Logic and physics agree paint reduces heat transfer and black will
absorb solar radiation. Whether it can be rated on an AC? Paint a piece
of wood black, one silver, the black at 0 f wil be 50-60 in calm full
sun , the silver under 10f. Ive done it. At 80f black will be over 120
silver near 90f Paint reduces heat transfer, but type of paint and
thickness determine amount. Maybe on old cheaper units it was done ?
Measurable amount of loss ? But I would think so. Just as I wouldnt
put a unit in full sun where temperatures are 20-40+ hotter. It doesnt
matter some will say , well then why are newer shakers flipping water
back into the coils. I have a lake 20 ft away I wish I could submerge
my coils in 20ft of 60f water, I figure every little bit helps.