2Introduction 5
2 Introduction
The devices of type PVPM enables the measurement of the I-V-curve of photovoltaic modules as well as of
strings. By a new developed procedure the device can measure and calculate the peak power Ppk, the Rs and
Rp directly at the place of installation of the PV system. Calculation results and the diagram can be displayed on
the internal LC-display.
The peak power is the power of a module under Standard Test Conditions (STC) [1]. In the past the very
complex measurement of the peak power was possible only in particularly suited laboratories. By a new
patented method [2], which was developed by Professor Wagner at the University of Applied Sciences
Dortmund, this measurement can easily be performed with the PVPM. So the quality control of a PV system can
be executed fast and economically. This simple and meaningful check in practice serves the certainty of the
customer and also that of the installer. Beyond that the measured I-V-curves permit further explanations about
the electrical characteristics of the checked module or string. So the PVPM is suitable as an instrument in
research as well as for development purposes.
The PVPM is a mobile measuring device with integrated battery supply and battery charger in a durable metal
housing. The device has its own industrial miniature PC and a high-contrast LC display and thus its function is
independent of other devices. Nevertheless (if desired) a PC can be attached for data transfer and further
analysis of the measured values over a standard serial interface.
The PVPM is operated comfortably over a few keys and an on-screen menu. The functions are defined self-
describing and the user is always led by the program. So no long training activities for the operating personnel
are necessary.
The PVPM automatically measures the I-V-characteristic of the PV generator at a capacitive load. From the
measured data it calculates the effective solar cell characteristic, Ppk and Rs [2], [3]. After the measurement the
data are stored automatically in a non-volatile storage and so are available later (e. g. in the office) [4]. The
device internally can store the data of several 1000 measurements.
The following results are displayed:
Permanent values:
Peak Power P
Pk
Internal Series Resistance R
s
Internal Parallel Resistance R
p
Current values, depending on irradiation and temperature:
V
pmax
, I
pmax
, P
max
V
oc
, I
sc
, FF, T
mod
, E
eff
The determined I-V-characteristic can also be shown directly on the LC-display.
[1] IEC60904-3: STC= Irradiance 1000 W/m2, Spectrum AM=1.5, Cell Temper. 25°C
[2] Wagner A.: Peak Power and Internal Series Resistance Measurement under Natural Ambient Conditions. –EuroSun Copenhagen
2000
[3] Bendel C., Wagner A.: Photovoltaic Measurement relevant to the Energy Yield. - WCPEC3 Osaka 2003
[4] Schulte K.M., Wagner A.: Die Effektive Solarzellenkennlinie. - Anwendung Teillast-Berechnung. Staffelstein. 2002
3 Normal use
The peak power and I-V-characteristic measuring instrument series PVPM is used exclusively for the
admission of the I-V-characteristic curve of single photovoltaic modules and strings. Before connecting
the PV generator under test to the measuring instrument it must be ensured that the test specimen
cannot exceed the maximum current and voltage levels of the measuring instrument at any time.
Operation manual for PVPM devices PV-Engineering GmbH
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