Solar panels are nice in that if one fails, you just replace it. That's also why they are not nice; all the upsides and downsides of a disposable unit-based system.

I'm curious where you are getting this "conservative" estimate of 50 years. I typically hear 20 years, 40 years tops.

photovoltaics might be the future, but they aren't the today as best I can tell. They are inefficient, and much like the Prius batteries people like to talk about, are pretty environment-unfriendly to manufacture.