Build Solar Water Heater

I can’t afford solar panels; but I can, for example, afford to open my blinds during the day.
Do you know of any creative ways of harvesting the sun’s energy?

When i say renewable energy i mean like solar power, wind power, hydroelectric power . Is there a certain type of engineer who works in these areas? Where is a good place to go to school for this type of Engineering.

The more, the better. The arguments should be at least remotely feasible. I’m looking for ecological arguments why Solar Energy is a better alternative than Nuclear Reactors.