Making cheaper solar panels by making less waste

Researchers in Germany have developed a new technology that reduces solar costs substantially. 

|
Bruno Kelly/Reuters/File
Francisco da Silva Vale, 61, cleans solar panels which power ice machines at Vila Nova do Amana community in the Sustainable Development Reserve, in Amazonas state, Brazil, September 22, 2015.

Solar photovoltaics can generate clean electricity, but until recently one major barrier to greater adoption is the fact that solar panels have been prohibitively expensive.

In recent years there have been technological advances in photovoltaic cells’ efficiency, and increased production has brought down their cost. But they remain relatively expensive in large part because fully half of the costly silicon wafers at the heart of solar cells are destroyed during production.

Now researchers at the Fraunhofer Institute for Solar Energy Research (ISE) in Freiburg, Germany, have developed a technology that cuts these losses in half and, at the same time, reduces fabrication energy costs by 80 percent.

Making silicon wafers requires a lot of time and energy, and the silicon waste only adds to the expense. Silicon costs about $17 per kilogram, meaning that about $9 worth of silicon is wasted in making solar cells because the process ruins approximately half the silicon.

But the Fraunhofer researchers say they’ve solved both the waste and energy problems. “[W]e are reducing material losses by 50 percent while using 80 percent less energy,” said Stefan Janz, the lead ISE researcher on the project.

Until now, making a solar cell starts with impure silicon that’s liquefied, then purified with the addition of chlorine, creating a material known as chlorosilane. With the addition of hydrogen, chlorosilane becomes highly pure chunks of polysilicon.

To turn polysilicon into the crystals needed for solar cells, the chunks are broken, melted at temperatures exceeding 2,600 degrees Fahrenheit, then allowed to grow randomly, sometimes into amorphous and therefore useless silicon, and sometimes into the crystalline form suitable for photovoltaic cells. The usable polysilicon is then molded into huge ingots, then cut with saws into small wafers.

 

Both the high heat used to melt the polysilicon, the random growing of the material and the silicon dust from the sawing cause great waste of an expensive resource. But the ISE method addresses all three causes of the waste, Janz says. The Fraunhofer method heats the chlorosilane under lower heat, about 1,800 degrees Fahrenheit, then mixes it with hydrogen. Lower heat translates into lower cost.

Next, the silicon is vaporized and allowed to flow past a crystalline silicon wafer, which acts as a kind of template that orients the silicon vapor to eventually become crystalline itself. “We don’t let the silicon just grow randomly,” Janz said.

This process drastically reduces silicon waste. It’s also economical because the “template” wafer can be reused dozens of times. It also gives the wafers their final shape, eliminating the need for wasteful sawing.

“In this way we get a very good monocrystal, which is the best type of crystal, and the wafers are of the same quality as those produced using conventional methods,” Janz said.

Material loss isn’t the only disadvantage of sawing. Franunhofer says sawn wafers can’t be thinner than 150 to 200 micrometers or they’ll shatter during cutting. Under the new manufacturing method, the wafers can be half as thin. This material savings alone reduces the cost of a solar cell by 20 percent.

Fraunhofer’s ISE team has created an offshoot company called NexWafe, which is expected to begin using the new technique to mass producing the wafers in late 2017.

Source: http://oilprice.com/

Original article: http://oilprice.com/Latest-Energy-News/World-News/Latest-Innovation-Could-Be-A-Game-Changer-For-Solar-Cell-Manufacturing.html

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to Making cheaper solar panels by making less waste
Read this article in
https://www.csmonitor.com/Environment/Energy-Voices/2015/1015/Making-cheaper-solar-panels-by-making-less-waste
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe