> In particular, a school in a valley in the UK having its lights on doesn't on really seem like a big deal as long as they're using LED lights. Attempting to harness natural light in this type of building sounds like a feel-good notion that can't possibly compete with decent led lighting run from a renewable grid.

Maybe that's just me, but natural light is way better for my mental health than artificial light. Being forced to depend on artificial light makes me feel like I'm in a basement, which I don't like at all.