Wednesday, 14 December 2011 10:24
December 14, 2011
A novel manufacturing technique could help solar cell efficiency, making the renewable energy source more cost competitive with fossil fuels.
Companies that manufacture solar panels currently use a process through which silicon wafers are heated to temperatures higher than 1,000 degrees Celsius. Reaching such searing temperatures requires a significant amount of energy, which is counterintuitive given the benefits associated with the alternative energy technology.
Experts assert that in order for the clean technology sector to achieve an increasingly bigger market share over the coming decades, it is necessary that scientists improve current production techniques. Industrial engineering research taking place at the National Renewable Energy Laboratory in Golden, Colorado, aims to achieve such a goal, and scientists from the facility said recently they had crafted a new manufacturing process that uses significantly less energy.
In fact, scientists from the National Renewable Energy Lab asserted that by heating solar wafers through concentrated light beams, they had reduced energy consumption levels by roughly 50 percent during the production process. What's more, by employing light instead of heat during manufacturing, the researchers affirmed they were also able to remove impurities from the silicon wafers, potentially augmenting their power output.
The lab's novel manufacturing technology, dubbed the Optical Cavity Furnace (OCF), is still in the early stages of development, but scientists said initial results have been incredibly promising. By utilizing photonics, the OCF uses "tightly controlled engineering to maximize efficiency while minimizing heating and cooling costs," according to the scientists. Moreover, they asserted it is capable of purifying "solar cells at unmatched precision."
The design of the machine differs from that of conventional heating systems, according to MIT's Technology Review. The OCF is composed of an assortment of lamps that are contained within a highly reflective compartment, a design that allows the system to maintain a uniform temperature. The uniformity in temperature is so consistent, according to lab engineers, that it essentially prevents any energy from escaping.
"It virtually eliminates energy loss by lining the cavity walls with super-insulating and highly reflective ceramics, and by using a complex optimal geometric design," the scientists said. "The cavity design uses about half the energy of a conventional thermal furnace because in the OCF the wafer itself absorbs what would otherwise be energy loss. Like a microwave oven, the OCF dissipates energy only on the target, not on the container."
The researchers are also confident they can continue to tweak the design of the OCF, effecting efficiency improvements. National Renewable Energy Lab principal engineer Bushan Sopori asserted that lab scientists are poised to augment the device's efficiency by four percentage points. Such an uptick is significant, as efficiency improvements within the solar technology sector do not often surpass one half of a percentage point.
"Our calculations show that some material that is at 16 percent efficiency now is capable of reaching 20 percent if we take advantage of these photonic effects," Sopori said. "That's huge."
The OCF could also be used to introduce an oxidation step into the solar wafer manufacturing process. Under normal circumstances, oxidation is introduced only in the production of high-end solar cells, but the OCF would effectively make the process less expensive, enabling a larger number of firms to incorporate it into their production facilities.
With many of the government-funded tax incentives and subsidies supporting the clean technology sector set to expire over the next year, the researchers affirmed improving the OCF and other solar manufacturing technologies is essential to ensuring the future success of the industry.
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