全球领先的背板供应商康维明日前表示，该公司可为一些特殊的组件制造商提供可降低光伏组件“蜗牛纹”的低水汽透过率背板，日前通过光伏最权威机构德国晶硅光伏CSP弗劳恩霍夫中心的蜗牛纹模拟测试。 近年来，被称为“蜗牛纹”的缺陷是太阳能光伏组件制造商遇到的最麻烦的问题之一。 “蜗牛纹”通常出现在太阳能电池上，在电池边缘或电池间的微裂纹中产生变色现象，呈现褐色的视觉效果。 研究发现，如果水分通过电池的微裂纹或电池的边缘渗入，可能使银离子产生反应，从而产生具有典型呈褐色状的银纳米粒AgNP。当这些纳米粒积累到一定的程度后引起的变色现象，被称为“蜗牛纹” 康维明表示，尽管背板材料与蜗牛纹之间是否有直接关系尚未被证实，然而业内已经意识到降低背板的水汽透过率WVTR可减少水分渗入电池边缘和微裂纹。这就是为什么康维明研发了含有特殊助料层的背板使得水汽透过率WVTR小于2克每平方米·天 (38 ℃/90% 湿度， Mocon Permatran)。 另外，康维明解释，如果封装材料和背板中含有S、Se和Cl等特殊的元素的有机金属化合物，也会可能导致在电池表面产生AgNP，从而导致“蜗牛纹”的出现。 康维明已经把含上述特殊助料层的背板样品递交给研究蜗牛纹的最高权威机构-德国晶硅光伏CSP弗劳恩霍夫中心，用以进行晶硅电池的蜗牛纹研究。该中心通过研究太阳能电池上银纳米粒子AgNP的存在，测试背板是否会引发蜗牛纹的形成。 测试发现康维明的所有背板和层压件样品均不含有银纳米粒子AgNP，也就是说康维明背板对蜗牛纹是不敏感的，因此适用于在抗蜗牛纹的光伏组件中进行使用。 In recent years the defect known in the PV sector as "snail trails" or "snail traces" has been one of the most troublesome issues for most PV module producers. "Snail trails" usually appear on the PV cells as dark streaks which are the visual result of a brownish color discoloration of the cells grid fingers occurring along the cell edges or close to cells micro-cracks. According to the most valuable theories and experiments, if some moisture manages to reach the cells through these micro-cracks or cell edges the water might trigger a reaction with the silver ions contained in the grid fingers therefore creating some Silver nanoparticles (AgNP) with a typical brownish color. When these silver nanoparticles get accumulated in the area of the encapsulation foil directly in contact with the grid fingers they then cause the discoloration phenomenon known as "snail trail". Even though a direct correlation between backsheet material and snail trails hasn't been proven yet, it is common knowledge that reducing the WVTR (Water Vapor Transmission Rate) of the backsheet could consequently decrease the chances of moisture transmission through cell edges or micro-cracks. That's why Coveme developed a backsheet with a special primer which provides a WVTR of <2 gr/sqm. per day (38 C/90% HR with Mocon Permatran). Besides that, there might be chances for the encapsulation materials and for the backsheet to facilitate the formation of "snail trails" if these materials contain some organo-metallic compounds with some specific elements like S, Se and Cl. These compounds can lead to the formation of AgNP on the cells surface. Samples of Coveme backsheet with above mentioned special primer were then submitted to the maximum authority for snail trail studies, the Fraunhofer Center for Silicon Photovoltaics CSP in Germany. Fraunhofer CSP developed a test to evaluate whether the backsheet could trigger the formation of snail trails considering the presence of Silver nanoparticles (AgNP) on the cells. All single samples and all laminated samples of Coveme backsheets were considered negative in this AgNP test, leading to the conclusion that Coveme backsheet is not snail trail sensitive and it is therefore suitable to be used in PV modules for anti-snail trail properties. |
