Silicon Valley is coincidentally a place where home-time and solar-peak kind of coincide. My brother's solar panels peak in the late afternoon all summer, when he's programmed the air conditioning to come on.
As European I wonder if you really need a/c in Silicon Valley? I've never been there but from weather averages it seems that the climate is comparable with Paris where a/c's are absolutely not common. Even in more southern cities like Barcelona many people don't use a/c.
If you want to get very technical it is questionable whether or not you really need air conditioning anywhere. It's a luxury item and if you view it as such it's not surprising that people in SV have it - it's already a super high CoL place, might as well install some extra perks.