If I were to guess as to the motivations of those who downvoted, it'd be because of this statement: > Just cover the canals as cheaply as possible. Covering t

If I were to guess as to the motivations of those who downvoted, it'd be because of this statement: > Just cover the canals as cheaply as possible. Covering the panels as cheaply as possible is probably not worth the cost. Covering the canals with something that produces energy tips the scales to make covering worth it. Then there's this part: > And then put solar panels where it makes sense to put them I agree with that, and wouldn't consider that worthy of a downvote. But without an explanation of "where it makes sense to put them", it's not very constructive. Your reply, however, is far more constructive. It probably doesn't makes sense to cover every possible square inch of canal without considering the costs and benefits, or without considering the costs and benefits of alternative solutions. Keep in mind, the idea isn't only to produce energy. It's about reducing evaporation and maintenance of uncovered canals. Covering panels with just about anything other than solar panels helps reduce evaporation and maintenance, but that's it. If you can cover it with something that can produce energy, then the cost of covering the canals can be offset by the energy produced. Emphasis on "can", because as you point out, it's not as simple as slapping panels down and calling it a day.