You may want to investigate PCT -- Porphyria Cutanea Tarda. It's one of the extrahepatic manifestations of liver disease, the development of blisters on areas of the skin that are exposed to sun. There have been threads here about that in the past.
Lapis
I've also noticed some reaction to sun exposure, but I'd describe mine more as hives, isolated bumps, not clusters, that itch some. I sometimes treat with a small dab of benadryl cream if it gets inflamed.
When first starting trt, I thought I might have some issues with the sun, since this seemed to flare up, but it seems to have leveled off. I also lather up with sunscreen for the brutal FL sun and avoid the hottest time of day.