Streamlining the development of solar panel foil systems
07 November 2016
As a technology consultant, Dr. Peter Waegli works with a wide range of companies to bring the latest and most efficient technology to his clients.
His firm, Dr. P. Waegli-Research, provides technology-based strategies and solutions. He has used mathematical simulation in a wide variety of applications, such as fibre optical pressure sensors, MEMS flow sensors, vacuum sensors, measuring systems for optical coatings, fibre optical switches for safety applications, medical imaging modalities, and many more. Maple is a trusted tool for Dr. Waegli in his technology development solutions.
Dr. Waegli recently advocated the use of Maple in a project related to solar panels. Solar panels are composed of a collection of connected photovoltaic cells, and the type of cell interconnection technology affects the performance of the solar panel. Eppstein Technologies, a subsidiary of EppsteinFOILS, is a developer of innovative foil systems for interconnecting and encapsulating photovoltaic cells. In a recent project with Eppstein Technologies, Dr. Waegli used Maple and MapleNet to help the company streamline the development process of the foil systems.
In developing new products, the company has to meet specific customer requirements and qualify the performance in actual models. Therefore, the company builds test modules of up to six photovoltaic cells for its foil systems. These test modules then undergo the required module life cycle tests according to standard regulations. These tests verify that the performance of modules built with the company’s foil systems meets the industry’s quality standards as well as the specific, usually more stringent, specifications requested by the customers.
To streamline the testing process, Eppstein Technologies, in cooperation with Dr P. Waegli-Research, decided to build a module tester which illuminates the test modules to measure their power conversion performance. The module tester had to be cost efficient, easy to handle, adaptable to the size of the test modules, and allow for comparative characterisation of the modules with respect to the quality parameters influenced by the foil system, i.e. series resistance, shunt resistance and fill factor. It was decided that an LED-illumination was best suited to meet the design goals.
A simulation model for such a light source was built in Maple. This model simulates the light distribution and intensity for various arrangements and specifications of the LED sources. These results were then used to optimise LED positions, properties of the LEDs, and the collimation optics and distance of the LED assembly from the measuring plane. The Maple model also took into account the illumination spectrum and the spectral response of the photovoltaic cells to adjust the illumination, such that the cells produced an output that is equivalent to the one produced by an illumination of 1000W/m², as required by standards. Based on the results of this optimisation during the modeling phase, the tester light source was built and performed correctly on the first try.
Maple was also used to create a simulation model of the module itself. By illuminating the test modules with this LED light source, the current vs. voltage (I-V) curve of the photovoltaic module under test is measured. The Maple model contains an algorithm that reads the measured I-V data points and fits them with the simulated I-V function describing the photo response of the module. Based on the optimum fit found with Maple, the engineers could determine the module’s quality by extracting the values for series resistance, shunt resistance, and the fill factor. With virtual models of both the modules and the test platform, the company is able to optimise its designs early in the process, reducing the number of expensive physical prototypes they need to create and test.
The simulation model and the results were fully described in interactive Maple documents and shared using MapleNet, a solution that lets users add mathematical computations and visualisations to their web and desktop applications and share solutions over the web through interactive Maple documents. As a result, every design engineer on the project has access to the information and can run simulations with their own parameters online.
Dr. Waegli feels that Maple has significant advantages, it is much easier to use compared to other, similar products. Its intuitive user interface makes it simple to manipulate parameters, and it has good compatibility with other tools. In addition, its document interface is very useful as it provides ample opportunities to document work.
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