  Colored solar cells suffer from lower efficiency due to reflection and
absorption losses by coatings. By studying different types of coatings on solar
cells, the spectrum parameters impacting the solar cell efficiency were
identified. A collection of color coatings was fabricated and characterized
using spectrophotometry and colorimetric photography. The coatings include
commercial absorption filters, commercial distributed bragg reflectors,
lab-made interference coatings, and cellulose nanocrystal coatings. Commercial
single junction and multijunction solar cells were used to measure the impact
of the color coatings on solar cell performance. Structural colors were found
to result in the highest brightness to color loss ratio. Structural colors do
not fade provided that the structure is not compromised. Color loss in single
junction solar cells is a result of the proportion of reflected light in the
absorption range of the material. Multijunction solar cells were strongly
affected by current mismatch losses, where narrow reflection peaks resulted in
high efficiency losses. Structural color coatings made using cellulose
nanocrystals exhibited low and broad reflection peaks that produced bright
colors and maintained high performance of single junction and multijunction
solar cells, retaining up to 83 % of the reference power obtained in the
absence of a color coating.
