible properties and are suitable for roofs with load restrictions. According to their creators, the modules showed great reliability in both high temperature and high humidity conditions.
Researchers at Japans National Institute of Advanced Industrial Science and Technology (AIST) have fabricated lightweight, curved crystalline silicon (c-Si) solar modules with a polyethylene terephthalate (PET) front cover instead of conventional glass material.
“Our research shows that crystalline silicon solar cell modules with a PET film cover are very reliable under conditions of high temperature and humidity,” Tomihisa Tachibana, corresponding author of the research, told pv magazine . “Although we have not yet calculated the cost of the system, we anticipate that the weight reduction will likely reduce transportation and installation costs.”
In the article “ Development of lightweight and flexible crystalline silicon solar cell modules with PET film cover for high reliability in high temperature and humidity conditions ” reliability under high temperature and humidity conditions), published in Solar Energy Materials and Solar Cells , the Japanese group explained that PET films represent a viable alternative to glass covers, due to their excellent electrical insulation and optical transmittance.
The scientists built the modules with 156 mm2 × 156 mm2 c-Si polycrystalline solar cells with aluminum back surface field structure (Al-BSF) and a thickness of approximately 250 µm. “The busbar chains were connected by mechanical welding, and the chains of the four-cell modules were connected in series by manual welding,” they noted.
They used a 0.025 mm thick PET film for both the front cover of the module and the back sheet and encapsulated the panels with ethyl vinyl acetate (EVA). “The module structure was PET/EVA/Si cell/EVA/PET or backsheet,” they added.
The team compared the thermal behavior of the new module with that of a reference panel that used 3.2 mm thick glass as the front cover material and found that the former showed greater flexibility than that made of glass.
It was also found, however, that the PET-based module has a 10% lower current value, since PET film, unlike glass, has an anti-reflective structure. The stress and fill factor values ??were found to be approximately the same as those of the reference glass module. “The absence of a glass cover also confers flexibility to the manufactured modules, and no cracks or other defects were observed after placing and removing the modules from a measurement scenario with a radius of curvature of 200 mm,” they further explain.
The scientists highlighted that PET film-covered modules also have the advantage of low weight, approximately “a quarter per cell size”, which, according to them, makes them ideal for installation in places with load restrictions. .
They also tested the modules in a series of damp heat (DH) tests at 85 C and under 85% relative humidity and found that the glass-based panel showed a degradation of fill factor and current values ??after 3000 h due to corrosion of the front silver (Ag) electrodes. “On the contrary, the light modules (PET/Backsheet or PET/PET) showed only a slight decrease in IV properties, with a degradation of around 10% compared to the initial value after 6000 h of DH tests,” they stated.
The research group believes that PET-packaged modules, with their shock-absorbing capabilities, can accelerate solar deployment in areas such as weight-limited factory rooftops and agricultural applications. |
