1 Introduction
1-1
1
Introduction
Overview
The PVA-600 PV Analyzer is a portable test instrument designed to measure the current-
voltage (I-V) curves of PV modules and strings and immediately compare the results to
on-board PV model predictions. Measurement results are easily saved for future reference
and analysis.
The current-voltage (I-V) curve of a PV module, string, or array provides a detailed
description of its energy collecting ability. The curve ranges from the short circuit current
(Isc) at zero volts, to the open circuit voltage (Voc) at zero current. At the ‗knee‘ of a
normal I-V curve are the maximum power current and voltage (Imp, Vmp), the point at
which the array generates maximum electrical power. All of these important voltages and
currents are captured when the I-V curve is measured. The detailed shape of the curve
between these points gives additional information about the health of the PV module,
string, or array under test.
The value of a measured I-V curve is greatly increased when it can be compared with a
predicted I-V curve derived from an accurate PV model. Models take into account the
specifications of the PV modules, the number of modules in series and strings in parallel,
and the losses in system wiring. Other data used by the models include the irradiance in
the plane of the array, the module temperature, and array orientation.
