20 June 2012
Earlier this spring, we reported on a breakthrough in building-integrated photovoltaics (BIPV): a virtually ‘invisible’ conductive wiring system that transports electricity on glass windows, developed by New Energy Technologies, Inc. at the US Department of Energy’s National Renewable Energy Laboratory (NREL). Now the partners announced an improvement in its manufacturing technique that should lead to higher speed, lower costs and greater durability for the coatings.
According to the United States Department of Energy (DOE), there are over half a million square feet of windows in commercial and residential structures combined in the United States, presenting a huge opportunity to generate solar energy through those windows. New Energy Technologies is still working on its SolarWindow technology, an organic spray-on coating that allows see-through windows to generate electricity from sunlight. Making use of the world’s smallest functional solar cells, the coatings not only work in direct sunlight, but can also generate electricity under artificial light.
New Energy Technologies’ improved manufacturing process uses low-cost materials and a special application technique that could help optimize the movement of electrons within the ultra-thin solar cells. This should increase the amount of electricity produced when the SolarWindow prototype is exposed to natural or artificial light. This recent improvement means that the technology can be executed at ambient pressure and low temperatures, allowing researchers to avoid the use of materials that otherwise have to be deposited using high temperature vacuum deposition. Vacuum deposition is both expensive and time-consuming and, thus, not practical for high-speed and large-scale applications. The new process enables high-speed roll-to-roll (R2R) and sheet-to-sheet (S2S) manufacturing, which would be crucial for the commercialization of electricity-generating coatings on see-through glass and plastic.
“Over the past few months, our researchers have unveiled a virtually invisible conductive wiring system, which collects and transports electricity on SolarWindow prototypes, and have fabricated a large area working module, which is more than 14-times larger than previous organic photovoltaic devices fabricated at NREL,” says John A. Conklin, President and CEO of New Energy Technologies. “Earlier, we developed our first-ever working SolarWindow prototype using a faster, rapid scale-up process for applying solution-based coatings. Together, these achievements have moved us closer to our manufacturing, scale-up, durability, and power production goals - all important factors to advancing our SolarWindow technology towards commercial launch,” Conklin added.
To generate electricity on SolarWindow prototypes, researchers layer and arrange unique, ultra-thin see-through solar cells onto glass. Each of these cells is arranged in a network and interconnected by way of a virtually invisible grid-like wiring system. Within these ultra-thin solar cells, the light-induced movement of electrons generates electricity. When SolarWindow prototypes are exposed to light, the light’s energy prompts electron movement through specific physical and chemical mechanisms leading to power generation.
Dr. Scott R. Hammond, Principal Scientist at New Energy Technologies, Inc., believes this newest discovery could also favorably improve durability and shelf life of future SolarWindow products. “NREL scientists have previously published unrelated results that demonstrate dramatic improvements to the operational and shelf life of unprotected (non-encapsulated) photovoltaic devices utilizing related materials when subjected to continuous illumination. No doubt, this is a promising and significant advancement.”
Written by Sandra Henderson, Research Editor, Solar Novus Today
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