Modeling and Detection of Hotspot in Shaded Photovoltaic Cells

In this paper, we address the problem of modeling the thermal behavior of photovoltaic (PV) cells undergoing a hotspot condition. In case of shading, PV cells may experience a dramatic temperature increase, with consequent reduction of the provided power. Our model has been validated against experimental data, and has highlighted a counter-intuitive PV cell behavior, that should be considered to improve the energy efficiency of PV arrays. Then, we propose a hotspot detection scheme, enabling to identify the PV module that is under hotspot condition. Such a scheme can be used to avoid the permanent damage of the cells under hotspot, thus their drawback on the power efficiency of the entire PV system

Review of mismatch mitigation techniques for PV modules

The installation of photovoltaic (PV) systems is continuously increasing in both standalone and grid-connected applications. The energy conversion from solar PV modules is not very efficient, but it is clean and green, which makes it valuable. The energy output from the PV modules is highly affected by the operating conditions. Varying operating conditions may lead to faults in PV modules, e.g. the mismatch faults, which may occur due to shadows over the modules. Consequently, the entire PV system performance in terms of energy production and lifetime is degraded. To address this issue, mismatch mitigation techniques have been developed in the literature. In this context, this study provides a review of the state-of-the-art mismatch mitigation techniques, and operational principles of both passive and active techniques are briefed for better understanding. A comparison is presented among all the techniques in terms of component count, complexity, efficiency, cost, control, functional reliability, and appearance of local maximums. Selected techniques are also benchmarked through simulations. This review serves as a guide to select suitable techniques according to the corresponding requirements and applications. More importantly, it is expected to spark new ideas to develop advanced mismatch mitigation techniques.</p

Power dissipation analysis of PV module under partial shading

Photovoltaic (PV) generation has been growing dramatically over the last years and it ranges from small, rooftop-mounted or building integrated systems, to large utility scale power stations. Especially for rooftop-mounted PV system, PV modules are serially connected to match with PV inverter input voltage specification. For serially connected PV system, shading is a problem since the shaded PV module reduces the output whole string of PV modules. The excess power from the unshaded PV module is dissipated in the shaded PV module. In this paper, power dissipation of PV module under partial shading is analyzed with circuit analysis for series connected PV modules. The specific current and voltage operating point of the shaded PV module are analyzed under shading. PSIM simulation tool is used to verify the power dissipation analysis. When there is no bypass diode and three solar modules are connected in series, upto 39.1% of the total maximum PV power is dissipated in the shaded PV module. On the other hand, when the bypass is attached, 0.3% of the total maximum power is generated as a loss in the shaded PV module. The proposed analysis technique of shaded PV module could be used in PV system performance analysis, especially for maximum power point tracking (MPPT) performance

Fault Resilient and Reconfigurable Power Management Using Photovoltaic Integrated with CMOS Switches

A Photovoltaic (PV) cell is a device which converts light incident upon it to electric current. The push for green energy due to global warming and diminution of fossil fuels opens up a huge market for PV cells. Hence, a lot of interest is being garnered for using PV cells for various applications. However, a PV module\u27s performance degrades due to many anomalies such as failure of individual PV cell within a module, the opening of interconnection, a short circuit in the connection, failure of bypass diode, failure in voltage regulator or partial shading. To some extent all of these issues can be addressed by introducing a transistor as a switch in a PV module. This kind of architecture also enables the PV module to switch between high voltage with low current or high current with low voltage. Moreover, such architecture is handy when PV modules are deployed at remote locations where manual intervention in the case of fault or power management becomes too expensive or impossible. With advancements in semiconductor processing, the MOSFET switches can now be integrated with a PV cell for improved reliability. In this research project, we introduced addressable switches for PV cell that enable the creation of real-time reconfigurable power buses or power island. Moreover, for PV module deployed at a remote location, we have installed an architecture that let the PV module self-detect faulty PV cells or partial shading condition. Such algorithms detect faulty PV cells or PV cells under partial shading within the module such that the performance of the PV module does not become degraded. The algorithms actively use an embedded computing device to predict the output power based on a number of PV cells connected in series and parallel; then the computed power is compared with the measured power for faulty condition detection. Typically, for achieving such kind of computing architecture a single-diode based PV module modeling technique is used. However, all of these modeling techniques have an exponential term due to the presence of a diode, the computing of output power and performance of PV module becomes power intensive and it is difficult to implement on an embedded system. Also, due to the presence of the exponential term, there is no closed form solution for IPV versus VPV (output current of PV cell versus output voltage of a PV cell). We have introduced a PV module modeling using an N-channel MOSFET transistor that doesn\u27t have an exponential term. Moreover, a quadratic equation based solution is obtained that can be solved for calculating the load current. Using the same technique PV module can be also be modeled for various configuration. Additionally, with MOSFET based PV cells modeling enables the modeling CMOS-with-PV which is also presented in this work

A New Design for Smart Photovoltaic Module with Fault Detection Properties

Solar power places the third in the renewable energy around the world. To provide such power, huge Photovoltaic (PV) plants are manufactured and installed all over the world. In such plants, faults occur in different stages of the electrical generation process. This paper proposes a new design of a smart PV module that detects and locates faults in the essential material of the PV plants, the PV module. For this aim, Hall Effect sensors have been connected to each substring in a PV module to provide real-time readings from the substrings. These readings have been processed by an algorithm that detects faults and differentiate the normal overall shading from the abnormal shading cases on the PV module. these substrings are designed to be demountable on the PV module for replacement if a sever permanent damage happens. Detecting and locating such faults with this design can save both, time and cost in the repairing process, and early maintenance in such cases provides a longer lifespan of a PV module

In-Field Solar Panel Assessment and Fault Diagnosis

Photovoltaic energy is a green energy that suit from small houses to high-power stations spanning large areas. In such large areas, monitoring individual panels can be a tedious task, especially if it was required to identify operational faults of these panels. Photovoltaic 4.0 technology depend on collecting data from each station and feeding them to a central processing system that can analyze operation data and hopefully locate when a fault happens. In such method, it is crucial to be accurate as much as possible and for measuring device to be accurate as well to have a clear judgement. In this work, we build an analysis module at the center of a photovoltaic 4.0 station implemented in the American University in Cairo. The model is comprehensive in nature and is capable of modelling from individual cell level to the whole panel level as well as dealing with measurement issues to have a good judgement at the end. The used model is based on single-diode model of a solar panel and is capable of modelling solar panels in different environmental conditions and is validated against datasheet and actual measurement. Source code for the analysis module and the dataset are provided. It was shown that Laudani’s method of parameter extraction is more successful compared to Stonelli’s method and translating circuit parameters at different environmental conditions proved to be successful and matching to datasheets. Besides, it provided sufficient predictions without need to an actual weather station. The proposed analysis module provided insights about dusty conditions and irregularities that may exist in solar panel characterizer

PV faults: Overview, modeling, prevention and detection techniques

pre-printRecent PV faults and subsequent fire-hazards on April 5, 2009, in Bakersfield, California, and April 16, 2011, in Mount Holly, North Carolina provide evidence of a lack of knowledge among PV system manufacturers and installers about different PV faults. The conducted survey within the scope of this paper describes various faults in a PV plant, and explains the limitations of existing detection and suppression techniques. Different fault detection techniques proposed in literatures have been discussed and it was concluded that there is no universal fault detection technique that can detect and classify all faults in a PV system. Moreover, this digest proposes a transmission line model for PV panels that can be useful for interpreting faults in PV using different refelectomery methods

Performance Analysis of Thermal Image Processing-Based Photovoltaic Fault Detection and PV Array Reconfiguration—A Detailed Experimentation

Due to the flexibility, sustainability, affordability, and ease of installation of solar photovoltaic systems, their use has significantly increased over the past two decades. The performance of a solar PV system can be constrained by a variety of external conditions, including hotspots, partial shade, and other minor faults. This causes the PV system to permanently fail and power losses. The power output in a partially shaded solar system is improved in this work by the introduction of a fault classifier based on thermal image analysis with a reconfiguration algorithm. For that purpose, the entire PV array is divided into two parts, with one of these being the male part and the other being the female part. MOSFET switches are used to build the switching matrix circuit that connects these parts. The Flir T420bx thermal camera captures thermal pictures, and MATLAB/Simulink® is used to extract the image properties. The pairing reconfiguration pattern is found using an algorithm based on image processing and the image attributes. The switching signals to the switching circuit are triggered by an Arduino controller. The image attributes of the thermal images may also be used to categorize PV system defects. This reconfiguration technique is easy, simple to use, and it can also be used to check the health of each PV module. The performance of the proposed work was validated using a 5 kW PV system with a 4 × 5 TCT array configuration at Sethu Institute of Technology’s renewable energy lab in India. The proposed method was simulated using the MATLAB-Simulink software program, and the outcomes were verified on different hardware setups.publishedVersio

A Comprehensive Review on Bypass Diode Application on Photovoltaic Modules

Solar photovoltaic (PV) energy has shown significant expansion on the installed capacity over the last years. Most of its power systems are installed on rooftops, integrated into buildings. Considering the fast development of PV plants, it has becoming even more critical to understand the performance and reliability of such systems. One of the most common problems faced in PV plants occurs when solar cells receive non-uniform irradiance or partially shaded. The consequences of shading generally are prevented by bypass diodes. A significant number of studies and technical reports have been published as of today, based on extensive experience from research and field feedbacks. However, such material has not been cataloged or analyzed from a perspective of the technological evolution of bypass diodes devices. This paper presents a comprehensive review and highlights recent advances, ongoing research, and prospects, as reported in the literature, on bypass diode application on photovoltaic modules. First, it outlines the shading effect and hotspot problem on PV modules. Following, it explains bypass diodes’ working principle, as well as discusses how such devices can impact power output and PV modules’ reliability. Then, it gives a thorough review of recently published research, as well as the state of the art in the field. In conclusion, it makes a discussion on the overview and challenges to bypass diode as a mitigation technique