There’s a new solar panel design that is hoping to yield solar power at 5 cents per kilowatt-hour, which makes it equivalent to coal:

Sunrgi Exits Stealth, Promises to be as Cheap as Coal

From the article:

Sunrgi’s technology is fairly simple. Basically they use a magnifying glass to concentrate the power of the sun 1600 times onto a tiny square of the most efficient photovoltaic material on the planet. While others are concentrating on bringing the price of the panels down (along with efficiency), Sunrgi actually uses panels from Spectrolab, which are three times more efficient than the cheap panels being produced by NanoSolar.

Here’s a demonstration: