Energy Major

Well, there are technical colleges that have solar technician programs, but that may not be what you're looking for.

There are many engineering degrees that could help you. Environmental engineering may help, but there is also nuclear engineering (nuclear power), electrical engineering, and civil engineering. Electrical engineering will probably bring up some stuff about renewable energy sources, that might be your best bet.

However you could do renewable energy work in other fields. Don't limit yourself. If you know what you want to do, that's great. I want to go into Aerospace Engineering, and there's plenty of environmental problems there that can be solved. But Electrical Engineering would probably be what you want to go for. Also you could do your own research for renewable energy sources. I've heard there are grants for students wanting to do their own research projects.