Weathering of PV Modules

This first book on durability studies of photovoltaic modules provides the background information on this hot topic, including operating conditions and stress factors. The experienced author team covers various accelerated life tests, including single stress-factor tests and combi-tests.
A must-have for the photovoltaic industry as well as researchers (material scientists, physicists and chemists) working in the field.

INTRODUCTION
Market needs and developments
Design of presently used and future PV-devices
Characterisation of PV-modules

OPERATION CONDITIONS
Weathering, voltages, soiling, salt impact

OUTDOOR MONITORING
Sensors for climate-measurements
Data-acquisition systems
IV-curve measurements

EVALUATION OF STRESS CONDITIONS
Correlation macro-climate and micro-climate
Modelling micro-climate: Module temperature, surface humidity, effective humidity
Comparison of the climate at different testing sites and evaluation of stress levels

ACCELERATION FACTORS AND TIME TRANSFORMATION FUNCTIONS
Acceleration possibilities
Acceleration models (time transformation functions) for the different stress factors

DEFINITION OF ACCELERATED LIFE TEST (ALT) CONDITIONS FOR DIFFERENT LOCATIONS AND DIFFERENT STRESS FACTORS
ALT for tropical, arid, urban, maritime and alpine conditions for UV-load, moisture, humidity, temperature difference, potential induced degradation etc.

SINGLE STRESS-FACTOR ALT
Requirements for the test equipment
Test results
Evaluation of the material-specific parameters for the time-transformation function

DESIGN OF COMBI-TESTS
Simultaneous stress application (UV and humidity, temperature cycling and humidity)
Modelling by FEM
Requirements to the test equipment
Sequential test procedures

EVALUATION OF COMBI-TESTS WITH DIFFERENT STRESS LEVELS
Service life estimation from combi-tests

OUTDOOR EXPOSURE
IV-curve monitoring and evaluation
Comparison with ALT

ANALYSIS OF DEGRADATION PRODUCTS
Non-destructive optical methods (spectroscopy, luminescence)
Destructive methods (Rheology, SEM/EDX)

PROPOSAL FOR ACCELERATED SERVICE LIFE TESTING PROCEDURE

MODELLING THE INTEGRAL ENERGY YIELD DURING THE LIFE-TIME
Degradation functions from combi-tests
Low-light-behaviour
Comparison of different modules and systems operating at different locations

Dr.-Ing. Michael Köhl, physicist, has been actively involved in the field of solar energy conversion since 1977. He presently works on service-life analysis of solar collectors and photovoltaic modules in the department Weathering and Reliability at Fraunhofer ISE. He was the coordinator of various successful EU projects on durability testing of solar energy systems, and leader of the German flagship project on durability of PV modules ?PV-Zuverlässigkeit?. Up till now he edited two textbooks on the durability of optical materials and on the potential of polymeric materials for solar thermal applications.

Sandrin Saile, M.A. joined Fraunhofer ISE's department "Weathering and Reliability" in 2009 where she is responsible for the management and dissemination of the department?s research activities. Another field of work is networking in international solar energy committees with a special interest in transdisciplinary sustainability studies and the interconnection between environmental politics, culture and technology.