Cleaning is certainly a key issue as can be seen in this article: https://www.nature.com/articles/s41893-020-0553-2?draft=collection https://www.nature.com/art

Cleaning is certainly a key issue as can be seen in this article: https://www.nature.com/articles/s41893-020-0553-2?draft=collection https://www.nature.com/articles/s41893-020-0553-2?draft=coll... However, there are a few complexities. Cleaning the panels continuously also causes the panels to degrade quicker. Robots for each string of panels is also a significant capital investment. Imagine an installation with hundreds of string of panels and robots for each one. In most cases panels are cleaned by human teams and not on a continual basis.