Here is something I found to be absolutely fabulous. I use this SOLAR FAN in my greenhouse. I tilt the solar panel upward and of course in the greenhouse it gets sun from all sides. It is healthy for the plants to have air circulation, so it comes on when the sun comes out. I found this online and ordered it.
I think it is going to be exciting to see how technology progresses and more and more solar and wind powered things are developed. It saves you money and it saves the environment.