Making money with Solar panels

[FormulaTwo]

I have been reading a lot lately about solar panels.
It seems to be a fact that if you power your home off of them, any unused energy can go back into the grid. Where the energy company will actually pay you money for the energy you are generating.

My question, is this.....


If the electric company is giving you money to supply them with energy. What does this equal out to as in $ per kwh?

Would it be worth it, to put solar panels up, and just pump this into the grid to make money off of the electric company? Without using it for your home at all?

Lets say, if you lived near a river, and rigged up a large amount of hydroelectric generators, and fed that into the grid?

Or maybe, hook up a ton of wind generators, and feed those directly into the grid.

What if one were to buy an acre of land. Using these 3 technologies, all for the purpose of supplying clean energy, and making money off of the electric company at the same time?