Fact 1: The primary ingredient of most solar panels is purified sand. Fact 2: Enough sunlight hits the Earth in an hour to provide all of humanity's energy needs for a year. So why isn't solar power cheap and abundant?

For starters, building a device capable of turning incoming photons into electricity isn't cheap. Add in installation and the cost of a solar system can still be more than $10 per watt of electricity produced. That's much higher than the cost per watt from burning coal or natural gas.

It's going to take further technological breakthroughs to make photovoltaics cheaper. That’s the conclusion of a report from Lux Research, a firm that advises emerging technologies.

New developments could include growing pure silicon wafers rather than sawing them from long ingots; or even fundamental shifts in the physics employed, like using so-called black silicon or quantum dots.

Of course, if all energy sources paid their full price, solar would be more competitive. After all, making solar panels doesn't result in nearly as much mercury, CO2 and other pollution as spewed by coal-fired power plants. If the health and environmental costs of coal or natural gas were included in their prices, suddenly solar might look a whole lot cheaper.

—David Biello

[The above text is a transcript of this podcast.]