Verfahren zur Stabilisierung der Konversionseffizienz von Siliziumsolarzellen

Die vorliegende Erfindung betrifft ein Verfahren zur Stabilisierung der Konversionseffizienz von Siliziumsolarzellen, bei dem ohne Beleuchtung der Solarzellen eine externe elektrische Spannung an die elektrischen Kontakte der Solarzellen angelegt wird, um Ladungsträger in das Siliziumsubstrat zu injizieren. Die Solarzellen werden dabei auf eine Temperatur oberhalb einer Mindesttemperatur erhitzt und für einen Haltezeitraum oberhalb dieser Mindesttemperatur gehalten, während die externe elektrische Spannung an den Solarzellen anliegt. Das Verfahren zeichnet sich dadurch aus, dass die Stromstärke eines durch die angelegte elektrische Spannung in den Solarzellen fließenden Stroms und die Temperatur der Solarzellen nach Ablauf des Haltezeitraums in einer Abkühlphase jeweils so aufeinander abgestimmt reduziert werden, dass während dieser Abkühlphase bei jeder Temperatur eine möglichst hohe Konzentration an neutralem Wasserstoff im Siliziumsubstrat erhalten wird. Mit dem vorgeschlagenen Verfahren lässt sich die Konversionseffizienz von Solarzellen in einem sehr kurzen Behandlungsprozess stabilisieren, ohne hierdurch eine Reduzierung der Konversionseffizienz gegenüber einer Behandlung bei geringeren Temperaturen zu verursachen

A simulation based optical and electrical approach to estimate energy yield of various designs of curved modules

The concept of sustainable structures is tightly involved with the architectural designs. Photovoltaic is the cheapest way to generate small amount of electricity anywhere. When PV follows functional or aesthetic designs, curved shapes can become desirable. PV modules with curved shapes can follow different forms over the structures and generate electrical power. In this paper, we have simulated the radiation power over 60-cell modules with different angle of curvature by considering the location and the elevation of the modules. In the next step, we have simulated two different module interconnection layouts to investigate the performance of each module at specific levels of curvature. We show that after a range of curvature, it is better to use parallel coupled strings and change the interconnection of the modules to reduce current mismatch over the strings. In this study, we show that for the modules with the 8 degrees tilt angle between the cells, it is better to use standard series connected cells. For higher levels of curvature it is necessary to rearrange the interconnections. The module with parallel connected strings does not have bypass diodes and it can save up to 125% energy compared to the conventional one in high levels of curvature

Verfahren zur Prüfung der Anfälligkeit für potentialinduzierte Degradation bei Komponenten von Solarmodulen

The method involves applying and pressing a polymer film (16) on a semiconductor body (15) with a dielectric layer using a punch (7) with a metallic contact surface to form a stack of layers. The layer stack is brought to a test temperature and held for a test period at the test temperature. Electrical voltage is applied between the surface of the punch and a metal support (3) over the test period in a continuous or repeated manner. Potential-induced degradation of the determined semiconductor body with the dielectric layer is measured at the end or after the end of test period. An independent claim is also included for a device for testing susceptibility to potential-induced degradation of components of solar modules

Comparison of Optical Gains and Electrical Losses in Modules with Different Designs of Partial Cells in Desert Regions

Modules with partial cells have shown better performance compared to full-cell modules due to reduced electrical losses and increased optical gains. In this paper, we have compared different module concepts of full-cell, half-cell and third-cell with different tab widths of 0.8 mm and 1.5 mm in moderate and desert conditions. First, we present the statistical evaluation of indoor measurements results of the modules. The modules were measured with a mask which limits the spacing of the cells and keeps the total inactive area of the mini-modules constant. The efficiency and fill factor of the modules are evaluated to analyze the electrical and optical losses of the modules. We show that the modules with partial cells show better fill factor and efficiency compared to the similar full-cell modules. The modules were measured under different irradiation levels to evaluate the performance of the modules under different light conditions. Based on the measured data, the energy yields of the modules are simulated in Morocco and Germany as desert and moderate climates. We show that extra energy yield can be harvested by choosing the module concept and optimized tab width for each climate. The optimized half-cell modules benefit of 4.12% and 4.97% extra annual energy yield compared to full-cell modules in moderate and desert climates correspondingly. These values increase respectively by transition to third-cell modules to 5.2% and 5.68% at moderate and desert environments

Investigation of cell-to-module (CTM) ratios of PV modules by analysis of loss and gain mechanisms

The output power of a solar module is the sum of the powers of all the individual cells in the module multiplied by the cell-to-module (CTM) power ratio. The CTM ratio is determined by interacting optical losses and gains as well as by electrical losses. Higher efficiency and output power at the module level can be achieved by using novel ideas in module technology. This paper reviews methods for reducing different optical and electrical loss mechanisms in PV modules and for increasing the optical gains in order to achieve higher CTM ratios. Various solutions for optimizing PV modules by means of simulations and experimental prototypes are recommended. Finally, it is shown that designing PV modules on the basis of standard test conditions (STC) alone is not adequate, and that, to achieve higher CTM ratios by improving the module designs in respect of environmental conditions, an energy yield analysis is essential

Techno-Economic Assessment of Soiling Losses and Mitigation Strategies for Solar Power Generation

Soiling consists of the deposition of contaminants onto photovoltaic (PV) modules or mirrors and tubes of concentrated solar power systems (CSPs). It often results in a drastic reduction of power generation, which potentially renders an installation economically unviable and therefore must be mitigated. On the other hand, the corresponding costs for cleaning can significantly increase the price of energy generated. In this work, the importance of soiling is assessed for the global PV and CSP key markets. Even in optimized cleaning scenarios, soiling reduces the current global solar power production by at least 3%–4%, with at least 3–5 billion € annual revenue losses, which could rise to 4%–7%, and more than 4–7 billion € losses, in 2023. Therefore, taking into account the underlying physics of natural soiling processes and the regional cleaning costs, a techno-economic assessment of current and proposed soiling mitigation strategies such as innovative coating materials is presented. Accordingly, the research and development needs and challenges in addressing soiling are discussed