Researchers have designed a new solar power module that uses a curved mirror to focus sunlight onto a 5-inch glass ball that then spreads the light evenly across a solar panel, leading to twice the power output of traditional solar panels when combined with high-efficiency solar cells. The design was inspired by telescope technology and the high-efficiency solar cells used by space agencies.
The module also tracks the sun and rotates with it to increase its efficiency. The whole module is mounted on a steel 10-ft by 10-ft rotating frame that moves with the sun.
“The tracker is fully automated,” Blake Coughenour, a graduate student in the UA’s College of Optical Sciences, explained. “The system wakes itself up in the morning and turns to the East. It knows where the sun will rise even while it’s still below the horizon. It tracks the sun’s path during the day all the way to sunset, then parks itself for the night.”
One of the most interesting parts of the system is the mirror. The researchers came up with a dish-shaped mirror design that works very well for concentrating sunlight specifically for photovoltaics, as opposed to a solar thermal system.
“Most mirrors used in solar power plants are used for thermal generation by focusing light onto a long pipe used to heat water into steam. This requires the mirrors to be shaped like a cylinder. What we have learned here at the Mirror Lab is how to bend the glass to high accuracy so as to focus to a point or a line.”
The panels are created out of solar cells that are usually only used in spacecraft. These cells capture a wider range of the solar spectrum than regular cells. The ball lens is coated to maximize transparency for the suns rays. When put together with the mirrors, this system works very well to concentrate light on the the solar cells, but it also concentrates a bunch of heat. So the researchers designed a cooling system consisting of fans and a radiator that keeps the array within 36 degrees of the outdoor temperature.
Since the heat generated is itself a valuable resource the researchers are also “working on a way to use the mirrors to create an eco-friendly furnace that works like a toaster oven to burn a mold into a flat sheet of glass.”
From tests done by the researchers, a tracker featuring two mirrors generates enough energy to power two homes, but they hope to place eight mirrors on each module.
They say that “an array of sun trackers on an area measuring about seven by seven miles (11 x 11 km) would generate 10 GW of power during sunshine hours – as much as a big nuclear power plant. This technology has a lot going for it that makes it super promising.”
“Unlike conventional power plants that use steam to power turbines, Angel’s photovoltaic prototype uses no water, making it especially suitable for desert regions,” the University of Arizona reports. “The materials are cheap to produce and by concentrating sunlight with mirrors the plant’s footprint is smaller than that of PV panel-based plants.”
Source: University of Arizona
Image Credits: Blake Coughenour
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