At present, although the cost of solar energy has been greatly reduced with the continuous updating of technology, it is still more expensive than fossil energy. In addition, despite the solar panels "blooming everywhere" and even oversupply, the solar panel manufacturing industry is still at a low ebb. However, although the momentum of innovation in the solar energy market has weakened, there is still a lot of research progress "successfully". Overall, people in the industry are still optimistic about the long-term development of the solar industry.
Manufacturing flexible solar cells on glass
Traditional solar cells still focus on crystalline silicon technology. A few years ago, the cost of silicon solar panels was $ 4 / watt. Professor Martin Green, one of the "leading big brothers" in this research area, University of New South Wales, Australia, once declared that the cost of silicon solar panels can never be less than $ 1 / watt. But now, he said: "The cost has dropped to about 50 cents / watt, and it may be reduced to 36 cents / watt."
The goal set by the US Department of Energy is less than 1 cent per watt by 2020. This goal does not only refer to the cost of solar panels, but also in terms of the entire solar panel installation system. Green believes that it is possible for the solar industry to accomplish this goal in advance. By then, the direct cost of solar energy is expected to fall to 6 cents / kWh, which is lower than the energy supply cost of new natural gas power plants. The total cost of solar energy is of course higher due to the cost of facilities made up to compensate for the intermittent characteristics of sunlight, but the exact amount depends on factors such as how much solar energy is in the grid.
Various organizations in the silicon solar industry have been trying to cut costs and increase the energy output of solar panels. In the 1990s, Green's laboratory produced a solar cell with a record conversion rate, and its record has been firmly maintained to this day. In order to obtain this conversion record, Green had to use expensive lithography technology to make fine wires to collect the current provided by the solar cells. But the steady development of technology has allowed scientists to now make fine wires using screen printing. Recent research has shown that screen printing can produce wires with a width of only 30 microns, which is about the same width as Green's wire, but at a much lower cost.
Green said that the combination of this technology and Other technologies is expected to enable people to copy his high-efficiency solar cells on the production line more cheaply and more conveniently. An existing company has developed the technology to manufacture the metal contacts on the front of the solar cell. However, the design of the electronic contacts on the back end is more difficult, but he hopes that the company can come up with a way.
Coincidentally, the National Renewable Energy Laboratory (NREL) has created a flexible solar cell on a new type of glass (ultra-thin highly curved glass manufactured by Corning Incorporated). The thin-film cadmium telluride solar cell they made is currently the only solar cell that can compete with traditional silicon solar cells in mass production. At present, such solar cells can only be manufactured in batches (the same is true for silicon solar cells), but the ability to manufacture them on a piece of bendable glass offers the possibility that roll-to-roll can be used continuously Manufacture it in the same way (just like printing a newspaper), so you can reduce costs by increasing output.
"Two-sided baby girl" makes the sun nowhere to escape
Green's former student and colleague Zhao Jianhua is also the co-founder of China Solar Energy, a Chinese solar panel manufacturer. Zhao Jianhua announced last week that he is building an experimental production line for a "double-sided solar" cell that can absorb sunlight on both sides. The basic idea of ​​this solar cell is that during most of the day, the sunlight falling between the rows of solar panels on the ground is reflected to the back of the solar panels, and these lights are expected to be absorbed and utilized, thereby increasing energy production. Out. This study is especially applicable to desert areas, because the sunlight is very reflective. Single-sided solar panels can generate 340 watts of electricity; double-sided solar panels are expected to reach 400 watts. Zhao Jianhua hopes that these solar panels can increase the energy output by 20% within a year.
Such solar panels may be installed vertically like a fence, so that one side of the solar panel absorbs sunlight in the morning; the other side absorbs sunlight in the afternoon, which makes it possible to install this solar panel on the projectile ground For example, they can be used as noise barriers on highways. Moreover, the advantages of this layout strategy are expected to be demonstrated in dusty places. Many places in the Middle East seem to be the ideal destination for such solar panels, because despite the particularly strong sunshine in these places, frequent sand and dust storms will shrink energy output. Vertically installed solar panels will not provide a "safe place" for dust, so it is expected to make the entire solar system more economical and feasible.
Semiconductor "mate" may double the efficiency of silicon solar cells
However, from a longer-term perspective, Green still put his bet on silicon. He hopes to greatly improve the efficiency of silicon solar panels by allowing silicon to be "married" with two other semiconductors. Each type of semiconductor added to it will selectively absorb some of the light in the solar spectrum (silicon cannot effectively absorb this part of the light) and convert it into electrical energy.
Adding a semiconductor is expected to increase the photovoltaic conversion efficiency of solar panels from the current 20% to 25% to about 40%. Adding another kind of semiconductor is expected to make the efficiency as high as 50%, which can install at least half of the solar panels. Of course, the main challenge of this method is to make these semiconductors "marry" well. This challenge is mainly caused by the arrangement of silicon atoms in crystalline silicon.
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