File Name: potential induced degradation of solar cells and panels creator.zip
Solar energy is a renewable type, clean, and inexhaustible which is sufficiently available on the Algerian territory. The importance of this work is based on exploiting solar energy to produce electricity. In this work, a prototype of new artificial solar tree is proposed experimentally by using material available in the local market: 25 solar panels, metal support, electrical queues, regulator, and battery.
In order to evaluate a photovoltaic PV plant performance, payback time, profitability and environmental impact, an analysis must be made of plant maintenance needs, module and wiring degradation, mismatches and dust effects and PV cell defects and faults.
Although a wide range of studies can be found that show the theory and laboratory testing of how these circumstances may affect PV production, very few studies in the field have covered or quantified real degradation effects and faults using a systematic procedure.
The authors have therefore reviewed the conditions of PV plants operating in Southern Europe, examining the most frequently found faults and types of degradation, and they look at how novel technologies, such as geographic information system GIS applications, can help maintainers, owners, and promoters to supervise and locate damaged PV modules and monitor their evolution and impact on plant working conditions.
GIS applications in this field allow the organization of a geo-referenced database of the system, locating and supervising the thirds of each PV cell in the power plant. With this information, investors and maintainers can exert increased control on the PV plant performance and conduct better preventive maintenance measures. The examples given demonstrate that these sorts of applications can be applied both to large PV plants and to domestic installations.
Solar Panels and Photovoltaic Materials. The operation and maintenance of a photovoltaic PV power plant is of extreme importance to guarantee its optimal performance. Effective maintenance involves at the least semi-automatic analysis and alerts. In this way, the maintenance operator is capable of making immediate decisions to solve safety problems and minimize power losses [ 1 ].
Moreover, monitoring is not just a regular recording of data but involves a more detailed analysis in order to prevent possible malfunctions associated with power and, in the end, economic losses. Thus, the development of automatic supervision tools to help maintainers to carry out an effective supervision of the power plant and, what is more important, to monitor the evolution of the modules behavior in an easy and feasible way is of great interest in the industry.
Furthermore, the detection of operating failures in a timely fashion through the evaluation of panels over time means that automated monitoring is, in fact, absolutely necessary. Such monitoring will lead to the early replacement of poorly performing components, preventive maintenance policies, and better management of plants.
For device manufacturers, performance evaluations of their products can be used as a benchmark of their quality manufacturing processes. For PV plant promoters and owners, realistic performance data is essential for investment decision-making.
These techniques, moreover, do not address preventative maintenance strategies or effective economical programs for the replacement of components.
In addition, these systems do not integrate geo-references that may help to improve the application of preventative maintenance strategies. New methodologies are needed to locate and analyze performance and malfunction of plant components on a global scale.
Despite the great value of analysis carried out in the laboratory, it can often be of little help when applied to the real operation of maintenance plans. Test conditions in a laboratory may allow for a complete analysis of PV components, but owners can ill afford to close an entire installation or part thereof for equivalent testing in the field. Besides, laboratory test conditions are unlikely to fully typify working conditions in a real field. As such, laboratory test results and, more importantly, any conclusions drawn from them are likely to be decontextualized.
On the other hand, carrying out systematic procedural techniques in the field under changing environmental and climatic conditions is in no way easy. Integrated geographic information system GIS platforms will allow test-related information to be comprehensively organized and geo-referenced, providing significant benefits. One such benefit is the fact that the impact of a single defective component on the overall performance of a plant can be analyzed.
Predictive techniques can then be used to analyze deviations in the behavior of supposedly viable components and forecast possible outage in areas of the PV plant. This chapter is organized into four further sections. First, a systematic review of the most common PV faults is undertaken. Then, the fundamentals of GIS and how they can be applied to PV maintenance and fault supervision are presented. In section three, the application of a GIS tool to both a large PV plant kWp and a domestic installation 9 kWp is fully described and results of the implementation of both examples are shown.
Finally, the last section includes the main conclusions and some future research directions. The bibliography defines a failure in a photovoltaic module as an effect that degrades the module power output which is not reversed by normal operation or which, on the other hand, creates a safety issue.
Evidently, both of these effects can occur at the same time. As such, degradation of wiring or modules, PV cell defects and malfunctions, dust, and mismatches can be considered to be failures of PV modules [ 5 ] and purely esthetic problems are not. This consists of the loss of adhesion between the glass, the encapsulation, the active layers, and the subsequent layers [ 6 ], which can cause loss of current power in the photovoltaic modules.
Loss of adhesion may occur for various reasons. Large thin film modules and certain other types of modules sometimes contain an additional transparent conductive oxide TCO layer, which may lose adhesion with the adjacent glass layer [ 6 ].
If the loss of adhesion is due to contamination, perhaps from cleaning, or environmental factors, then delamination will often take place, followed by moisture entering and, in due course, corrosion. Delamination leads to reflection of light and a subsequent loss of power in the modules. In most cases delamination can be detected by visual inspection, with the degree of layer detachment being quantified by use of a reflectometer.
Some delaminations, however, cannot be identified in this way and so methods such as pulsed active thermography or lock-in thermography can be used, while smaller delaminations can be detected with ultrasound scanners and X-ray tomography. The latter methods are slow [ 7 ] but provide a much higher resolution. The multilayer composites that make up PV module backsheet films comprise three or more polymer layers. Outer layers provide resistance to weathering factors such as sunlight and humidity and are often made from fluoropolymers with polyvinyl fluoride PVF , polyamide PA , or polyethylene terephthalate PET [ 8 ] being popular choices.
Backsheet failures include yellowing, brittleness that leads to cracking, and delamination within the multilayer composite. Delamination and cracking allow water vapor and oxygen into the PV module and are considered to be the worst kind of failures within backsheets as they cause problems with isolation and subsequently can cause safety issues [ 9 ]. Water vapor critically affects degradation phenomena such as decomposition of the encapsulation, corrosion of the metal parts, and potential induced degradation PID of the PV modules.
Such failures impact on the performance of a PV module and shorten its lifespan. Yellowing, on the other hand, has not been reported as having an influence on the electrical performance of modules. Junction boxes are attached to the back of modules and protect the connections to the external terminals. Bypass diodes in the junction boxes protect cells in a series when hot spots occur due to partial shadowing of the module [ 5 ].
The formation of moisture due to faulty adhesive can lead to wiring degradation that can be the cause of electrical arcing resulting in the potential for fire or threat to human life. Mechanical breakages usually consist of cracks in the frame produced by poor handling or extreme winter snow loads. Degradation of the encapsulation material normally ethylene vinyl acetate or EVA is an esthetic issue that does not usually affect the performance of a module.
It can, however, lead to an average current loss of 0. Rising temperatures, the photo-degradation of EVA by UV radiation, and the existence of molecular oxygen lead to the production of acetic acid and volatile gases, that are trapped within the module, and can produce delamination or the formation of bubbles [ 11 ]. The presence of acetic acid in a PV module is linked to several PV module failures due to its corrosive effects on cell metal, which may lead to an increased series resistance and hence losses in module performance [ 12 , 13 ].
Some studies refer to discoloration as degradation rather than failure, as discoloration leads typically to lower performance but not necessarily to failure [ 6 ]. On the other hand, inappropriate temperatures or an excessively long lamination procedure [ 14 ] during the manufacturing of the photovoltaic module can cause bubbles of gas to be formed either as a direct or as an indirect consequence of melting and solidification processes Figure 1.
In Figure 1 a an EVA discoloration can be appreciated while in Figure 1 b we can observe an example of a bubble formed over a metal contact.
PV cells are made of silicon so they are very brittle. Cell cracks are formed in different lengths and orientations in the substrate of the photovoltaic cells and often cannot be seen easily. Figure 2 shows a clear example. Cell cracks may occur during or after production. Major sources of cell cracks are during packaging and transport or during the reloading of PV modules and installation in the field. Small cell cracks show a great tendency to develop into larger, wider cracks during operation of the solar module due to mechanical stress [ 15 ] from wind or snow load and thermo-mechanical stress [ 16 ] from temperature variations due to changes in weather and intermittent cloud cover.
Apart from the risk of power loss there is also the chance of hot spots being formed. This can happen when a cracked cell has a localized reverse current path in the still active cell part. The cell may reverse bias and the full current will be able to flow along the localized path as a consequence of the missing cell area.
This can cause hot spots and subsequently burn marks [ 17 ]. Snail tracks are discolorations of the silver fingers on solar cells. A significant example can be seen in Figure 3. The effect looks like a snail has passed across the front glass of the PV module. The discoloration takes place on cell cracks that are not visible at the edge of the solar cell. Discoloration speed is initially dependent on seasonal and environmental conditions, such that snail tracks seem to spread faster during summer months and in hot climates [ 5 ].
A typical and very common failure in silicon PV modules is burn marks. This failure occurs due to part of the module becoming very hot and can be because of ribbon breakage, solder bond failure, or localized heating from reverse current flow or other hot spots [ 5 ]. Burn marks can produce power losses and serious safety problems. They are usually located on or closed to the metal contacts of the PV solar cells, such as it can be seen in Figure 4. Hot spots are areas in a photovoltaic module that have very high operating temperatures when compared to surrounding areas.
This may be due to interconnection failures, defects in the cell, dispersion of characteristics between modules of a generator and between cells of the same module connected in series, potential-induced polarization in modules manufactured with novel techniques, or when a cell generates less current than other cells connected in series as a consequence of intermittent cloud cover or partial shading [ 20 ].
As a consequence, the cell becomes polarized the voltage between the terminals becomes negative and starts to dissipate the power generated by the other serial cells in the form of heat. Recently, a new maximum power point tracking MPPT method was proposed to avoid the consequences of hot spots. It is based, firstly, on a bidirectional buck converter to control the operating point of each module and uses a boost converter to control the terminal voltage of each branch.
Potential-induced degradation gives rise to power losses owing to the presence of eddy currents in the PV modules. Its effect can potentially reduce the power of the equipment [ 22 ].
The principal cause of these currents is reported to be voltage gaps between the ground and the module. Cell strings can become disconnected if string interconnected ribbons are weak, which may be caused by large deformations, by the quality of the welds during the production process, or by weak connections between the string and the ribbon.
Small distances between cells can also contribute to interconnected ribbon breakage [ 5 ]. The consequences of this may be a broken cell interconnected ribbon and a subsequent decrease in maximum power point current [ 24 ] or a shunt by a cell interconnected ribbon and a subsequent decrease of open circuit voltage.
Bypass diodes reduce the effects of intermittent cloud cover and partial shading on power generation by limiting reverse voltage potentials [ 5 ]. Power output is decreased significantly without bypass diodes and partial shading may cause local overheating, hot spots, and damage [ 25 ]. A new bypass system has been designed [ 26 ] allowing significant hot spot temperature reduction in both partial and full shading conditions. It relies on a series-connected power metal oxide semiconductor field effect transistor MOSFET that subtracts part of the reverse voltage from the shaded solar cell, thus acting as a voltage divider.
This consists of the lightening of the dark blue tone of certain cells in the PV module. A geographic information system or GIS consists of a set of applications and programs that manage spatially referenced databases, which can be visualized through the use of maps [ 28 ]. It is a powerful and dynamic tool for the analysis of geographical and spatial data, which can also include non-spatial data. A correctly implemented GIS tool provides comprehensive analysis of an area for any activity that entails a spatial component, meaning that GIS technology has wide application in resource management and can be an important tool in any decision-making task with a spatial element.
Content Many electrically qualified persons and plant operators have recently heard or read about an inexplicable power loss. Often, they do not know the exact cause of this effect, known as potential induced degradation PID , and cannot assess whether it is relevant in their given situation. The question of how to identify an affected PV module and what counter measures are recommended always arises. The purpose of this technical information is to describe the background of the PID effect and to explain the various influencing factors. The good news for operators is that there are a number of different corrective measures.
PDF | Since solar energy generation is getting more and more important worldwide PV systems and solar parks are becoming larger consisting.
Potential-induced degradation PID has received considerable attention in recent years due to its detrimental impact on photovoltaic PV module performance under field conditions. While extensive studies have already been conducted in this area, the understanding of the PID phenomena is still incomplete and it remains a major problem in the PV industry. Herein, a critical review of the available literature is given to serve as a one-stop source for understanding the current status of PID research. This paper also aims to provide an overview of future research paths to address PID-related issues.
Photovoltaics PV is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect , a phenomenon studied in physics , photochemistry , and electrochemistry. The photovoltaic effect is commercially utilized for electricity generation and as photosensors. A photovoltaic system employs solar modules , each comprising a number of solar cells , which generate electrical power.
Get ready to see our solar cells where you wouldn't expect any at all. The term solar panel is used colloquially for a photo-voltaic PV module. A PV module is an assembly of photo-voltaic cells mounted in a frame work for installation. Photo-voltaic cells use sunlight as a source of energy and generate direct current electricity.
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Reliability of photovoltaic modules from indoor testing to long-term performance prediction.Omar T. 28.03.2021 at 09:56
In this paper, we discussed the field failures of the brownish discolored lines like snail trails in PV modules.Raijiabrochard1951 28.03.2021 at 15:57
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