The US National Renewable Energy Laboratory (NREL) has created thin film solar panels that are very close to competing with their more traditional silicon-based cousins. "The copper indium gallium diselenide (CIGS) thin-film solar cell recently reached 19.9 percent efficiency in testing at the lab, setting a new world record."
19.9% refers to how much of the sun's light is converted to electricity by the panel. Multicrystalline silicon-based solar cells have shown efficiencies as high as 20.3 percent (without concentrators...), so thin film is very close. Any fraction of a percent makes a big difference over the decades of useful life of a panel. :: NREL Sets Thin Film Record See also: ::Solaria: Finding Clever Ways to Make Cheaper Solar Panels, ::Hairy Solar Panels Could Result From Nanowire Breakthrough, ::Moth Eyes May Hold Secret to Better Solar Panels
Update: If you are interested in solar power, also check out 15 Photovoltaics Solar Power Innovations You Must See.