The indoor light sounds pretty silly, I agree.

Do you think there is an appreciable amount of IR, near IR, UV light that it could be worth it? I'm out of date, are we good at harvesting near-ir in photovoltaics? I remember hearing or reading about some frequency upconversion material solutions but it's been a while.

Another problem that comes to mind is the fact that you often want to reflect non-useful-to-vision light rather than absorb it (and heat up).