The manufacture of solar panels is not as safe or as environmentally friendly as you might hope, just like how buying a new Prius to replace your car is probably a net loss for the environment unless your existing one is already near the end of its useful life.
You have to look at the whole market. When you buy a new car the old one gets resold to someone else, which causes yet another even older car to be resold and so on through the market until the oldest, broken-est car actually exits the market (assuming the total market size is static, if it's growing then you need to compare the Prius against the other new cars that would enter the market) so as long as you're replacing existing usage then you're probably doing good.
Yes, that's what I'm afraid of. Building solar cells might not be as environment friendly as I'd like, but hey, we can optimize these processes later on.
Building a nuclear plant would also be very unfriendly when it comes to ecology.
