CAMP December Newsletter: Page 4
Electroanalytical Characterization of Materials for Photovoltaic Applications
A solar cell, placed on a test-platform (equipped with a Peltier-module temperature controller), is being studied under illumination.
CAMP Professor Dipankar Roy and his group are using electroanalytical methods to characterize advanced/cost-effective materials for photovoltaic (PV) applications. Their experimental strategy is based on combining the techniques of potentiodynamic probing and impedance spectroscopy (IS) to simultaneously monitor the D.C. and A.C. electrical response characteristics of solar cells. This approach is capable of measuring a broad range of cell-parameters that often are not readily accessible with conventional D.C. techniques alone.
Current versus voltage characteristics of PV cells, obtained from potentiodynamic measurements, are used to determine fill-factors, D.C. resistances, open circuit voltages, short circuit currents, maximum-power points, as well as (with the incorporation of an adequate light source) energy conversion efficiencies. The D.C. cell resistance contains both series and parallel branches, which can be decoupled using IS. This information is useful for studying the ohmic power loss components in a PV cell. Impedance spectroscopy can also measure the different capacitive elements of solar cells (such as the depletion and diffusion capacitances for Si cells). This latter information is relevant for designing transient loads such as charge regulators for PV systems. The results obtained in this way for single PV cells can be "scaled-up" through computer simulation to analyze electrical characteristics of solar modules and arrays. The Clarkson group's current work involving PV materials focuses on two specific systems, namely dye-sensitized solar cells (supported by the ARO), and Si solar cells based on upgraded metallurgical grade Si (supported by DOE through TSEC). More information about this research can be found at http://people.clarkson.edu/~surop/PV test.htm.
Initial Testing of the Grid Electrostatic Precipitator
John Dunn (kneeling) adjusts the power supply to the GEP pre-charger unit (located on the right), while CAMP Professor John McLaughlin (standing) observes. Aluminum oxide particles are passed through the Plexiglas box into the pre-charger unit, and a Wide-Range Particle Spectrometer (not visible) is used to detect particle agglomeration.
Mr. John Dunn, Dr. Xinli Jia, and Professor John McLaughlin have begun preliminary tests of the pre-charger unit of a grid electrostatic precipitator (GEP) in a room provided by Professor Andrea Ferro (from Clarkson's Department of Civil and Environmental Engineering). The GEP pre-charger unit is shown in the accompanying photograph. The goals of the current tests are to (1) quantify the pre-charger's ability to agglomerate 0.2 micron aluminum oxide particles supplied by Ferro Corporation, and to (2) determine the success of a catalytic unit in removing ozone. Once these tests are completed and the pre-charger has been optimized, the full device will be tested at Clarkson. The GEP will then be moved to the Infotonics Technology Center where it will be tested in a cleanroom early next year. The goal of the project is to develop and commercialize a GEP that can be used as a replacement for HEPA filters. The large pressure drop across HEPA filters results in significant power consumption. For example, it costs the Infotonics Technology Center roughly one million dollars per year to provide the airflow to its cleanrooms, and much of this cost is due to the HEPA filters. The GEP will eliminate most of this cost. The project is being funded by Cameron Manufacturing & Design (Horseheads, NY) through a grant to Clarkson and by a matching grant from CAMP. Professor Goodarz Ahmadi is a Co-PI on the project and provides expertise on Corona discharge. Mr. Dunn is an inventor who is a consultant for Cameron Manufacturing and a Research Scientist at Clarkson University. Dr. Jia is a Post-Doctoral Research Associate at Clarkson.