your link says they can just clean them once a week. that's a solved problem:

http://www.ecoppia.com/technology/

https://us.sunpower.com/blog/2017/12/04/meet-sunpowers-new-s...

or you can use a $100k panel washing truck: https://wash-bots.com/wp-content/uploads/2016/07/product2.jp...

A $100k expense and a person to drive it around cannot be a reasonable roadblock to solar, when we're talking about 100s of millions of dollars for one solar plant.