Solar Cells Are Out of This World

Southface’s Kavin Manickaraj traveled to Cape Canaveral, Florida this past weekend to watch a NASA rocket launch to the International Space Station. Why is a Southface staffer going to see a rocket launch newsworthy? This rocket was carrying five thin-film solar cells that Kavin designed, destined for the International Space Station. The cells will remain at the station for between four and six months. Manickaraj was in graduate school at Georgia Tech when his research advisor, Jud Ready, came to him with a radical proposal and pending NASA grant to redesign solar cells. They began work in April of 2013 and concluded the project in August of 2014.

The cells aren’t your normal rooftop solar panels. They measure about one inch by one inch each, and are made of copper, zinc, tin and sulfur, materials that could withstand the cosmic radiation that bombards the International Space Station, and which we are safely insulated from by about 93 million miles and a comfy ozone layer. Normal solar cells are flat, which either reflect, absorb, or transmit light through the cell. Manickaraj and his team designed three-dimensional cells, with pockets allowing for a greater absorption of light, called light trapping. Solar cells that go into space normally are made of gallium arsenide, but Manickaraj’s cells swapped these high-efficiency elements for copper, zinc, tin and sulfur. “So, ours are different because they replace some of the rarer elements,” Manickaraj says. “We don’t use any gallium, we don’t use any arsenic, so it’s cheaper materials for theoretically similar performance.”Launch Screen Grab400

After nearly two years of delays, Manickaraj’s cells finally took flight, and SpaceX held a reception to view and celebrate. “It was super energetic,” Manickaraj says. “The entire launch and landing lasted about ten minutes, but there was a reception beforehand, and the launch was at about 12:45 am. Starting at about 11:00 pm, there was this gathering with beer, food and presentations. And everyone was just buzzing. Right around 12:15, 12:30 am, people are going out to the parking lot to watch the launch itself … We’re all waiting around, and finally when it launched—my brother and my mom have never seen a launch before—they instantly became ten-year-olds. It was almost embarrassing, how excited they were watching this happen. I could feel the launch in my chest; it’s loud; it’s by no means a quiet endeavor, it’s very, very loud and very, very bright.”

Now that the cells are in space, their ability to minimize reflection and increase absorption will be monitored via a few sensors which will measure “the current coming off the cells, the total amount of power these cells are producing, and the temperature of the cells,” Manickaraj says. “There’s also a sensor that tells you how much light is hitting the surface. So, the reason we’re doing it in space in this instance is because it’s actually going to be outside of the International Space Station where there’s no radiation shielding, so you get to see what the effects of radiation are on the cell itself.”

Kavin and his brother resizeIt will be at least a few weeks before Manickaraj’s cells transmit data back to Earth, and there are a few different variables, such as temperature swings expanding and contracting the metal or the vibrations from the rocket launch, influencing how much data will be available during the 16 sunrises and sunsets per day experienced by the International Space Station. “I don’t really know what to expect,” says Manickaraj. “I’m trying to not make any claims as of yet, I’d rather sort of be surprised by what we get.”

Manickaraj and the team he worked with will continue to monitor the results alongside NASA. He says “this was basically phase one of what I think is going to be a pretty long study for the research group.” As for Manickaraj, he says, “it feels weird. I guess I got used to [the cells] being around, and not really going up, but when the day finally came, it was like reaching a milestone. I’m following the news as much as possible, because I can’t wait for some of the numbers to come back.”


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