In 4/2011, according to
Wikipedia, the total global electric power consumption is 15 TW, (15,000,000,000,000 watts). The potential available solar power is 86,000 TW. That's almost 6000 times more than we, the people of Earth currently need. The available wind power is 870 TW and the available hydroelectric power is 7.2 TW.
According to Technology Futurist
Ray Kurzweil, (in 2010) the total amount of solar energy being produced every year is doubling every 2 years. In 8 more doublings, he says that solar power could generate enough energy to supply all our energy needs.
Not to say that he's right or that this will happen, but the stage is being set for a great paradigm shift in the way we power our homes, our cars and for that matter, world economies.
Solar power alone cannot provide all the world's energy needs. We still need something that works at night and when it's cloudy.
The Eventual world wide renewable energy solution will be solar and wind power with hydroelectric acting as the regulator and battery back up for it all.
There are currently 60 planned or operational
pumped-storage hydroelectric stations
larger than 1 GW world wide. These work by pumping water to an upper reservoir during times of excess energy production and releasing it to the lower reservoir during peak demand. While most of these utilize conventional power plants to pump the water, solar and wind power is the next logical step.