文档介绍：Better Solar Energy Systems:More Heat,More Light
Solar photovoltaic thermal energy systems, or PVTs, generate both heat and electricity, but until now they haven’t been very good at the heat-generating pared to a stand-alone solar thermal collector. That’s because they operate at low temperatures to cool crystalline silicon solar cells, which lets the silicon generate more electricity but isn’t a very efficient way to gather heat.
That’s an economics problem. Good solar hot-water systems can harvest much more energy than a solar-electric system at a substantially lower cost. And it’s also a real estate problem: photovoltaic cells can take up all the space on the roof, leaving little room for thermal applications.
In a pair of studies, Joshua Pearce, an associate professor of materials science and engineering, has devised a solution in the form of a better PVT made with a different kind of silicon. His research collaborators are Kunal Girotra from ThinSilicon in California and Michael Pathak and Stephen Harrison from Queen’s University, Canada.
Most solar panels are made with crystalline silicon, but you can also make solar cells out of amorphous silicon, commonly known as thin-film silicon. They don’t create as much electricity, but they are lighter, flexible, and cheaper. And, because they require much less silicon, they have a greener footprint. Unfortunately, thin-film silicon solar cells are vulnerable to some bad-news physics in the form of the Staebler-Wronski effect.
“That means that their efficiency drops when you expose them to light—pretty much the worst possible effect for a solar cell,” Pearce explains, which is one of the reasons thin-film solar panels make up only a small fraction of the market.
However, Pearce and his team found a way to engineer around the Staebler-Wronski effect by incorporating thin-film silicon in a new type of don’t have to cool down thin-film silicon to make it work. In fact, Pearce’s group discovered that by