The company can produce solar cells for about 40 cents per watt
Twin Creeks Technologies—a startup that has been operating in secret until today—has developed a way to make thin wafers of crystalline silicon that it says could cut the cost of making silicon solar cells in half. It has demonstrated the technology in a small, 25-megawatt-per-year solar-cell factory it built in Senatobia, Mississippi.
Siva Sivaram, the CEO of Twin Creeks, says the company’s technology both reduces the amount of silicon needed and the cost of the manufacturing equipment. He claims the company can produce solar cells for about 40 cents per watt, which compares to roughly 80 cents for the cheapest solar cells now. Twin Creeks has raised $93 million in venture capital, plus loans from the state of Mississippi and other sources that it used to build its solar factory.
The conventional way to make the crystalline silicon wafers—which account for the bulk of solar cells—involves cutting blocks or cylinders of silicon into 200-micrometer-thick wafers, a process that turns about half of the silicon into waste. The industry uses 200-micrometer wafers because wafers much thinner than that are brittle and tend to break on the manufacturing line. But in theory, they could be as thin as 20 to 30 micrometers and still be just as efficient, or more efficient, at converting sunlight into electricity.
“Our cell can produce as much as twice as much power than conventional solar cells.”
Solar3D, Inc., the developer of a breakthrough 3-dimensional solar cell technology to maximize the conversion of sunlight into electricity, today announced a design modification that enables its super-efficient solar cell to collect sunlight from a wider angle than conventional solar cells. A patent application has been filed on the new design element.
“This major breakthrough combined with our record-setting high efficiency design can result in a solar cell that can produce 200% of the power of conventional silicon solar cells,” said Jim Nelson, President and CEO of Solar3D. “Conventional solar cells become dramatically less efficient if the sun is not shining within a narrow range of incident angles. Sunlight that hits the cell outside of this range will be reflected off, and the reduced solar energy causes the cell’s internal efficiency to drop. Because of a unique wide-angle design, our solar cell can maintain its high efficiency over a wider range of incident angles. It can capture more light in the morning and evening hours, as well as in the winter months when the sun is not directly overhead.”
The key to this breakthrough is a special design on the cell surface that collects sunlight over a wide range of angles. The collected light is then forced into 3-dimensional photovoltaic micro-structures beneath the cell surface that trap the light and convert it into electricity. As the sun moves across the sky, throughout the day or year, the Solar3D cell will be able to maintain its high conversion efficiency, as if the sun was directly above it.
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It is cheap to make and can be produced in large quantities
A team of researchers from the University of Notre Dame in Indiana is reporting the creation of a “solar paint” that could mark an important milestone on the road to widespread implementation of renewable energy technology. Although the new material is still a long way off the conversion efficiencies of commercial silicon solar cells, the researchers say it is cheap to make and can be produced in large quantities.
In an effort to find an alternative to silicon-based solar cells, the Notre Dame researchers turned to quantum dot materials. They started with nanoparticles of titanium dioxide (TiO2) and coated them with either cadmium sulfide or cadmium selenide – both compounds that can absorb photons. A photon of the right energy hitting the cadmium compounds causes an electron to escape, which is absorbed by the TiO2.
The resultant particles were then suspended in a water-alcohol mixture to create a paste. The cadmium sulfide mixture produced a yellow paste, while the cadmium selenide mix produced a dark brown. The most efficient was a mixture of the two that produced a light brown paste.
When the paste was brushed onto a transparent conducting material and exposed to light, it created electricity. To replenish the electrons lost by the cadmium and test the conversion efficiency of the paint-on electrode, cathodes made from other materials and additional compounds were used.
A new twist on an old solar cell design sends light ricocheting through layers of microscopic spheres, increasing its electricity-generating potential by 26 percent.
By engineering alternating layers of nanometer and micrometer particles, a team of engineers from the University of Minnesota has improved the efficiency of a type of solar cell by as much as 26 percent. These cells, known as dye-sensitized solar cells (DSSC), are made of titanium dioxide (TiO2), a photosensitive material that is less expensive than the more traditional silicon solar cells, which are rapidly approaching the theoretical limit of their efficiency. Current DSSC designs, however, are only about 10 percent efficient.
One reason for this low efficiency is that light from the infrared portion of the spectrum is not easily absorbed in the solar cell. The new layered design, as described in the AIP’s Journal of Renewable and Sustainable Energy, increases the path of the light through the solar cell and converts more of the electromagnetic spectrum into electricity. The cells consist of micrometer-scale spheres with nanometer pores sandwiched between layers of nanoscale particles. The spheres, which are made of TiO2, act like tightly packed bumpers on a pinball machine, causing photons to bounce around before eventually making their way through the cell.
A study in the journal Nature Materials details the creation of a nanowire-based technology that absorbs solar energy at comparable levels to currently available systems while using only 1 percent of the silicon material needed to capture photons.
Imagine a world where sunlight can be captured to produce electricity anywhere, on any surface. The makers of thin-film flexible solar cells imagine that world too. But a big problem has been the amount of silicon needed to harvest a little sunshine.
Now, researchers [led by Harry A. Atwater] at Caltech say they’ve designed a device* that gets comparable solar absorption while using just one percent of the silicon per unit area that current solar cells need. The work was published in the journal Nature Materials.