Skylights BFD
More than a sky light, more like a deck prism. Much better illumination than a mere hole in the roof.
It’s not a BFD to the likes of you and me who have ready access to cheap and reliable electricity, but for most of the world it really is a BFD.
That was my question too. Also, how well does this work in the winter when they freeze? How well does it insulate? And I doubt they last very long before leaking starts considering the degradation of plastic from UV and the constant expansion and contraction associated with the warming and cooling.
Also, what if you don't have cathedral ceilings for the "water filled skylight"? Who thought this was a good idea again?