|
Thursday, March 27, 2008 More-Powerful Solar CellsA new solar cell is 27 percent more efficient without being more expensive to make. By Kevin Bullis
An MIT researcher has found a way to significantly improve the efficiently of an important type of silicon solar cells while keeping costs about the same. The technology is being commercialized by a startup in Lexington, MA, called 1366 Technologies, which today announced its first round of funding. Venture capitalists invested $12.4 million in the company. 1366 Technologies claims that it improves the efficiency--a measure of the electricity generated from a given amount of light--of multicrystalline silicon solar cells by 27 percent compared with conventional ones. The company's efficiency and cost claims are based on results from small solar cells (about two centimeters across) made in the lab of Emanuel Sachs, a professor of mechanical engineering at MIT, who is one of the company's founders. 1366 Technologies is building a pilot-scale manufacturing plant that will make full-sized solar cells (about 15 centimeters across). Within a year, the company will decide whether its pilot-plant results justify building a factory for commercial production, Sachs says. Commercial solar cells made from multicrystalline silicon are normally far less efficient than more expensive ones made from single-crystal silicon, but they're cheaper. The 27 percent improvement will bring multicrystalline cells to efficiencies about the same as single-crystal cells--around 19.5 percent--at the lower costs. So, if the technology successfully scales up, Sachs says, it could significantly bring down the cost of solar electricity. Sachs says that today, solar cells cost about $2.10 per watt generated. When manufactured at a commercial scale, the first cells incorporating his new technology will cost $1.65 per watt. Planned improvements will bring down this cost to about $1.30 a watt, he says. To compete with coal, the cost will need to come down to about $1 a watt, something that Sachs predicts can be achieved by 2012 with further improvements in antireflection coatings and other anticipated advances. The company's first prototype solar cells include three key innovations to improve efficiency. The first is a method for adding texture to the surface of the cells that allows the silicon to absorb more light, a trick that's been used before with single-crystalline devices but has been difficult to implement with multicrystalline silicon. The rough surface causes light to bend as it enters the cell so that when it encounters the back of the cell, it doesn't reflect right back out; rather, it bounces off at a low angle and remains inside the slab of silicon. The longer the light remains within the silicon, the greater the chance that it will be absorbed and converted into electricity. |
Audio »
Share »
Digg this
Add to del.icio.us
Add to Reddit
Add to Facebook
Slashdot It!
Stumble It!
Add to Newsvine
Add to Connotea
Add to CiteUlike
Add to Furl
Googlize this
Add to Rojo
Add to MyWeb
Favorite
Print
E-mail
Toward Cheaper, Robust Solar Cells
03/13/2008
Comments
rttedrow on 03/27/2008 at 6:02 AM
30
Kevin Bullis on 03/27/2008 at 9:15 AM
Nanotechnology and Materials Science Editor
39
jmaximus9 on 03/27/2008 at 12:02 PM
32
simonseah on 05/05/2008 at 12:00 PM
1
Siphon on 03/28/2008 at 9:11 AM
93
Even easier: placing a mirror behind the panels to boost performance a bit, if the configuration allows it of course (eg a flat roof would work fine).
But the limits of conventional flat plate silicon based solar cells are in sight. They use a lot of material and the manufacturing plants are capital intensive. Roll-to-roll manufacturing of thin films carries far lower capital costs, so more production capacity can come on-line with similar investments. Then, more money can be earned quicker, so that even more production capacity can be brought on-line. You can see where this is going; factories with low capital costs can scale quicker, and do a lot more with less materials.
A major breakthrough would be to combine these advantages with the high efficiency advantage of flat plates. Up and down conversion could help, but what's really needed is exploiting nano-effects and possibly different materials.
Amorphous diamond, for example, could replace silicon as a semiconductor, allowing over 50% conversion efficiency while being more stable to cosmic rays than amorphous silicon thinfilms but with a similar potential for cheap roll-to-roll mass manufacturing.
High efficiency is important, as it can (ceteris paribus) reduce the installation costs, structural support costs, maintenance costs etc. which are significant when all combined.
Unless the initial cost targets can be brought to market really fast, they may find it too high a cost target compared with various competing technologies. We may have to be a bit more ambitious.
mattgroom on 05/08/2008 at 8:47 AM
1
I might have misunderstood the science but this is mine to date.
Lets say 100 photons pass through a film that has a transfer effiency of 4%, this to me means 4% of the lights energy from e=mc2 equation is turned to useable energy. This tells me that an enormous amount of light is needed to make a little energy.
So isnt it better to have something with 1% efficiency that lasts "forever" and can be layered to take 100% of the energy over time?
Eg a parabolic shape focuses light to an area, and mirrors can be layered such that no light emerges, and harnessed with gravity, aka blackholes that let no light out the light say could be made to have a 100% efficiency transfer from a 1% absorbing/tranfering material.
I say forget efficiency and collect all the light let it bounce around indeffinately being collected. Light can pass through itself so eventually you would have masses of light bouncing around indeffinately being transfered at such a huge rate it would be amazing.
Thats my 2 and half twisted cents.
Motto is dont lose the light.
timprosser on 05/23/2008 at 9:53 AM
1