Development of test setups for evaluating the quality of laser-cut solar cells

Abstract

The evolving landscape of the solar cell market creates a critical need for adaptation within this changing industry, posing considerable challenges for manufacturers toaddress dynamic shifts. Specifically, the research investigates the impact of these changes on HEI's solar power tube products, underlining the consequence of maintaining competitiveness and innovation in the solar energy sector. With the transition to bigger solar cells wafers, the development of in-house laser cutting capabilities for solar cells becomes a requirement to ensure precise coverage of solarcells within HEI power tubes. To address this, HEI has embarked on an R&D initiative to establish in-house laser cutting capabilities for precise solar cell shaping. To achieve this goal, the establishment of monitoring and testing setups to evaluate the accuracy and precision of the laser cutting procedure is a necessity.The primary objective of this research is to build and develop two in house test setups,Electroluminescence Imaging (EL) test setup for the visualization of loss mechanism and their cause such as cracks. Additionally, a Light Beam Induced Current (LBIC) test setup is introduced, which is a complimentary laser-based testing setup that records current measurements while a laser beam scans across solar cell surface allowing spatial current distribution analysis to aid in the evaluation of different failure types onsolar cell performance.This thesis introduces a carefully structured methodology for designing, building, and assessing experimental setups aimed at evaluating the feasibility of both test setups indetecting different types of failures. The process involves several key steps, carefully followed to achieve the desired objectives. The constructed experimental setups underwent several improvements, including enhancing measurement time and minimizing light reflection effects. These enhancements significantly improved the accuracy of the system's measurements.Various cells were examined using both test setups, the testing encompassed two phases: phase 1, was conducted using solar cells with different failure to establish the proof of concept followed by phase 2 where the testing progressed to diverse scenarios of laser-cut solar cells. The results of all tests have been compared and discussed demonstrating the effectiveness of both testing setups.The findings illustrated the effectiveness of both developed testing setups. The visual data facilitates the identification of potential failures such as but not limited to cracks,edge irregularities, busbar and fingers connectivity issues, and damage resulting from excessive heat during cutting. Additionally, It was indicated that electroluminescence could be utilized as initial screening tool showing an overview of the cell performance while LBIC provided in-depth analysis and classification of defects. This research contributes to ensuring the quality and reliability of HEI cylindrical solar power tubes production process in response to the changing market dynamics.