  Micro-structured anti reflective coatings (ARC) have been identified as a
promising solution to reduce optical losses in Concentrator Photovoltaics
modules (CPV). We fabricated and tested in field a CPV modules made of 4
sub-modules with a concentration factor of 250x, that embed either solar cells
with micro-structured encapsulating ARC or solar cells with multilayer ARC as a
reference. The micro-structured encapsulating ARC was made of semi-buried
silica beads in polydimethylsiloxane (PDMS). The module was in operation for 1
year in the severe climatic conditions of Sherbrooke, Quebec, Canada, before
extracting the sub-modules performance under Concentrator Standard Operating
Condition (CSOC). An acceptance angle of +/-0.78 degree was determined for all
sub-modules, demonstrating that improving angular collection at the cell level
has no significant impact on the angle of acceptance at the module level. We
report an increase of 12 to 14% of the short-circuit current and of 15 to 19%
of maximum power at CSOC for solar cells with a micro structured encapsulating
ARC compared to the reference. Despite a sub-optimal module design, we report a
sub-module efficiency of 29.7% at CSOC for a cell with micro-structured
encapsulating ARC. This proves the potential of micro-structured encapsulating
ARC to improve CPV system performance and shows promise of reliability for
sumi-buried microbeads in PDMS as encapsulating ARC.
