Geoffrey Wicks, PV Lab Manager and Application Scientist from MKS/Newport PV Calibration and Testing Laboratory, talks to AZoM about their Certification and Calibration Services
Please give a brief overview of the company and the work you do at MKS/Newport Photovoltaic Calibration and Testing Laboratory?
MKS Instruments, Inc. is a global provider of instruments, subsystems and process control solutions that measure, control, power, monitor and analyze critical parameters of advanced manufacturing processes to improve process performance and productivity.
Our products are derived from our core competencies in pressure measurement and control, materials delivery, gas composition analysis, control and information technology, power and reactive gas generation, vacuum technology, photonics, lasers, optics and motion control.
Our primary served markets are manufacturers of capital equipment for thin film including semiconductor devices, process manufacturing, environmental, life sciences and scientific research.
The PV laboratory provides third-party independent certification of PV device performance as well as calibration of reference PV cells.
The MKS/Newport PV Laboratory is accredited to the ISO/IEC 17025:2005 Standard by the American Association for Laboratory Accreditation (A2LA). What steps are required to maintain and improve this accreditation?
Accreditation to the ISO/IEC 17025:2005 International Standard (A2LA Scope #2893-01) is indicative of the attention to detail with which all laboratory activities are performed, and is the highest level of calibration laboratory accreditation.
Realization and preservation of this accreditation status requires the development, maintenance, adherence to, and continual improvement of a quality control system which ensures completion of the following main objectives:
- Traceability of all calibration results and corresponding uncertainty estimates to the International System of Units (SI) through National Metrology Institutes (e.g. NIST, NREL), as well as estimation of measurement uncertainty in accordance with the JCGM 100:2008 Guide to the expression of uncertainty in measurement Standard document or equivalent.
- Regular and scheduled participation in proficiency testing via inter-laboratory comparisons with other ISO/IEC 17025:2005 accredited laboratories, to ensure consistency of results from comparable labs and validate measurement uncertainty estimates.
- Standard operating procedures which are derived from and consistent with internationally-accepted standard methods of measurement and related specifications, as well as maintenance of training records which verify the competence of laboratory personnel to perform the methods.
- A controlled document system which allows for secure storage of critical laboratory documents, and ensures currency of work and calibration instructions in use.
- A controlled record system which ensures confidential storage of calibration and environmental records and also provides secure storage of laboratory purchasing, training, scheduling, audit, customer communication, and software validation records.
MKS/Newport Lab performs testing on PV samples for a wide range of applications. Please tell us more about this?
There is no question that the solar industry is expanding rapidly. Several relatively new (compared to Silicon) materials have been developed which have the potential to dramatically reduce production, manufacturing and installation costs, as well as to create new possibilities regarding installation locations (e.g. Building-Integrated PV, BIPV), while still providing comparable power conversion efficiencies.
In order to ensure consistent comparison of reported device performance parameters, international standards have been developed which clearly identify the conditions under which the performance determination should be made, and how the results should be reported.
There are many measurement and device subtleties which may affect the measurement results, peer-reviewed journals are increasingly requiring a third-party confirmation of performance results before accepting a manuscript for publication.
This is the basis for the demand for the certification of device performance. In order for a researcher to estimate their device performance and decide whether to publish the results, their internal measurement system must be calibrated using a reference PV cell.
This is the basis for the demand for calibration of PV reference cells.
Why is it important that third-party confirmation is carried out on test samples?
In order for the development and optimization of new PV materials to evolve efficiently, it is critical to have a set of calibration laboratories, whose measurement results have been demonstrated to be inter-consistent, which can provide independent and unbiased characterization of PV devices.
This data also provides researchers with the opportunity to both improve their materials and/or device design, as well as to compare their results with those provided by the calibration laboratory in order to provide an investigative tool for the enhancement of their measurement apparatus or procedures.
What sets MKS/Newport lab apart from other laboratories?
There are very few PV calibration laboratories in the world which are accredited to the ISO/IEC 17025:2005 Standard. This distinction is held with pride and with a high level of responsibility for the laboratory output.
The MKS/Newport PV Laboratory defines itself with integrity, meticulous procedural performance, accurate and efficient operation, as well as interactions with its customers which are based on mutual respect and a genuine concern for their requirements.
Please can you explain the technique and processes you follow when carrying out testing on a PV sample?
The procedures followed in the PV Lab are derived from and consistent with the ASTM E948 and E1021 standard methods and references therein, along with the associated standard specifications.
The procedures are also consistent with the ISO/IEC 60908 series of PV measurement methods.
What obstacles can you experience when carrying out quality control on a test sample?
Every research device is unique, in its mechanical design, electrical behavior and/or contacting architecture. The most common contributors to measurement uncertainty for these devices are aperture alignment, making efficient 4-wire contact without damaging the pads, and temperature monitoring/control.
A few other factors that need to be considered are the following:
- Hysteresis behavior needs to be either accounted for or determined to be insignificant, and for perovskite devices, a full hysteresis analysis needs to be performed and the results of this analysis and conditions under which the reported results were obtained need to be included in the certificate such that a reader can get a clear representation of these conditions.
- Different devices, even in the same material class, also may have different requirements. Some devices require irradiation under 1 SUN conditions (light soaking) in order to bring the performance into equilibrium, while others may degrade in time scales of seconds under illumination.
- Some cells are very sensitive to relative humidity and need to be purged with Nitrogen gas during the measurements to prevent oxidation and decay.
- The shading due to top contact pads on e.g. CZTS-type cells needs to be accounted for in the comparison between the short-circuit current density derived from the quantum efficiency measurement and that from the IV and area data. This comparison is an integral part of the validation of the results, so that it is important that it is performed correctly.
How do you report the results? What do you class as a success?
The ISO/IEC 17025:2005 Standard clearly specifies the general reporting requirements for calibration certificates from accredited labs. These requirements are adhered to strictly. Furthermore, the standard methods mentioned earlier include more specific language regarding the reporting of PV measurement data.
These suggestions are also included in the certificates. My primary metric of success is the degree to which I follow the laboratory quality system.
This quality system has been developed and improved in order to maximize customer satisfaction and the reliability of the laboratory measurement results.
If at the end of the day, I can honestly say that I did everything in my power to satisfy my customers while maintaining the integrity and scientific reputation of the laboratory, I say that’s a successful day.
What is in store for the future of the MKS/Newport PV Laboratory.
I hope to collaborate with NREL and NIST to further refine and expand the measurement procedures in the lab, in order to offer a wider variety of testing and calibration services to our research customers.
I am also interested in expanding to larger sub-module device testing and incorporating a small-scale environmental testing unit.
Where can our readers go to find out more?
For readers who would like more information about the MKS/Newport PV Laboratory, please email or call me directly at [email protected] and 406-556-2469 (Lab) or 406-556-2489 (Office).
About Geoffrey Wicks
I received my graduate degree in physics from Montana State University while performing research on nonlinear optical processes in organic and organometallic molecules in solution and polymer media. The specific focus was on developing an ultrafast nonlinear optical transmission instrument to obtain two-photon absorption (2PA) spectral data, and using this data to characterize local electric fields in the molecular environment. I am now applying my optical characterization experience to the management and operation of the MKS/Newport PV Calibration and Testing Laboratory in Bozeman, MT.
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