With new technology close to the green plant's photosynthesis it's now possible to make solar cells less expensive.
Earth receives more solar energy in one hour than the entire planet currently consumes in a year.
Based on the principle of photosynthesis -- the biochemical process by which plants convert light energy into carbohydrate (sugar, their food) -- the Graetzel solar cell is composed of a porous layer of nanoparticles of a white pigment, titanium dioxide, covered with a molecular dye that absorbs sunlight, like the chlorophyll in green leaves. The pigment-coated titanium dioxide is immersed in an electrolyte solution, and a platinum based catalyst completes the package.
From Science Daily 12 th of April; Inexpensive Highly Efficient Solar Cells Possible
[tip from technology-will-save-the-world Jimmy, who might be right in this case]