Solar panels to produce electricity are one of the most well-known alternative energy technologies. You’ve seen solar cells deployed on parking meters, the occasional retail store rooftop, and maybe a neighbor’s house. Part of what prevents solar photovoltaic systems from being more widespread is cost—solar panels require a big upfront installation investment, and in an era of cheap coal and natural gas, the competition with conventional electricity generation is intense.
Most commercial photovoltaic solar cells use a semiconductor material to absorb solar radiation and produce electricity. For many conventional photovoltaic semiconductors, issues such as manufacturing and installation costs, materials scarcity, and/or toxicity could limit their widespread adoption. The Department of Energy’s Sunshot Initiative is aimed at making solar energy technologies cost-competitive with other forms of energy by reducing costs by about 75% by 2020. Berkeley Lab researchers are exploring all aspects of photovoltaic solar, including radically new basic science approaches to the underlying conversion of sunlight into electricity.
Questions we're answering
- Can we engineer a semiconductor material that can absorb almost all of the sun’s rays?
- Can we engineer semiconductor devices that achieve efficiencies far greater than the current state-of-the-art?
- How does solar energy policy affect electricity markets?
- What are the environmental, health, and economic impacts of large-scale solar-energy harvesting installations?
If solar cells could generate higher voltages when sunlight falls on them, they’d produce more electrical power more efficiently. For over half a century scientists have known that ferroelectrics, materials whose atomic structure allows them to have an overall electrical polarization, can develop very high photovoltages under illumination. No one had figured out exactly how this photovoltaic process occurs, until a team of researchers at Berkeley Lab and the University of California at Berkeley resolved the high-voltage mystery for one ferroelectric material and determined that the same principle should be at work in all similar materials.
Although full-spectrum solar cells have been made, none yet have been suitable for manufacture at a consumer-friendly price. Now Wladek Walukiewicz (pictured right, above), who leads the Solar Energy Materials Research Group in the Materials Sciences Division (MSD) at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), and his colleagues have demonstrated a solar cell that not only responds to virtually the entire solar spectrum, it can also readily be made using one of the semiconductor industry’s most common manufacturing techniques.
MSD’s Ali Javey and his research group have demonstrated a new way to fabricate low-cost, efficient, flexible solar cells for the conversion of light energy to electricity. The cells consist of arrays of optically active semiconductors arranged as nanoscale pillars on aluminum substrates. The inexpensive 3-D photovoltaic (PV) array can be designed to maximize both light absorption and conversion efficiency.
The installed cost of solar photovoltaic (PV) power systems in the United States fell substantially in 2010 and into the first half of 2011, according to the latest edition of an annual PV cost tracking report released by Berkeley Lab.
The Solar Energy Materials Research Group is developing novel materials that address the immediate need for sustainable, clean energy sources. They are currently investigating both Group III-nitride semiconductors as well as highly-mismatched alloys for a number of energy-generating applications.
Lawrence Berkeley National Laboratory works collaboratively with the US Department of Energy, state and federal policymakers, electricity suppliers, the renewable energy industry, academics, and others to conduct public interest research on renewable energy markets, policies, costs, benefits, and performance. Our work in these core areas focuses on renewable power generation, with an emphasis on wind and solar power. Much of this work is crosscutting in nature, however, and is applicable to a range of renewable energy technologies.
More than 30 years of experimentation was needed for the relatively simple thin-film silicon solar cell to reach its current efficiency of 24%. In order to develop next-generation solar cells based on new materials and nanoscience fast enough to reduce the global warming crisis, a different paradigm of research is essential. Exascale computing can change the way the research is done —both through a direct numerical material-by-design search and by enabling a better understanding of the fundamental processes in nanosystems that are critical for solar energy applications.