[cornholio]

Focusing on pure energy efficiency might be missing the point of economic efficiency.

An RO desalination plant needs electric energy to drive the pumps, which might be generated by panels which are 15-20% efficient. So, if you can have cheap thermal desalination panels, they come out ahead even if 6x less energy eficient, you avoid the whole expensive and fragile desalination plant and you gain a low skill, distributed setup.

[ajb]

This is valid for some use cases, but then it needs to be compared with other solar distillation methods, of which there are already a variety at different levels of energy efficiency, complexity, and land use.