Solar Cell Defect Mystery Solved After Decades of Global Effort
June 5, 2019 | University of ManchesterEstimated reading time: 3 minutes
A team of scientists at The University of Manchester has solved a key flaw in solar panels after 40 years of research around the world.
Solar panels are among the most available system of generating energy through renewable sources due to their relative cost and consumer availability. However, the majority of solar cells only achieve 20% efficiency—for every kW of equivalent sunlight, about 200W of electrical power can be generated.
Now an international team of researchers have resolved a key fundamental issue of material defect which limits and degrades solar cell efficiency. The problem has been known about and studied for over 40 years, with over 270 research papers attributed to the issue with no solution.
The new research shows the first observation of a previously unknown material defect which limits silicon solar cell efficiency.
Prof Tony Peaker, who co-ordinated the research now published in the Journal of Applied Physics said: “Because of the environmental and financial impact solar panel ‘efficiency degradation’ has been the topic of much scientific and engineering interest in the last four decades. However, despite some of the best minds in the business working on it, the problem has steadfastly resisted resolution until now.”
“During the first hours of operation, after installation, a solar panel’s efficiency drops from 20% to about 18%. An absolute drop of 2% in efficiency may not seem like a big deal, but when you consider that these solar panels are now responsible for delivering a large and exponentially growing fraction of the world’s total energy needs, it’s a significant loss of electricity generating capacity.”
The energy cost of this shortfall across the world’s installed solar capacity measures in the 10’s of gigawatts, this is equivalent to more energy than is produced by the UK’s combined total of 15 nuclear power plants. The solar shortfall has to be therefore met by other less sustainable energy sources such as burning fossil fuels.
The multi-disciplinary experimental and theoretical approach employed by the researchers identified the mechanism responsible for Light Induced Degradation (LID). Combining a specialised electrical and optical technique, known as ‘deep-level transient spectroscopy’ (DLTS), the team have uncovered the existence of a material defect which initially lies dormant within the silicon use to manufacture the cells.
Because of the environmental and financial impact solar panel ‘efficiency degradation’ has been the topic of much scientific and engineering interest in the last four decades. However, despite some of the best minds in the business working on it, the problem has steadfastly resisted resolution until now.
The electronic charge within the bulk of the silicon solar cell is transformed under sunlight, part of its energy generating process. The team found that this transformation involves a highly effective 'trap' that prevents the flow of photo-generated charge carriers (electrons).
Dr Iain Crowe said: “This flow of electrons is what determines the size of the electrical current that a solar cell can deliver to a circuit, anything that impedes it effectively reduces the solar cell efficiency and amount of electrical power that can be generated for a given level of sunlight. We’ve proved the defect exists, it’s now an engineering fix that is needed.”
The industry standard technique used to determine the quality of the silicon material measures the 'lifetime' of charge carriers, which is longer in high quality material with fewer 'traps'. The researchers in Manchester lead by Prof Matthew Halsall found that their observations were strongly correlated with this charge carrier lifetime, which was reduced significantly after transformation of the defect under illumination. They also noted that the effect was reversible, the lifetime increased again when the material was heated in the dark, a process commonly used to remove the 'traps'.
Climate crisis debate has intensified in recent memory and the drive towards renewables has been seen as a key policy shift. While the UK recently broke its previous record for going two weeks without using coal-produced power the same month saw that atmospheric CO2 has surpassed the highest level in human history.
Suggested Items
Europlacer Presents New Range of iineo SMT Placement Machines.
05/01/2024 | EuroplacerFor more than 15 years, the Europlacer iineo placement machines have made their mark on the SMT industry with unique features and unrivalled flexibility. Today, Europlacer announces the launch of the second generation iineo.
Incap US Hosts Annual Food Drive
04/30/2024 | IncapIncap US recently concluded its annual food drive, a tradition aimed at supporting the Greater Washington County Food Bank. This year marked the fourth year of the initiative, and we couldn’t be prouder of the collective effort that was made to its success.
Scanfil Uses Employee Engagement Survey to Improve
04/30/2024 | ScanfilOnce a year Scanfil arranges Employee Engagement Survey (EES) in order to get valuable insight from its employees. In EES all employees are invited to share their opinion, bring ideas for improvements, and contribute to making Scanfil a better place to work.
epoxySet Introduces EO-20E – Versatile, Electrically Conductive Epoxy
04/29/2024 | epoxySetepoxySet produces EPOXIOHM EO-20E an industry established, reliable electrically conductive epoxy designed for solder replacement, chip bonding and other intricate electronic and optoelectronic assemblies. This creamy paste has a an easy to use 1:1 mix ratio with a 48 hour work time.
The Right Approach: I Hear the Train A Comin'
04/25/2024 | Steve Williams -- Column: The Right ApproachTraining is often an afterthought in many organizations, and the longer a company has been in business, the more this seems to apply. Over the past couple of decades, it has been amazing to observe that the biggest offenders of this are the companies that overuse the sound bite, “Our most important assets are our people.” When you dig into the process and peel back the onion, their commitment to training is not commensurate with that statement.