Subcontractor: Dr. Alex Cronin, University of Arizona

NREL Contract 99043, “Study Degradation Rates of Photovoltaic (PV) Modules Deployed in Arizona”

NREL Technical Monitor: Dr. Sarah Kurtz

Description: First Monthly Report

Author: Steve Pulver

Date: June 25, 2009

The data used for this study is expected to be collected from the Tucson Electric Power (TEP) solar yard. The majority of these modules were purchased between 2001 and 2003. There should be data from multiple years, from multiple types of modules.

Summary of what we are capable of measuring at the TEP solar yard:

A.  Types of modules and dates purchased:

PV Make / PV Model / SC Type / Inverter Make / Date Purchased
Sharp / NE-Q5E2U / px-Si / Aurora / Mar-2003
Kyocera / KC150G-A / px-Si / Xantrex / Apr-2003
BP Solar / BP 3150U / px-Si / Xantrex / May-2003
Uni-Solar / US-64 / MJ-Si / Fronius / Jun-2003
Sanyo / HIP-G751BA2 / HIT (Si)* / Sunnyboy / May-2003
BP Solar / MST50 MVHS / MJ-Si / Xantrex / Sep 2001?
Schott ASE / ASE-300-DGF/17 / px-Si / Xantrex / Jul-2001
BP Solar / SX140S / px-Si / Xantrex / 2002
Schott ASE / ASE-300-DGF/50 / px-Si / Xantrex / Aug-2001
Global Solar GSE / GG-112, 13309 / CIGS / Xantrex / 2002
Shell Solar / ST40 / CIS / Xantrex / Sep-2003
Sanyo / HIP-J54BA2 / HIT (Si)* / Fronius / Jul-2003
Shell Solar / SQ150-PC / x-Si / Xantrex / Sep-2003
BP Solar / MST50 MVHS / MJ-Si / Beacon / Feb-2004
BP Solar / MST50 MVHS / MJ-Si / Sharp / Sep 2003?
AstroPower / APi-165-MCB / x-Si (?) / Xantrex / May-2004
Solarex / MST-43MV / a-Si/a-SiGe / Solectria / Mar-2000
Evergreen / EC-115-GL / unknown / Soleil 2000 / Sep-2007
Schott ASE / 300-315 mixed / unknown / 3-phase / unknown
Global Solar GSE / Slim-Line 62W / CIGS / Xantrex / 2004
BP Solar / BP4170S / x-Si / Xantrex / Sep-2006

B.  Historical data:

Peak AC power output of the inverter, sampled at 15 min. intervals. This data should be going back to the time when the units were placed in operation. This information was collected by TEP, and we have been working with them over the last couple of weeks to get access to this data.

C.  Present data

Since the fall of 2008 additional measurements have begun; panel temperature, DC voltage, and DC current, all sampled at 1 second intervals

D.  Future data

Recently a weather station has been added. Data will now include Irradiance measurements, air temperature, wind speed, and wind direction sampled at 1 second intervals.

Recent work


I (Steve Pulver) have been working on the project since June 1, 2009. Most of the time has been spent working at the TEP solar yard, learning about the configuration of the hardware. In that time, the additional weather station has been added, and data collection has begun from this weather station. We will have a second, additional weather station in operation soon. Most of this work was done by other University of Arizona students including Daniel Cormode, Jason Veatch, and Kevin Pounds under the supervision of Dr. Alex Cronin from the University of Arizona and Mr. Bill Henry from Tucson Electric Power.

A. A Hall probe (for current measurement) has been added to the battery backup system of one inverter.

B. Attempted calibration of one DC voltage output of one of the units. There was a significant amount of noise in the measurement (with RMS values about the mean of 10% of the mean during a one minute period. We used smaller resistors in the voltage divider and this improved the signal to noise ratio.

C. First weather station was connected to an existing DAS box (Data Acquisition System) and a data logger was programmed to sample data from the weather station. An additional DAS box has been built for the second weather station and

Plans for the coming month

A.  verify calibration on our measurements: peak DC voltage and current, and panel temperature.

B.  Once we have access to the historical power output data, calculate total energy output by year.

C.  Find historical solar irradiance data that can be correlated with our TEP power data.

D.  A visit to NREL for Steve Pulver, Alex Cronin, and four other University of Arizona researchers has been planned for June 25 and 26.

Any questions can be directed to either Alex Cronin or myself, Steve Pulver.

Steve Pulver

520-294-6152 (Home)

Alex Cronin

520-465-8459 (Cell)