Fig. 2 shows three CdTe mini-modules encapsulated using
EVA sheets of three different colors. The results of the
electrical characterization of CdTe devices using single-color
EVA add-on layers were reported in [8]. It was shown that an
overall positive impact to efficiency can be achieved for a
broad range of colors. This range is broader for CdTe devices,
due to their relatively poor response for λ deeper into the
visible region of the spectrum compared to other PV
technologies such as those of mc-Si or CIGS.
Table I gives the xyY coordinates in the CIE 1931 color
space of the samples shown in Fig. 2. These measurements
were taken at a viewing (or measuring) angle perpendicular to
the plane of the devices. However, note that the chromaticity
results were almost independent of the viewing angle, for
angles almost down to 15° in respect of the devices’ plane.
This was not the case for the luminance coordinate, which was
lower for smaller angles with a maximum value for 90° (the
value reported in Table I). The retention of same (or at least
very similar) chromaticity for different viewing angles is a
feature that can be advantageous in certain applications. The
same is not true when illuminating with a different spectrum
(for example standard indoors halogen lighting versus sunlight
or AM1.5G), in which case the deviation in chromaticity
becomes much more significant.