With increasing installations of photovoltaic (PV) systems, interest in power forecasting has also increased. Inaccurate forecasts would result in substantial economic losses and system reliability issues. The correlation between weather variables and PV power is critical to ensure the efficient use of energy in PV systems. A key step toward accurate power forecasting is estimating the output from a PV system based on known environmental input data. In this research, all available weather data are used to predict the PV power. Meteorological and power data are then analyzed using a statistical approach to identify the order of significance of the input variables. Then, a predictive model is suggested as a function of irradiance, ambient temperature, wind speed, and relative humidity. The model produces a root mean square error of 4.957% and a mean absolute percentage error of 5.468% during the measurement period and over the entire range of irradiation.
Unlike conventional photovoltaic (PV) modules that generate power by absorbing light through the front side only, a bifacial PV module can generate power by absorbing light through the rear as well as the front, which would lead to an enhancement of power generation. Particularly, bifacial PV modules would have the advantage of lower power loss in shaded environments than monofacial PV modules, thanks to the light absorbed through the rear side. To predict the power of a bifacial PV module in a shaded environment, modeling is suggested by considering the shaded areas, the operational status of the bypass diodes, and the temperature of the bifacial PV module. To verify the power prediction of a bifacial PV module with a shaded area, modeled and measured powers are compared, showing error rates of 7.28%. From the results of the power loss experiments for bifacial and monofacial PV modules in shaded environments, it is confirmed that the bifacial PV module shows a relatively low power loss rate when compared with the monofacial PV module, with a power loss rate being 87.26% of the rate for the monofacial PV module. Index Terms-Bifacial c-Si PV module, bypass diode, shading. I. INTRODUCTION O NE of the major interests of the photovoltaic (PV) power plant operators is the reduction in the installation cost of PV power generation systems [1]. It has been reported that the price of PV modules accounted for 24% of the unit cost of commercial PV power systems in 2018 [2]. One of the possible ways for lowering the cost of installing a PV power system would be the development of a highly efficient solar cell and module that could generate higher power for a given area. A bifacial PV module is a highly efficient PV module that can absorb light not only through the front, but also through the rear. Power generated through the rear side of a bifacial PV module varies with different reflective conditions [3]. However, the standardization of the output of a bifacial c-Si PV module under standard test condition (STC) was in
Fault detection and repair of the components of photovoltaic (PV) systems are essential to avoid economic losses and facility accidents, thereby ensuring reliable and safe systems. This article presents a method to detect faults in a PV system based on power ratio (PR), voltage ratio (VR), and current ratio (IR). The lower control limit (LCL) and upper control limit (UCL) of each ratio were defined using the data of a test site system under normal operating conditions. If PR exceeded the set range, the algorithm considered a fault. Subsequently, PR and IR were examined via the algorithm to diagnose faults in the system as series, parallel, or total faults. The results showed that PR exceeded the designated range between LCL (0.93) and UCL (1.02) by dropping to 0.91-0.68, 0.88-0.62, and 0.66-0.33 for series, total, and parallel faults, respectively. Moreover, VR exceeded the LCL (0.99) and UCL (1.01) by 0.95-0.69 and 0.91-0.62 for series and total faults, respectively, but not under parallel faults condition. IR did not change in series and total faults but exceeded the range of LCL (0.93) and UCL (1.05) by dropping to 0.66-0.33. Thus, faults in PV systems can be detected and diagnosed by analyzing quantitative output values.
Abstract:Underwater grounding methods could be applied in deep water for grounding a floating PV (photovoltaic) system. However, the depth at which the electrodes should be located is a controversial subject. In this study, grounding resistance was measured for the first time by analyzing the water temperature at different water depths in an area where a floating PV system is installed. The theoretical calculation of the grounding resistance has a maximum error range of 8% compared to the experimentally measured data. In order to meet the electrical safety standards of a floating PV system, a number of electrodes were connected in parallel. In addition, the distance between electrodes and number of electrodes were considered in the test to obtain a formula for the grounding resistance. In addition, the coefficient of corrosion was obtained from an electrode installed underwater a year ago, and it was added to the formula. Through this analysis, it is possible to predict the grounding resistance prior to installing the floating PV system. Furthermore, the electrical safety of the floating PV system could be achieved by considering the seasonal changes in water temperature.
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