Abstract:
Electroluminescence (EL) is a useful characterisation tool for
the early detection of performance limiting defects such as
micro-cracks, unwanted impurities inside photovoltaic (PV)
module cells and grain boundaries[1][2]. Most micro cracks
result from the manufacturing process, transportation, and
handling during storage and installation. After deployment,
micro cracks can become more severe due to thermal cycling
and dynamic wind loading. In order to correctly interpret EL
images and be able to compare images taken at different
degradation stages, the images need to be taken under similar
resolution, integration time, applied current as percentage of
short circuit current and environmental conditions. This paper
discusses these settings and how best to optimise them to
efficiently and accurately image degradation present in PV
modules. The modules used in this work are two
monocrystalline modules (A and B of 60 and 72 cells
respectively). Degradation of PV modules such as Potential
Induced Degradation (PID) or micro-cracks can affect the
long-term reliability and profitability of PVinstallations. This
paper describes and identifies the optimum settings (camera
and voltage bias) at which module performance degrading
defects and resistive properties may be observed. The EL
method is fast and non-destructive and can be used to assess
modules prior to deployment.
