As oil and gas prices continue to skyrocket, interest in renewable energy is starting to take center stage. One of the most abundant sources is solar power. However, solar panels have traditionally been expensive to mass-produce. Researchers at the University of California at Los Angeles (UCLA) have developed a more affordable way to harness the sun's rays by using solar cells made out of everyday plastics.
A team of engineers at the Henry Samueli School of Engineering and Applied Science led by professor Yang Yang recently unveiled an innovative polymer that can store solar energy. They believe it can be mass-produced at only 10 percent to 20 percent of the current cost of traditional cells, which would help make the technology more economically viable.
The price for silicon solar modules typically is around three to four times more expensive than fossil fuel. While prices have dropped since the early 1980s, the module itself still represents nearly half of the total installed cost of a traditional solar energy system.
Currently, nearly 90 percent of solar cells in the world are made from a refined, highly purified form of silicon-the same material used in manufacturing integrated circuits and computer chips. High demand from the computer industry has sharply reduced the availability of quality silicon, resulting in prohibitively high costs that rule out solar energy as an option for the average consumer.
The UCLA solar cell features a single layer of plastic sandwiched between two conductive electrodes. Yang claims that it is "easy to mass-produce and costs much less to make-roughly one-third of the cost of traditional silicon solar cell technology." The polymers used in its construction are commercially available in such large quantities that Yang hopes cost-conscious consumers worldwide will quickly adopt the technology.
"Solar energy is a clean alternative energy source," explains Yang. "It's clear, given the current energy crisis, that we need to embrace new sources of renewable energy that are good for our planet. I believe very strongly in using technology to provide affordable options that all consumers can put into practice."
Independent tests on the new solar cell already have received high marks. The National Renewable Energy Laboratory (NREL, Golden, CO) has helped the UCLA team ensure the accuracy of their findings. The efficiency of the cell is the percentage of energy the solar cell gathers from the total amount of energy, or sunshine, that actually hits it.
According to Yang, the 4.4 percent efficiency rating is the highest number yet published for plastic solar cells. "As in any research, achieving precise efficiency benchmarks is a critical step," he points out. "Particularly in this kind of research, where reported efficiency numbers can vary so widely, we're grateful to the NREL for assisting us in confirming the accuracy of our work."
Given the strides the team already has made with the technology, Yang believes they will be able to double the efficiency percentage in a short period of time. The target for polymer solar cell performance is ultimately about 15 percent to 20 percent efficiency, with a 15 to 20 year lifespan. Large-sized silicon modules with the same lifespan typically have a 14 percent to 18 percent efficiency rating.
However, the plastic solar cell is still a few years away from being commercially available. "We hope that, ultimately, solar energy can be extensively used in the commercial sector, as well as the private sector," says Yang.
"Imagine solar cells installed in cars to absorb solar energy to replace the traditional use of diesel and gas," adds Yang. "People will vie to park their cars on the top level of parking garages so their cars can be charged under sunlight. Using the same principle, cell phones can also be charged by solar energy. There are a wide variety of applications."