ENERGY SPECIAL...How solar cells can be 20 times more powerful

A team of researchers from MIT has discovered that photovoltaic cells become more efficient when they are built into towers, rather than lying flat on the roof of your house

Intensive research around the world has focused on improving the performance of solar photovoltaic cells and bringing down their cost. But little attention has been paid to the best ways of arranging those cells, which are typically placed flat on a rooftop, or sometimes attached to motorised structures that keep the cells pointed at the sun.
Now, a team of researchers from Massachusetts Institute of Technology (MIT) have come up with a very different approach: building cubes or towers that extend the solar cells upward in 3D configurations. Amazingly, the results from the structures they’ve tested show power output ranging from double to more than 20 times that of fixed flat panels with the same base area.
The biggest boosts in power were seen in the situations where improvements are most needed: in locations far from the equator, in winter months and on cloudier days. The findings are published in Energy and Environmental Science.
“I think this concept could become an important part of the future of photovoltaics,” says senior author, Jeffrey Grossman a professor at MIT.
The MIT team initially used a computer algorithm to explore an enormous variety of possible configurations, and developed analytic software that can test any given configuration under a whole range of latitudes, seasons and weather. Then, to confirm their model’s predictions, they built and tested three different arrangements of solar cells on the roof of an MIT lab building.
While the cost of a given amount of energy generated by such 3D modules exceeds that of ordinary flat panels, the expense is balanced by a much higher energy output for a given footprint, as well as much more uniform power output over the course a day, seasons, and in cloudy weather. These make output more predictable, which could make integration with the power grid easier than with conventional systems.

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