Effects Of Fabrication Process On The Mechanical Properties Of EWT Solar Cells

Nowadays, Photovoltaic(PV) has been a key technique of reducing greenhouse effect, and the silicon solar cells are the main products on the PV market. With reducing the cost concern, the silicon solar cell tends to become thinner and more efficient in order to save the consumable material. However, thinning the wafer will cause the degradation of mechanical strength and the increase of breakage which are very detrimental for the performance and yield of silicon solar cell. Meanwhile. In order to increase the solar cell conversion efficient, researchers have developed many back contact solar cells, among which the emitter wrap-through(EWT) solar cell has been paid more and more attention due to its many unique advantages. But different fabrication processes are needed for EWT cells which might degrade its mechanical strength. Moreover, this problem becomes particularly important as a decrease of the wafer thickness for the cost reduction in photovoltaic industry.This dissertation is focused on the mechanical properties of EWT solar cell, including the following aspects.(1)The fracture strength of large size(125×125cm2) silicon wafer, mainly focusing on the effect of laser drilling on mechanical strength of silicon wafer and make a analysis by comparison(2)The effect of texturing, phosphorus diffusion and printing/firing on mechanical strength of generic and EWT solar cells, mainly focusing on the effect of unique back surface fabrication process of EWT solar cell on its mechanical strength(3)The breakage critical value of silicon wafer after different fabricaton process. generic and EWT solar cell under vibration...