Approximating Shading Ratio Using the Total-Sky Imaging System: An Application for Photovoltaic Systems

Abstract

In recent years, a determined shading ratio of photovoltaic (PV) systems has been broadly reviewed and explained. Observing the shading ratio of PV systems allows us to navigate for PV faults and helps to recognize possible degradation mechanisms. Therefore, this work introduces a novel approximation shading ratio technique using an all-sky imaging system. The proposed solution has the following structure: (i) we determined four all-sky imagers for a region of 25 km2, (ii) computed the cloud images using our new proposed model, called color-adjusted (CA), (iii) computed the shading ratio, and (iv) estimated the global horizontal irradiance (GHI) and consequently, obtained the predicted output power of the PV system. The estimation of the GHI was empirically compared with captured data from two different weather stations; we found that the average accuracy of the proposed technique was within a maximum ±12.7% error rate. In addition, the PV output power approximation accuracy was as high as 97.5% when the shading was zero and reduced to the lowest value of 83% when overcasting conditions affected the examined PV system.

A Review of State-of-the-Art and Short-Term Forecasting Models for Solar PV Power Generation

“…Figure 2 presents the distribution of the five database input sources, of which the models using meteorological records [81][82][83][84] or numerical weather prediction (NWP) [85][86][87] are dominant, accounting for 49% and 25%, respectively. In several studies, 15% of the power generation information was shared from nearby PV power plants [56,59,88], 6% of the studies used satellite images as the input source data [89,90], and some studies combined with sky images have been very promising. Such studies account for 5% of all studies, although further work is needed to correctly identify cloud layers [72,[91][92][93].…”

Artificial Intelligence Techniques for Solar Irradiance and PV Modeling and Forecasting

“…In [6], Dhimish and Lazaridis introduced an innovative approach to estimating the shading ratio of PV systems, a critical parameter for identifying potential PV faults and degradation mechanisms. This technique utilizes an all-sky imaging system and follows a structured process: Firstly, four all-sky imagers are deployed across a 25 km 2 region.…”