Premium PV panels can be worth it if they look better. My parents paid a bit extra for black rather than blue solar panels (said panels also have higher output), and the house really does look a lot better for it. This can matter come sale time; curbside appearance is very important in real estate.
Black backings produce ever so slightly less than white backsheet, and premium panels can technically be worthwhile if you have limited roof space like we do.
I think they are talking about the cells themselves. Black cells have higher light absorption than blue cells (which are reflecting blue light) but I can't speak for their efficiency (and I should note that absorbed light that doesn't generate electricity generates heat which is bad for PV efficiency.)
