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

Abstract

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...

A Review of I–V Tracers for Photovoltaic Modules: Topologies and Challenges

“…In [25], the plotting time of the I-V curve is indicated with this method, and it is given by (4). The use of the tracer is proposed as part of an MPPT controller to identify possible shading conditions of the modules, which is also considered in [17].…”

“…Globally, the PV power generation market in 2020 has installed 139.4, compared to 114.9 GW in 2019 [3], that is, an increase of 21.32%, which indicates the important growth of this type of power source (Figure 1). However, PV modules suffer degradation caused by aging, wear and tear, as well as their outdoor exposure [4], which causes their power to decrease, affecting the overall efficiency of the PV installation [5]. Therefore, preventive maintenance is required to know the current status of each module [6], and predictive maintenance to achieve comprehensive management [7].…”

Statistical Methods for Degradation Estimation and Anomaly Detection in Photovoltaic Plants

“…A PV performance analysis involves the estimation of the long-term degradation rates, that quantify the gradual reduction of performance of a PV system over time. In many cases the degradation rates are calculated based on a metric called the performance ratio (PR) [ 8 , 9 , 10 ], which is the ratio of the measured and nominal power. Variants of the standard PR include a corrected PR that uses a corrected measured power to compensate for the differences in measured irradiance and module temperature, with respect to the Standard Test Conditions (STC).…”

“…Variants of the standard PR include a corrected PR that uses a corrected measured power to compensate for the differences in measured irradiance and module temperature, with respect to the Standard Test Conditions (STC). For example, a corrected PR is used in [ 9 , 11 , 12 ]. PR can be calculated on a yearly, monthly, or daily basis, after which an analysis of the PR time-series is done to evaluate the degradation.…”

“…A simple linear regression model fits a linear model to the raw PR time-series [ 10 ], or to the trend component extracted after seasonal decomposition [ 8 ]. In another approach, the degradation ratio is extracted from the distribution of the year-on-year degradation calculated as the rate of change of the PR between the same days in two subsequent years [ 9 ]. For cases of nonlinear degradation rates, change point analysis has been performed to detect the changes in the degradation slopes, after which linear degradation rates are calculated between every two consecutive points of change [ 14 ].…”