Shingle Cell IV Characterization Based on Spatially Resolved Host Cell
Measurements
Abstract
Each solar cell is characterized at the end-of-line using
current-voltage ( IV) measurements, except shingle cells, due to
multiplied measurement efforts. Therefore, the respective host cell
quality is adopted for all resulting shingles, which is sufficient for
samples with laterally homogeneous quality. Yet, for heterogeneous
defect distributions, this procedure leads to (i) loss of high quality
shingles due to defects on neighboring host cell parts, (ii) increased
mismatch losses due to inaccurate binning and (iii) lack of
shingle-precise characterization. In spatially resolved host
measurements, such as electroluminescence images, all shingles are
visible along with their properties. Within a comprehensive experiment
840 hosts and their resulting shingles are measured. Thereafter, a deep
learning model has been designed and optimized which processes
host-images and determines IV parameters like efficiency or fill
factor, IV curves and binning classes for each shingle cell. The
efficiency can be determined with an error of 0 .06 % abs
enabling a 13 % abs improvement in correct assignment of shingles to
bin classes compared to industry standard. This results in lower
mismatch losses and higher output power on module level as demonstrated
within simulations. Also IV curves of defective and defect-free
shingle cells can be derived with good agreement to actual shingle
measurements.