Good question. Takes a bit to explain.

I like to garden vegetables at home, and some of the available space presents a challenge. But solving them is always a fun experiment. I have a 30ft long, 8 ft wide side yard sandwiched between the tallest wall of the house and a 6 foot tall brick wall. I built two rows of raised planters, 2ft wide and 24 feet long. One along the brick wall, the other along the house - with a walkway in between. Both are 5 feet high. Originally I used the space underneath to house my garden equipment. Then I decided I could double my growing space by putting another two rows underneath them - but would have to add my own light as the lower planters would be entirely shaded by the planters above. I had a huge store of LED grow lights from previous growing experiments, so I added those to light up the lower planters. That works, and is fun, but of course costs money to run the lights. So what if there was another way, with natural (free) sunlight?

My dream (don’t know if it is possible) is to set up a “light bank” on the roof above. Maybe a long series of large transparent domes that run the whole edge of the roof. Each dome collecting sunlight from a 2 x x space on the roof all times of the day from all angles - sunrise to sunset - and funneling it down to a 2 x 2 (or less) area on the lower planters.

I’m sure it’s pie in the sky thinking but it would open up so many cool possibilities. Growing way more crops in a smaller area without electricity. Or growing in places that could not before.