Project data

Summary of the project

Photovoltaic generators are operated for several decades. The modules are covered by a linear performance guarantee from the manufacturers, who promise a module output of 90 per cent after ten years and 80 per cent of the original nominal output after 20 years. Depending on the system design and module technology, the system voltage of the photovoltaic generator can lead to potential-induced degradation (PID). This decrease in power cannot be detected by simple measurements using a multimeter in the open field. For a meaningful and reproducible analysis of the module parameters, a current-voltage characteristic curve must be recorded in the laboratory under standard test conditions (1000 W/m², 25 °C, AM1.5). An LED solar simulator is used for this purpose at Nordhausen University of Applied Sciences (Fig. 3). Internal damage to the modules, such as cell cracks and inactive cell areas, can only be visualised using special imaging techniques such as infrared thermography (Fig. 1) or electroluminescence (Fig. 2). Carrying out all these measurements in the laboratory requires the dismantling, transport and handling of all the individual modules, which incurs high costs and takes a lot of time.

The aim of the PV-FeldLab project is to create an overall concept according to which all these measurements can be carried out on large-scale systems directly on site in the field. The aim is to achieve the accuracy of laboratory measurements. By further developing the approaches for field measurements of individual modules given in IEC 61853, a method for measuring entire strings is being developed. Here, the self-referencing algorithm (SRA) co-developed by Coburg University of Applied Sciences is being further developed from its use with individual modules to its use with module strings.

The ageing behaviour of different module technologies varies greatly. At Nordhausen University of Applied Sciences, the ageing behaviour of different module technologies is analysed using accelerated ageing tests in the climate chamber (Fig. 4). The ageing parameters determined under laboratory conditions are transferred to an ageing model with the help of free-field measurement data. The results of the measurement campaign are used on the one hand to predict the service life and on the other to train the measurement concept for recognising degraded modules. In the course of the project, a variety of module technologies will be used to teach the measurement method in order to ensure reliable use of the measurement method on as many system types as possible.
(Editing Nordhausen University of Applied Sciences: Amélie Oberdorfer, Lukas Gerstenberg, Sebastian Voswinckel, Viktor Wesselak; Editing Coburg University of Applied Sciences: Bernd Hüttl, Samuel Schneider)

We would like to thank the German Federal Ministry of Education and Research (BMBF) for funding the "PV-FeldLab" project as part of the Research at Universities of Applied Sciences funding programme under the funding code FKZ 13FH600IB6 (2018-2022).