Improved edge isolation of solar cells applying readily dispensable etching paste
An advanced and cost effective process for edge isolation of silicon solar cells by strongly local deposition of etching paste isishape SolarEtch® SiD is presented. The deposition of the paste was carried out by deposition technique being free of contact to substrate, namely dispensing. Basic deposition parameters were figured out and later on refined by design of experiment applying elaborated sub-design. In order to evaluate isolation properties of the new process, experimental trials focusing on process step of edge isolation of standard solar cells were conducted by applying different deposition conditions. For this purpose, experimental trials were sub-divided into two phases: firstly, evaluation of new concept and secondly, its validation by applying industrial conditions of mass production. Conventionally isolated wafers, e. g. by laser scribing, were taken as reference. Comparison of paste-isolated batches with reference batches provided clear evidences for improved cell performances after isolation by etching paste over reference batches. The main beneficial factor for improving solar cell's performances was identified to originate from increased values of JSC. Isolation process by paste was supplemented by ES&H considerations which provided evidence for environmentally friendly process conduction being superior to single side etching.