Output-Power Enhancement for Hot Spotted Polycrystalline Photovoltaic Solar Cells

IEEE Trans. Device Mater. Relib.

Holmes

Mather

2019

Self Cite

This paper presents a novel detection technique for inspecting solar cells micro cracks. Initially, the solar cell is captured using Electroluminescence (EL) method, then processed by the proposed technique. The technique consist of three stages, the first stage combines two images, the first image is the crackfree (healthy) solar cell, whereas the second is the cracked solar cell image. Both output images processed into a bit-by-bit gridding technique, which enables the detection of all bits in the considered area of the cracked solar cell. The second stage uses an OR gate between each of the examined bits for both healthy and cracked solar cells. The final calibrated image presents a high quality, and low noise structure, thus easier to identify the micro crack size, location and its orientation. In order to examine the effectiveness of the proposed technique, three different cracked PV solar cells have been examined. The results show that the micro cracks size, orientation, and location is more visible using the proposed technique. In addition, the developed technique has been validated using a full scale PV module, and compared with up to date available PV micro crack detection methods.

Section: Discussionmentioning

confidence: 99%

Novel Photovoltaic Micro Crack Detection Technique

IEEE Trans. Device Mater. Relib.

Holmes

Mather

2019

Self Cite

“…Inaccuracies in determined degradation rates lead to amplified financial risks in the PV sector. Technically, degradation mechanisms are important to understand because they could lead to PV system failures [3]. Typically, a 10% decline is considered a failure, but there is no compromise on the definition of failure [4], because a high-efficiency module degraded by 50% may still have a higher efficiency than a non-degraded module from a less efficient technology.…”

Section: Introductionmentioning

confidence: 99%

Photovoltaic Degradation Rate Affected by Different Weather Conditions: A Case Study Based on PV Systems in the UK and Australia

Alrashidi

2020

Electronics

Self Cite

This article presents the analysis of degradation rate over 10 years (2008 to 2017) for six different photovoltaic (PV) sites located in the United Kingdom (mainly affected by cold weather conditions) and Australia (PV affected by hot weather conditions). The analysis of the degradation rate was carried out using the year-on-year (YOY) degradation technique. It was found that the degradation rate in the UK systems varies from −1.05% and −1.16%/year. Whereas a higher degradation ranging from −1.35% to −1.46%/year is observed for the PV systems installed in Australia. Additionally, it was found that in the Australian PV systems multiple faulty PV bypass diodes are present due to the rapid change in the ambient temperature and uneven solar irradiance levels influencing the PV modules. However, in cold weather conditions (such as in the Northern UK) none of the bypass diodes were damaged over the considered PV exposure period. Furthermore, the number of PV hot spots have also been observed, where it was found that in the UK-based PV systems the number of hot spotted PV modules are less than those found in the Australian systems. Finally, the analysis of the monthly performance ratio (PR) was calculated. It was found that the mean monthly PR is equal to 88.81% and 86.35% for PV systems installed in the UK and Australia, respectively.There are various references in the literature that include the degradation rate of PV systems worldwide. However, there are a lack of references found in the literature describing the behavior and degradation analysis of existing PV systems in the United Kingdom and Australia. Therefore, in this article, the degradation rate of six PV sites installed in three different locations in the UK and Australia are examined over a period of ten years (2008 to 2017). Before moving to the methodology, it is indeed important to have an overview of the degradation rate across multiple regions in the world, which will be summarized as follows:• United States of America (USA): The USA is placed on the top five countries leading the PV technology worldwide [6]. In 1977, the Department of Energy established the Solar Energy Research Institute in Golden, Colorado. In 1991, it was renamed as the NREL. Outdoor testing of modules and sub-modules started at the Solar Energy Research Institute in 1982. When amorphous silicon (a-Si) modules first became commercially available, NREL began to report degradation rate that were considerably higher than −1.0%/year [7]. In [8] and [9], similar results of the PV degradation were found in small (<10 kWp) size PV installations, followed by a yearly degradation rate of approximate −0.8% to −1.25%/year. • Europe: The terrestrial focus of PV industry in Europe can be traced to the oil crisis of the 1970s. The development and institution of PV sites can be divided into publicly and privately funded projects. The publicly funded portion in Europe can be additionally divided into the umbrella organization of the Commission of the European Communities and individual national p...

“…In 2018, two hot-spot mitigation techniques developed by Dhimish et al [18]. Both techniques consists of several MOSFETs connected to the PV module in order to switch ON/OFF the hot-spotted PV solar string.…”

Section: Introductionmentioning

confidence: 99%

Assessing MPPT Techniques on Hot-Spotted and Partially Shaded Photovoltaic Modules: Comprehensive Review Based on Experimental Data

IEEE Trans. Electron Devices

2019

Self Cite

Hot-spotting is a reliability problem influencing photovoltaic (PV) modules, where a mismatched solar cell/cells heat up significantly and reduce the output power of the affected PV module. Therefore, in this paper, a succinct comparison of seven different state-of-the-art MPPT techniques are demonstrated, doing useful comparisons with respect to amount of power extracted, hence calculate their tracking accuracy. The MPPT techniques have been embedded into a commercial off-the-shelf MPPT unit, accordingly running different experiments on multiple hot-spotted PV modules. Furthermore, the comparison includes real-time long-term data measurements over several days and months of validation. Evidently, it was found that both fast changing MPPT (FC-MPPT) and the modified beta (M-Beta) techniques are best to use with PV modules affected by hot-spotted solar cells as well as during partial shading conditions, on average, their tracking accuracy ranging from 92% to 94%. Ultimately, the minimum tracking accuracy is below 93% obtained for direct PWM voltage controller (D-PWM-VC) MPPT technique.