MIT Opens New Windows for Solar Energy

The Massachusetts Institute of Technology (MIT) recently reported a couple of developments that may help solar power enter the mainstream market. In one project, MIT reported new photovoltaic cells could be placed on windows without inhibiting views or light passage. The work involves the creation of a “solar concentrator.” In another project, MIT researchers have found a new way to store solar energy for when the sun isn’t available.

The first project showcased using windows as a solar collector.

“Light is collected over a large area [such as a window] and gathered or concentrated at the edges,” said Marc A. Baldo, project lead at MIT and associate professor of electrical engineering. According to Baldo, the focused light increases the electrical power obtained from each solar cell by a factor of more than 40.

Because the system is simple to manufacture, the team said it could be implemented within three years—even added onto existing solar-panel systems to increase efficiency by up to 50 percent. That, in turn, would substantially reduce the cost of solar electricity.

The MIT solar concentrator involves a mixture of two or more dyes that are essentially painted onto a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is re-emitted at a different wavelength and transported across the pane to waiting solar cells at the edges.

In the 1970s, similar solar concentrators were developed by impregnating dyes in plastic. But the idea was abandoned because not enough of the collected light could reach the edges of the concentrator.

“We made it so the light can travel a much longer distance,” said Jon Mapel, a graduate student in the Department of Electrical Engineering and Computer Science and researcher on the project. “We were able to substantially reduce light transport losses, resulting in a tenfold increase in the amount of power converted by the solar cells.”

In another MIT development, researchers have overcome a major barrier to large-scale solar power: storing energy for use when the sun doesn’t shine. Requiring nothing but abundant, non-toxic natural materials, this discovery could reinforce solar power’s entrance into the market.

Inspired by the photosynthesis performed by plants, Daniel Nocera, a professor of energy at MIT, and Matthew Kanan, a postdoctoral fellow in Nocera’s lab, have developed a process that will allow the sun’s energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating electricity for use anytime.

The new catalyst works at room temperature, in neutral pH water, and it’s easy to set up, Nocera said.

James Barber, a leader in the study of photosynthesis and professor of biochemistry at Imperial College, London, called the discovery by Nocera and Kanan a “giant leap” toward generating clean, carbon-free energy on a massive scale.

“This is a major discovery with enormous implications for the future prosperity of humankind,” Barber said.

Nocera hopes that, within 10 years, homeowners will be able to power their homes in daylight through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electricity--by-wire from a central source could be a thing of the past, he said.

In both cases, there seems to be a big push in academia for solar development, and these are just two projects that make solar power more feasible and affordable.

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