Indeed, though there are other places of the design space to look. For example in satellites, triple junction cells (generating power from additional parts of the spectrum) are worth the much higher cost as they weigh the same as standard cells, thus generating more power without increasing launch cost.

How much more mass, though? Mass is likely to be at a premium anywhere you can't just also slap down a few more cheap cells, e.g. where there's not much space.

Good points by you and your sibling poster. Maybe this tech really would have a hard time finding a niche when considering mass along with cost/performance characteristics, given other premium or economic options. Maybe on the roof of an expensive high rise it would make sense? On boats? Hard to say.