While the next big thing in solar is thin film material that can printed on roofs and fabrics, the "next next" thing might be windows that double as energy producers.

Octillion Corporation of Vancouver, BC, says it is developing nanosilicon photovoltaic solar cell technology that can be sprayed on windows and allow 70 percent of the light to pass.

The company is working with researchers at the University of Illinois in Urbana-Champaign to develop the technology, but they are still exploring the cost and energy efficiency potential of the material.

Konarka is also reportedly applying its thin film manufacturing to colored windows. Along with smart windows that darken to reduce the amount of UV light that passes through, the office buildings of the future may require considerably less electricity than today.

While much of the debate about our ability to produce sustainable electricity has been focused on the placement of solar panels and wind farms on open spaces, thin film solar can turn our developed real estate into a real energy solution.