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SFAZ/ASTI Proposal: Cronin / Conant / Kostuk. Part I. Synopsis: TEP Solar Test Yard Research In collaboration with Tucson Electric Power (TEP), we will acquire and analyze data from the TEP solar test yard. Over 600 photovoltaic modules, from 20 different manufacturers are operating at the TEP solar test yard, with 23 inverters in strings similar to residential systems. This diverse set of PV hardware supplies 90 kWpeak to the grid. TEP will authorize this yard, with $1,000,000 of equipment, to be used by universities for research on the performance of PV systems. Many panels at the yard have been operating in the Tucson environment continuously since September 2003. Computerized data acquisition, facilitated by University of Arizona researchers, began in October 2008. With data from the TEP solar test yard we will answer the questions:
• How well do photovoltaic systems perform in the field ? • What are the temperature coefficients of efficiency for each type of panel ? • What is the annual, daily, and 1Hz energy yield of each PV system ? • How do PV modules and inverters perform compared to their specifications ? • How can we best forecast the annual PV energy yield for any given system ? • How do aerosols, winds, clouds, and other weather conditions affect PV systems ? • How can we predict the statistics of PV energy production at any given site ? • How well do various low-concentration-ratio PV systems perform ?
Professor Alex Cronin will establish continuous computer-controlled data logging capability at the TEP solar test yard. Students will install sensors for DC current, DC voltage and AC power produced by each string of panels. The temperature of each type of panel, the air temperature, wind velocity, direct and diffuse solar irradiation, and the spectral content of this irradiation will be measured at a 1 Hz rate. A fleet of data-logging computers will be interfaced with a data archiving and distribution networks. Professor Bill Conant will use this data, and a network of solar irradiation sensors, to refine a predictive model for photovoltaic energy yields that has, as its core, a state of the art Monte Carlo climate model. The impact of aerosols, wind, rain, direct and diffuse insolation, and clouds on the performance of PV systems will be reported. Professor Ray Kostuk will design and test new types of PV modules at the TEP solar test yard. New types of concentrator technology and bi-facial solar cells will be tested in field conditions of the TEP yard. Data from the solar test yard will then be used to refine better technologies for greater PV energy yield. This work will inform utility companies, homeowners, PV panel installers, and researchers about the performance of existing and new types of photovoltaic systems in the Arizona environment.
SFAZ/ASTI Proposal: Cronin / Conant / Kostuk. Part II. Project Description: TEP Solar Test Yard Research Many PV modules and inverters are available to study at the TEP solar test yard. A list of hardware is in Table I. A photograph of the yard is shown in Figure 1. The yard is 8 miles from the University of Arizona, as shown in the map in Figure 2. Table I. Photovoltaic hardware already operating at the TEP solar test yard. SYST. NO.
PV MODULE TYPE
POWER/ MOD.
NUMBER OF MOD.S
INVERTER TYPE
TOTAL POWER
1 Sharp 165 W 16 Aurora 2.64 kW 2 Kyocera 150 W 9 Xantrex TR 1.35 kW 3 BP 3150U 150 W 10 Xantrex TR 1.50 kW 4 Unisolar 64 W 24 Fronius 1.54 kW 5 Sanyo 167 W 8 Sunnyboy 1.34 kW 6 BP MST50 150 W 30 Xantrex TR 1.50 kW 7 ASE DGF17 300 W 6 Xantrex TR 1.80 kW 8 BP SX140 140 W 10 Xantrex TR 1.12 kW 9 ASE DGF50 300 W 6 Xantrex TR 1.80 kW 10 GSE 45 W 32 Xantrex TR 1.44 kW 11 Shell 40 W 38 Xantrex TR 1.52 kW 12 Sanyo 180 W 8 Fronius 1.44 kW 13 BPMST50 50 W 30 Sharp 1.50 kW 14 Solarex MST50 50 W 150 Beacon 7.50 kW 15 Shell 150 W 20 Xantrex TR 3.00 kW 16 Astro 164 W 9 Xantrex TR 1.48 kW 17 BP MST43 43 W 60 Solectra 2.58 kW 18 ASE DGF17 300 W 10 Xantrex OH4 3.00 kW 19 ASE DGF50 300 W 10 Xantrex OH3 3.00 kW 20 GSE 62 W 21 Xantrex TR 1.30 kW 21 BP 4170 170 W 10 Xantrex GT 1.70 kW 22 Kyocera 190 W 10 Fronius 1.90 kW 23 Sharp 300 W 128 3-phase 38.40 kW Total 19 Module Types 663 panels 11 Inverter Types 89 kW
Figure 1. The TEP solar test yard. The shade structure near the shed houses five inverters.
Figure 2. A Google Map, showing the TEP solar test yard and the University of Arizona.
Three professors: Cronin, Conant, and Kostuk, will collaborate to acquire and analyze data from the TEP solar test yard.
Dr. Alex Cronin, an Associate Professor at the University of Arizona Department of Physics and College of Optical Sciences will lead the data acquisition effort. Cronin is the lead author for this proposal.
Dr. Bill Conanant, an Assistant Professor at the University of Arizona
Department of Atmospheric Sciences, will analyze the impact of atmospheric conditions, and will refine energy yield models based on the TEP solar test yard data.
Dr. Ray Kostuk, a Full Professor at the University of Arizona Department
of Electrical Engineering and College of Optical Sciences, will lead research on new instrumentation and new tests of concentrator technologies at the TEP solar test yard.
This team is coordinated with the Arizona Research Institute for Solar Energy (AzRISE); and we will enlarge this team to collaborate with more professors from ASU and UofA. For example, we will share the data with anyone affiliated with TEP, ASU, or UofA, and we will incorporate new experiments to cross-calibrate and better utilize the TEP solar test yard. We will acquire and test new PV technologies with equipment provided by TEP and any other collaborating parties such as Prism Solar Technologies. The TEP solar test yard is ideally situated to answer the questions:
• How well do photovoltaic systems perform in the field ? • What are the temperature coefficients of efficiency for each type of panel ? • What is the annual, daily, and 1Hz energy yield of each PV system ? • How do PV modules and inverters perform compared to their specifications ? • How can we best forecast the annual PV energy yield from any given system ? • How do aerosols, winds, clouds, and other weather conditions affect PV systems ? • How can we predict the statistics of PV energy production at any given site ? • How well do various low-concentration-ratio PV systems perform ?
To answer these questions we will monitor the DC current and DC voltage from each string of PV modules with a 1 Hz sampling rate continuously throughout the year. We will also monitor the AC power that is delivered from each inverter to the grid. Four students and Professor Alex Cronin began work on October 28, 2008 to add instrumentation to the TEP solar test yard. Our first data are shown in Figure 3. Already we can tell that weather affects the performance of these panels in a non-trivial way. For example, the panels perform better on a windy day. Extensive correlation analyses will reveal the distinct impacts of wind, air temperature, and the spectral content of solar radiation.
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Sunny day air high: 25 C air low: 8 C
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Figure 3. Photovoltaic output measured on Nov 14 and 15, 2008. (A) DC voltage and current during two days for string #2 of 9 Kyocera solar panels. The Xantrex TR inverter regulates its input impedance to optimize the solar panel power output. This is known as “maximum power point tracking”. (B) The AC power output measured from the Aurora inverter (string #1). The power output was not the same on the two days, probably due to the different temperatures. (C) Panel temperature measured by a thermocouple attached to the back of a solar panel. Higher temperatures decrease the solar panel efficiency (see figure 6). It is interesting to note that the ambient temperature was the same on the two days, however, there was more wind on Nov. 15, making the panels cooler, and thus more effective. The AC power output of four different inverters is shown in figure 4. From these preliminary data we can tell that different inverters and different solar panel types perform quite differently near dawn and dusk. By optimizing the performance at low-light levels, it appears possible to obtain 10% more annual energy yield. More data from the TEP solar test yard will inform us how to obtain this enhanced energy yield.
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Kyocera / Xantrex (#2) Sanyo / Sunnyboy (#5)
Sharp / Aurora (#1)
Unisolar / Fronius (#4)
Figure 4. Different panel / inverter combinations have different turn-on behaviors. Understanding why they perform differently near dawn and dusk is an open question.
The DC voltage is monitored with a voltage divider. The DC current is monitored by a Hall probe. The AC power is monitored with a utility-grade AC current meter. Each signal is recorded with a microcontroller that is designed to run continuously all year round. Data will be available in real time on the internet from this system. Photos of the DC and AC sensors and the microcontrollers are shown in Figure 5.
Figure 5a: University of Arizona undergraduate Nick Davidson installing DC sensors at the TEP solar test yard at inverter #5.
Figure 5b: University of Arizona students Vincent Lonij and Ryan Price programming data-loggers at TEP by inverter #1.
Figure 5c. Dr. Cronin attaching sensors to microcontrollers at the TEP site.
Figure 5d. DC current and voltage monitor hardware. A box like this will support each PV string
The temperature of each type of panel, the air temperature, wind velocity, direct and diffuse solar irradiation, and the spectral content of this irradiation will be recorded by the microcontrollers too. A fleet of 22 data-logging microcontrollers will be programmed to communicate over Ethernet with a data-archiving web server. This will distribute the data to all the researchers involved. Results from a predictive model for the effect of irradiation on panel temperature and efficiency are shown in Figure 5. This model will be tested with data from the TEP yard.
Figure 6. A model for PV system performance on a windless, cloudless summer day.
Milestones for Year 1.
o Install DC and AC sensors, irradiation sensors, meteorological sensors, and microcontrollers on all 23 strings of panels / inverters.
o Calibrate, archive, and distribute data from all of these sensors.
o Establish continuous data logging.
Milestones for Year 2.
o Publish data on the performance of all 19 module types in the Arizona weather. Analyze and report the temperature coefficient of efficiency of all modules.
o Refine and publish models that predict the annual energy yield for each type of
PV installation.
o Install new PV hardware, including concentrating modules, at the TEP solar test yard.
Milestones for Year 3.
o Report the annual, monthly, and 1 Hz energy yield of various PV installations with novel concentrator technologies.
o Report statistical fluctuations of PV energy yields from year to year in Arizona.
o Report on aging characteristics and competitive advantages for PV system
components in the Arizona environment.
o Continue automatically acquiring and distributing data from the TEP solar test yard.
A letter indicating the commitment from Tucson Electric Power (TEP) for this partnership is presented next. It is noteworthy that in addition to the estimated $1,000,000 worth of existing hardware at the solar test yard, TEP will continue purchasing hardware for better measurements and new experiments.
The proposed budget from SFAZ/ASTI is $50,000 per year for each of 3 years. This funding will be used to support one graduate research associate and two undergraduate student employees each year, and to upgrade instrumentation for new research. The students will be supervised by Dr. Alex Cronin. The annual budget breakdown is: Graduate RA (before overhead) $35,000 Undergrads (20 hrs/wk @ $10/hr) $10,000 New instrumentation $ 5,000 _____________________________________ Total $50,000 Biographical sketches for professors Bill Conant and Alex Cronin are included as an appendix.
WILLIAM C. CONANT Assistant Professor
Department of Atmospheric Sciences University of Arizona
1118 E 4th St, Tucson AZ 85721-0081 (520) 626-0624, 621-6833 (fax)
a. Education and Training Ph.D. Oceanography (Physical) 2000 Scripps Institution of Oceanography, UCSD M.S. Oceanography (Physical) 1996 Scripps Institution of Oceanography, UCSD B.S. Physics (Earth Sciences) 1992 University of California, San Diego (UCSD) b. Research and Professional Experience 2005- Assistant Professor of Atmospheric Sciences, University of Arizona 2004-2005 Senior Postoctoral Scholar, Department of Environmental Engineering,
California Insitute of Technology (Caltech); (2001-2004) Postdoctoral Scholar, Department of Environmental Engineering, California Institute of Technology
2000-2001 Postdoctoral Researcher, Scripps Insitution of Oceanography, UCSD; (1993-2000) Graduate Student Researcher, Scripps Institution of Oceanography, UCSD; (1991-1993) Undergraduate Research Fellow, Scripps Institution of Oceanography, UCSD
c. Relevant Publications Conant W.C., J.H. Seinfeld, J. Wang, G.R. Carmichael, Y. Tang, P.J. Flatau, K.M.
Markowicz, and P.K. Quinn, 2003: A model for the radiative forcing during ACE-Asia derived from CIRPAS Twin Otter and R/V Ronald H. Brown data and comparison with observations, J. Geophys. Res., 108, art. no. 8661.
Conant W.C., A. Nenes, and J.H. Seinfeld, 2002: Black carbon radiative heating effects on cloud microphysics and implications for the aerosol indirect effect: 1. Extended Köhler theory, J. Geophys. Res., 107, art. no. 4604.
Conant W.C., 2000: An Observational Approach for Determining Aerosol Surface Radiative Forcing: Results from the First Field Phase of INDOEX. Journal of Geophysical Research, 105, 15347-15360.
Conant W.C., A.M. Vogelmann, and V. Ramanathan, 1998: The Unexplained Solar Absorption and Atmospheric Water Vapor: A Direct Test Using Clear-Sky Data. Tellus, 50B, 526-534.
Conant W.C., V. Ramanathan, F.P.J. Valero, and J. Meywerk, 1997: An Examination of the Clear-Sky Absorption over the Central Equatorial Pacific: Observations Versus Models. Journal of Climate, 10, 1874-1884.
Ramanathan, V., B. Subasilar, G.J. Zhang, W.C. Conant, R.D. Cess, J.T. Kiehl, H. Grassl, and L. Shi, Warm pool heat budget and shortwave cloud forcing: A missing physics?: 1995, Science, 267, 499-503.
ALEXANDER D. CRONIN Associate Professor: Department of Physics
Joint Appointment: College of Optical Sciences University of Arizona
1118 E 4th St, Tucson AZ 85721-0081 (520) 465-8459
a. Education and Training Ph.D. Physics 1999 University of Washington M.S. Physics 1995 University of Washington B.S. Physics 1993 Stanford University b. Research and Professional Experience 2008- Associate Professor of Physics, University of Arizona 2008- Consultant, Prism Solar Technologies 2002-2008 Assistant Professor of Physics, University of Arizona 1999-2002 Postoctoral Researcher, Massachusetts Institute of Technology (physics) 1998-1999 Product Inventor, Product Manager, Terabeam Corporation c. Honors 2008 Distinguished Early Career Teaching Award, College of Science, UofA. 2005 Outstanding Undergraduate Teaching Award, Department of Physics, UofA. d. Selected Publications Cronin, A.D., J. Schmiedmayer, and D.E. Pritchard, 2009: Optics and Interferometry
with Atoms and Molecules, Reviews of Modern Physics. ArXiv:0712.3703v1. McMorran, B. and A.D. Cronin, 2008: A Model for partial coherence and wavefront
curvature in grating interferometers, Phyical Review A 78, 013601. Jacquey, M., A.Miffre, M. Buchner, J. Vigue, and A.D. Cronin, 2008: Dispersion
compensation in atom interferometry by a Sagnac phase, Phys. Rev. A 78, 013638. Cronin, A.D., M. Bhattacharya, V.P.A. Lonij, and J.D. Perreault, 2008: Modifying atom-
surface interactions with optical fields, Physical Review A 77, 043406. Carr, A.V., Y.H. Sechrest, S. Waitukaitus, J. Perreault, V. Lonij, A.D. Cronin, 2007:
Cover slip external cavity diode laser, Reviews of Scientific Instruments 78, 106108. Cronin, A.D., 2006: Atom Interferometry on a Chip, Nature Physics, 2, pg. 665 Cronin, A.D. and B. McMorran, 2006: Electron interferometry with nano-gratings,
Physical Review A 74, 061602R. McMorran, B., Savas, T.A., A.D. Cronin, 2006: Diffraction of 0.5 kV electrons from
free standing transmission gratings, Ultramicroscopy 106, p. 356. Perreault, J.D., T.A. Savas and A.D. Cronin, 2005: Observation of atom wave phase
shifts induced by vdW atom-surface interactions, Physical Review Letters 95,133201. Uys, H., J.D. Perreault, and A.D. Cronin, 2005: Matter-wave decoherence due to a gas
environment in an atom interferometer, Physical Review Letters 95, 150403. Roberts, T.D., A.D. Cronin, M.V. Tiberg, and D.E. Pritchard, 2004: Dispersion
compensation for atom interferometry, Physical Review Letters 92 060405.
