The idea isn't limited to reducing evaporation, but for controlling algae. From the article: > reduce algae growth and the need for maintenance by limiting sun

The idea isn't limited to reducing evaporation, but for controlling algae. From the article: > reduce algae growth and the need for maintenance by limiting sunlight falling on the water Evaporation is an issue, for sure, but so is the cost of keeping algae under control. It makes a lot of sense to trade algae for solar panels even if you have to maintain the solar panels.