re: rather than re-invent the wheel...
Obviously using the water sprinkler seems the simplest, but the electromagnet system is interesting. And it could be something one could use in space solar panels- though the question is why isn't it already in use. I do seem to vaguely recall such an idea discussed for Mars rovers. Perhaps, it's power usage and it doesn't work as well as described.
I didn't notice any mention reclamation of the water used- and the recommendation of less periodic use in areas where water was scarce sort of confirms this isn't normally done.
And I suppose their "environmental friendly" solvent is ammonia [Windex]