Back in February I posted my nasa deep thought about why they didn't put blowers/wipers on the mars rovers… I got to ask one of the NASA scientists during a talk recently at Texas A&M, and then this morning I pull up CNN. There's an article about the rovers getting their lives extended. Then there it is, in paragraph 6:
Steve Squyres, the Mars rovers principal investigator, said the rovers' designers deemed the additional weight of adding wipers or blowers to the solar panels was not worthwhile. Instead they increased the size of the panels to maximize the power input.