Hacker News Reader

Veritasium's Derek Muller did an episode on this three years ago:

Wouldn't floating white spheres make more sense ? If the goal is to avoid overly warm mater.

White would reflect more, but also allow light to pass through. The goal of these are to completely block light to prevent algae growth.

Veritasium video about Los Angeles' reservoir black spheres project. They used black because

- The goal was light-blocking more than anything else; black worked best

- The black pigment held up to the environment (especially UV degradation) better than anything else they tried

I expect the second point was the most important thing. Black plastic is very stable.

Indeed - and it can help reduce evaporation, too. It's just that in some instances, some algae growth and some evaporation might be desirable.

No solar installation will block all of the light. Gaps between panels or rows may provide as much light as could be desired.

Note, most aquatic wildlife benefits from shade, even where they depend on an algae-rooted food chain.