1. Introduction
Renewables are spreading worldwide due to several reasons such as minimal operating costs and privileged access to electricity grids. They were the only source of electricity to record demand growth worldwide over the last year by around 256 giga watts (GW), consisting of 54.4% solar PV, around 36.3% wind power, 7.6% hydropower, around 1.8% biopower, and less than 1% geothermal power and concentrated solar power (CSP); in total, the use of renewables has increased nearly 29%. This was recorded as the highest share of renewables among global electricity sources in history [
1,
2]. According to recent operational measurements, a monthly decrease of more than 20% of the worldwide electricity demand was observed due to the effects of COVID-19. Moreover, around 4% of universal electricity demand decreased in 2020, and the demand for coal and oil decreased by nearly 8% and 5%, respectively [
3]. Investments in renewable energy resources increased in 2019 by 2%, reaching around 300 billion USD, with 32 countries having a minimum of 10 GW of renewable power capacity, in contrast with only 19 countries ten years before [
4]. The expansion of the PV market over the past few years is a result of several factors, such as (a) the increasing number of PV manufacturers leading to a decrease in the cost of PV modules, (b) a rising demand for electricity, (c) the ongoing wars and events all over the world, and (d) the desire to decrease the effects of carbon dioxide and other greenhouse gases [
5]. Several applications use PV modules such as Earth-orbiting Solar Power Satellites (SPSs), photovoltaic pumps for irrigation systems, and remote off-grid systems. Large PV farms have been installed worldwide, such as the New and Renewable Energy Agency (NREA)’s 37.5 km
2 Benban Solar Park in Egypt, which reaches around 1.8 GW [
6]. To study these systems thoroughly, an accurate model for the PV cell model is needed under different environmental conditions to obtain data on several aspects, such as Maximum Power Point Tracking (MPPT) and various grid operations [
7]. All losses inside the cell and
I–
V characteristics should be considered in order to accurately model PV cells during the study. The ideal PV cell is represented by a photo-generated current supply (Iph) affected by the solar irradiance (G) landing on the cell [
8,
9]. Furthermore, different losses such as optical losses in the PN (positive–negative) junction of the cell (represented in the single diode model) [
10], recombination losses due to the space charge region (SCR), which is defined in the double-diode (DD) model [
11,
12], and losses in the defect region and grain boundaries (described in the triple-diode (TD) model) [
13,
14] must be taken into consideration.
The main five parameters in the single diode (SD) model are photo-generated current (
Iph), ideality factor (a), the diode cut-off region current (
Io), which represents the diode parameters, along with series resistance (
Rs) which indicates the summation of the resistance of the terminals on the external surfaces, and the resistances of the bulk and diffuse layers for the PN junction on the outer sides. Additionally, parallel resistance (
Rp) arises from the PV surface and bulk irregularities, along with current losses across the edge of the cell [
10]. Another couple of variables representing the second diode are added for the DD model. In comparison, another two variables for the third diode (TD) are added to the model, making it nine parameters in total for this model.
The single diode (SD) model was widely used because of its directness in parameter calculations, simple nature, and adequate accuracy level. However, this model had less accuracy in open-circuit voltage at low irradiances due to recombination losses [
15]. This effect was considered when considering the double diode (DD) model by introducing a further diode standing for the recombination losses. This extra diode increases the precision of the DD model, but it also leads to more complexity, with two additional parameters added to the previous five; the second diode cut-off region current and its ideality factor [
16]. Furthermore, the triple diode (TD) model was introduced with greater precision by adding a third diode representing the leakage current and the effect of grain boundaries [
17]. While this model addresses most of the losses, it has more complicated calculations to calculate its parameters with an additional two parameters (reverse saturation current and ideality factor) added to represent the third diode [
18].
Multiple methods have been used to deduce the previously mentioned parameters. Generally, elements from the datasheet (Isc, Voc, Im, Vm) are used to extract the parameters at standard conditions (G = 1000 W/m2 and T = 25 °C) using analytical, iterative, and meta-heuristic optimization strategies.
Meta-heuristic techniques are used to acquire the parameters of the SD model [
19], DD model [
20] and TD model [
21] by using the root-mean-square deviation, which requires the difference between the actual and calculated current values. These algorithms, such as the genetic algorithm (GA) [
22], particle swarm optimization (PSO) technique [
23], bacterial foraging (BF) technique [
24], hybrid artificial bee colony (ABC) and trust-region-reflective (TRR) technique [
25], whale optimization algorithm (WOA) [
26], shuffled frog leaping algorithm (SFLA) [
27], hybrid firefly technique and pattern search technique [
28], harmony search algorithm (HSA) [
29], artificial fish swarm algorithm (AFSA) [
30], trust-region-reflective (TRR) algorithm [
25], and cuckoo search (CS) algorithm [
31] aim to minimize the error. However, each of the techniques above has its limitations and merits. Using the conventional GA has the benefit of simplifying the limitation, but the finite length of the bit string provides an obstacle to obtaining the real values of the variables [
32]. The use of a penalty function was presented as a solution to the major drawback of using standard DE: the premature convergence of parameters to local minima [
33]. HSA is impacted deeply by the initial population [
29], PSO is prone to premature convergence as it lacks the right mechanism for balancing exploration between the local and global particles search [
34], and ABC has a poor response under operating conditions [
35]. CS has a slow convergence rate as it does not use local search to enhance the convergence speed when the confined search is close to global or local minima but relies solely on Lévy flight to find new parameter solutions [
36]. For AFSA, it was deduced that the accumulation of few fishes in local optima leads to slow convergence speed [
35]. It was deduced that the use of the analytical methods is complicated in the TD model due to the number of parameters. Therefore, the use of the meta-heuristic algorithms was met with appreciation, especially the new algorithms.
In this paper, the advantages and disadvantages of the single, double, and triple diode model (reported in previous studies) prompted the authors to apply the hybrid optimization technique to deduce the parameters for the TD model. For a realistic study of the TD model, two well-known commercial PV modules were picked to be studied (Kyocera KCG200T and Canadian solar CS6K-280M). Experimental readings for temperature, irradiance, and output current and voltage were taken for these modules in 2019. To ensure the study’s credibility, the parameters obtained using the proposed optimization technique and datasheet parameters are compared to those obtained from the measured readings. The hybrid particle swarm grey wolf optimization (PSOGWO) technique is applied in this study as the hybridization of optimization techniques is a trending direction these days and is used in multiple studies, as hybridization merges the merits of several optimization techniques and diminishes the weak points in each technique [
37,
38]. These hybrid techniques are especially beneficial for renewable energy studies due to the intermittence of these energy sources and their non-linear nature.
The remainder of this paper is organized in the following sequence, with
Section 2 explaining the mathematical representation of the triple diode model for the PV module and formulating the problem.
Section 3 discusses and demonstrates the PSO and GWO optimization techniques leading to the hybrid PSOGWO optimization technique. In
Section 4, the results are displayed and discussed, then verified by comparing them to results obtained from other techniques (e.g., WOA and SFO); they are also compared to results from experimental readings for further verification.
6. Conclusions
The main target is to obtain the optimal configuration of the TD model of the PV module. These parameters are beneficial for obtaining an accurate PV model, which is extremely important for PV-powered systems’ modeling studies. Due to the lack of data presented by the PV suppliers, the hybrid PSOGWO algorithm is utilized to reach the optimal configuration of the TD model. The model is built using equations for the TD model and parameters from the datasheet (Isc, VOC, etc.). The objective of using the optimization technique is to minimize the current deviation. Aiming for a realistic study, the proposed technique is applied to two well-known PV modules, Kyocera and Canadian. The obtained parameters are validated and compared with those obtained from other recent algorithms such as SFO, GA, and WOA. The simulation outcomes ensure the competitiveness and robustness of the proposed model over the other techniques under comparison.
Moreover, the analytical results are evaluated concerning experimental results, and the error was proved to be satisfactory and within acceptable ranges, recording values below 0.5% and reaching in certain cases 0.07% and 0.08% with fitness values of 3.14 × 10−10 in the case of Kyocera and 1.59 × 10−10 in case of the Canadian solar cell. Accordingly, with the help of the hybrid PSOGWO algorithm, an accurate PV model was obtained. This model may also be useful for power electronics studies that need an accurate, efficient, and dependable PV model, and in studies for grid-connected PV systems.
Finally, reducing greenhouse gas emissions requires reliance on renewable energy resources such as solar energy, which is regarded as a clean and sustainable energy source. However, the efficient use of solar PV necessitates accurate modeling of the PV cells to correctly estimate the parameters of equivalent circuit models, particularly in the TD model, which is one of the most precise PV models. The mathematical and experimental results obtained in this work clearly verified that the hybrid PSOGWO algorithm performed well at different irradiance and temperature levels for the investigated commercial PV modules. This allows for the proper and efficient use of solar PV modeling in different studies..