Yes, the world still has a long way to go in terms of tapping into the tremendous energy resource of the sun.

And, yes, for those of us who are strong solar supporters in the United States, it's just plain pitiful and embarrassing that the U.S. trails much smaller countries such as Italy, Spain and Japan in terms of installed solar capacity, not to mention also smaller -- and far cloudier -- Germany, the global solar leader.

But the good news, as this infographic from REN21 (Renewable Energy Policy Network for the 21st Century) shows, is that solar is growing exponentially globally. And, by the way, 51 gigwatts of solar capacity is equal to approximately 46 nuclear power plants and about 100 typically sized coal power plants.

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