Once again, it depends upon what you mean by "yin"? In the Yin Yoga style that we describe here (and is taught by Paul Grilley and Sarah Powers, among many others), we want to deliberately quiet the muscles (the yang tissues) so that we can work the deeper connective (yin) tissues of the body. Sun Salutations require movement, which means engaging the muscles, which in turn means we can not deeply stress the yin tissues of the body.
However! If you are thinking of "yin" as just a quieter way to do a movement based yoga practice, then - yes there are "yin sun salutations". In YinSights, I describe several slower flows, such this mini-sun salutation:
http://www.yinyoga.com/ys2_2.2.7.1.2_mi ... tation.php. Also show is a lovely Cloud Salutation and a Moon Salutation. These flows will not work deeply into the ligaments, joints and bones as do the more classical yin yoga poses, but they are much calmer than most yang sun salutations.
Cheers
Bernie