Download OREC Designs a Portable PV Array Instrument

OREC Designs a Portable PV Array Instrument
5 k Watt PV Array I-V Curve Tracer
Press Release from Oregon Renewable Energy Center
Klamath Falls, Oregon In January of
2005, the Oregon Renewable Energy
Center (OREC) completed field tests of
their prototype 5k Watt Solar Array
Current-Voltage Curve Tracer (IVCT).
February 22, 2005
Aaron McKay, OREC Research Assistant
and the Prototype 5 k Watt PV I-V Curve T
The instrument measures the current,
voltage and power output performance
of up to a 5 k Watt photovoltaic (PV)
array under actual field conditions.
The design parameters for the 5kWatt array unit
included: ability to test solar arrays in the field,
deployable by one person, ability to store multiple
test data sets, test solar arrays of up to 5kW in
desert temperatures (120 degrees F), test both
high voltage (600 Volts) grid connected string
arrays and high current (100 Amps) stand alone
arrays, and transmit stored data sets to a PC.
The instrument measures and stores the
voltage, current, power, solar radiation and
ambient temperature data taken during the
test. The project, under the supervision of
OREC Research Professor John Yarbrough, was
part of a series of PV I-V curve tracers designs undertaken by OREC. The project grew from a single PV cell IV curve tracer that was designed
to characterize individual solar cells to the 5 kWatt instrument. A second generation PV I-V curve tracer expanded the capability of the single
cell unit to capture I-V data of PV panels of up to 300 Watts. Oregon Institute of Technology senior students Ted Sahlstrom and Aaron McKay,
working for OREC as research assistants, were key participants in the instruments development.
Aaron McKay, OREC Research Assistant, continued with the project into the third generation. The major limitations of the two prior
instruments were low power handling capability and lack of field portability. The design parameters for the 5k Watt array unit includes: field
deployable by one person, ability to store multiple test data sets, test PV arrays of up to 5kW in desert temperatures (120 degrees F), test
both high voltage (600 Volt) grid-connected string arrays and high current (100 Amps) stand alone arrays, and transmit stored data sets to a
PC. The instrument has auto voltage and auto current ranging capability.
Where the previous generation instruments used a PC interfaced to a data aquisition card as a controller; the third generation unit used an
embedded microcontroller. The microcontroller stored I-V and power output, ambient temperature and solar radiation data to download to a
PC or laptop computer for creating graphic display.
The completed instrument met all of the design parameters.