Here’s a way to brighten up enclosed spaces in an environmentally friendly way. The power of the sun is harnessed using a bottle full of water. Quite simply they’re used 2-liter soda bottles. They’ve been filled with water along with two caps worth of bleach to keep microorganisms out. The cap is then covered with a film canister to protect it from the sun. They are installed through holes in the roof, and in full sun they put out the equivalent of a 50 watt incandescent light bulb.
This was done in Philippines. Water and bleach in bottle of coke was fitted on the roof. It reflects sunlight and is equal to 50 watt, a neat concept. I wonder if it would work on a bigger scale, like building the bulb the height of a
floor, or going down many sub levels.
2-Liter Bottle as a 50 Watt Light Bulb