1. Introduction
The plant pollution and the fluctuation of fossil fuel prices due to political and economic crises around the world are the main problems that affect the energy field. As well as for the aforementioned drawbacks of conventional energy sources, the fossil fuel is not abundant and sustainable [
1]. Furthermore, the energy demand is dramatically increasing with time, due to the luxury live style demands. Therefore, finding a new sustainable energy source is a hot topic of research. Solar energy has been represented as one of the important and promising alternative energy sources [
2,
3]. The photovoltaic (PV) technology is playing an important role for converting the solar irradiance into direct current electricity. The long-life cycle time of PV and environmentally friendly are presenting the most advantages of this technology [
4]. In addition, the price of PV module is also decreasing overtime [
4]. The basic drawback of PV module is the low efficiency of converting solar energy into electricity [
5]. This issue makes the output of PV module is limited and suffers from weather fluctuations. Therefore, the modeling of PV module has to be more accurate to enable the project administrator to use an appropriate number of PV modules in order to achieve the reliability and cost-effective PV system. Modeling PV module significantly depends on the process of estimating the identification unknown parameters of equivalent electrical circuit of module. These parameters are unknown and sensitive to weather conditions. Generally, estimating PV module parameters is obtained via three approaches; analytical, numerical, and artificial intelligent (AI)-based method [
6]. In analytical method, a relationship is presented between the parameters of PV module under the standard test condition (STC) and other weather condition using manufacturer data [
7]. The importance of analytical approaches is tended to be fast and simple for calculating the parameters [
8]. The main issue of analytical method is the significant deviation between the experimental and simulated performance due to the impact of geographical situation on PV module parameters.
The numerical method is proposed by scholars to overcome the drawbacks of analytical method. In numerical method, all the points of I-V characteristic curve are used based on an iteration method to extract the parameters of PV module [
9]. The numerical method offers an accurate estimation for PV modules parameters than analytical method. The drawbacks of numerical method are its requirement for big I-V data curve, and the accuracy of results is affected by the assumed initial conditions of parameters [
10]. Furthermore, the numerical method needs for great computational resources. A combination of numerical and analytical methods (compound method) have been presented by [
11,
12,
13] to obtain the benefit of the aforementioned methods. The drawbacks of both analytical and numerical methods are still existed in the compound method.
The third type of PV modeling method that based on AI. Many research works adopted artificial neural network (ANN) for modeling PV module [
14]. The ANN-based PV modeling represents as a black box that requires a big data of I-V characteristic points. Moreover, it represents a complex location dependent modeling method.
Due to the reliability and efficiency of metaheuristic algorithms, the last are extensively used for modeling PV module [
15]. The I-V characteristic of PV module is nonlinear, so the metaheuristic is an appropriate choice for handling the modeling problem. Big research efforts are devoted for estimating the parameters of single diode model (SDM) and double diodes model (DDM) of PV module using various metaheuristic algorithms since last decade. On the other hand, a humble research works was devoted for determining the parameters of triple diode model (TDM) of PV module. In [
16], the authors have utilized an iterative process using the PSO algorithm to estimate PV model parameters and by fitting the measured I-V curves to the calculated I-V curves. The series resistance parameter has been considered to vary linearly with the load current through the device. The proposed TDM in [
16] is demonstrated in comparison to the two-diode model, and the findings indicated how the TDM performance is better than DDM. Meanwhile, nine unknown parameters of the TDM PV module have been extracted via a novel implementation of the coyote optimization algorithm (COA) which has been presented in [
17]. The obtained ideal design variables of the presented COA-TDM have been studied against the ideal variables achieved through whale optimization algorithm (WOA)-based TDM PV model, genetic algorithm (GA), and simulated annealing (SA), for both modules (KC200GTand MSX-60). The proposed COA-TDM showed an optimal design variable that are really close to that achieved by applying other metaheuristic optimization algorithms regarding both two commercial PV modules. In [
18] a compound of analytical and an improved differential evolution algorithm called IDEA is presented to identify the parameters of DDM and TDM of PV module. For both the TDM and DDM, the parameters were partially extracted via analytical process (seven TDM parameters and five DDM parameters) and by using optimization techniques (both TDM and DDM have two variables). In [
19] a slime mould algorithm (SMA) is presented according to the slime mould’s natural oscillation. Based on a unique mathematical expression, the SMA is introduced which adapting the weights to collect negative and positive feedback of the slime mould propagation wave. According to the results of [
19], the SMA showed better performance as compared to other heuristic methods in TDM, DDM and SDM. A transient search optimization (TSO) is proposed in [
20] which is based on a novel competent meta-heuristic optimizer and aims to estimate the TDM PV module’s optimal nine-parameter. Different companies have applied the TSO for given objective function to identify three PV modules. Accordingly, the PV’s I-V characteristics have been validated by the measured data with regards to different solar radiations and temperatures. The TSO algorithm has proved his effectiveness as compared to other models as it has been indicated through the convergence curves. Authors in [
21] have customized collected data and mathematical representation of PV model of different diode numbers (SDM/DDM/TDM), where the optimal parameters of the studied approach have been determined according to the fractional chaotic ensemble particle swarm optimizer FC-EPSO variants and other models. The root mean square error (RMSE) is also one of the datasets that has been calculated and assessed and adapted as an objective function by the proposed algorithm. To justify the superiority of the presented approach, it has been justified against other approaches presented in literature. The outcomes in [
21] have showed a least deviation between the estimated and measured curves with fastest convergence.
Integrating the computation and harris hawk optimization (HHO) algorithm is another approach that is presented in [
22] to determine the parameters of TDM regarding PV module. In this work, the authors utilized the standard test conditions (STC) datasheet values of PV modules with normal operating cell temperature (NOCT) to analytically examine four parameters while finding the remaining five parameters by relying on the HHO model. Seeking to estimate the parameters, two commercial PV panels have been used as monocrystalline CS6K280M and multi-crystal KC200GT. The results in [
22] has proved the efficacy of the presented model and by depending on the datasheet values only it can simply implement to find the electrical parameters of any commercial PV panel. In [
23] a new optimization method namely interval branch and bound algorithm is introduced and validated for three different parameter estimation models of PV cells (SDM, DDM and TDM). outcomes have been justified against other results in literature of the same data set. The behavior of the presented model is examined with regards to convergence speed and results in variability as comparison to metaheuristics. The estimated performance features of the tested cells for both P-V and I-V shown to be very similar to the experimental data and the obtained findings are really close to other efficient algorithms. In [
24], an improved wind driven optimization (IWDO) model is presented and applied to calculate triple-diode parameters of the PV cell model. In order to evaluate the proposed model, IWDO model has been implemented on three various PV model techniques, which are poly-crystalline, mono-crystalline, and thin- film. Accordingly, the obtained results have been compared with other findings collected from other contributions to validate its accuracy. According to results of [
24], the presented algorithm showed superiority over other models in terms of accuracy and convergence speed. The authors of [
25] have relied on manta ray foraging optimization (MRFO) to find the unknown parameters of PV cells. using MRFO is adapted to extract the optimal PV parameters of the single, double, and three-diode algorithms. Based on comparative results between different metaheuristic algorithms and MRFO, findings proved that MRFO has supported a better balance among experimental and calculated I–V curves. In [
26] an enhanced LSHADE optimization model called Chaotic LSHADE (CLSHADE) model which is traced to the Lambert W-function and has been presented to estimate TDM and DDM parameters of the PV equivalent circuits. The outcomes indicated that the accuracy of the CLSHADE model could be enhanced through adapting the presented solar cell current expressions where the RMSE is calculated based on them. For the purpose of investigating a complete photovoltaic algorithm, authors in [
27] have proposed an improved spherical evolution technique that is based on a novel dynamic sine-cosine mechanism (DSCSE). The experimental findings have indicated the superiority of DSCSE over other comparative approaches with different models and provided superior outcomes regardless different temperatures and light intensities. Based on the DE (HDE), a novel heterogeneous mechanism is presented in [
28] to identify PV model parameters. Parameter fitting for the DDM, SDM, STP6-120/36 MM, TDM, Photowatt-PWP201 MM, and STM6-40/36 MM were determined by HDE. The findings indicated the superiority of the HDE for majority of PV techniques. Moreover, the HDE also takes low execution time to conduct its task. Although the HDE showed necessary features, its behavior regarding few PV models like TDM and DDM can be further improved. In [
29], an enhanced model of the slime mould technique and based on Lambert W-function (ImSMA_LW) is proposed for extracting parameters of SDM, DDM, and TDM of PV module. According to [
29], ImSMA_LW offered compromised results under various scenarios with different conditions.
A combination of two metaheuristic algorithms is proposed for estimating the nine parameters of TDM in this research. The electromagnetism-like algorithm (EMA) used the attraction-repulsion concept to synergic the mutation strategy of conventional DE algorithm. The proposed metaheuristic is called differential evolution with integrated mutation per iteration algorithm (DEIMA). In DEIMA, both mutation strategies of EMA and DEA are applied in the same iteration. Furthermore, a new adaptive formula has proposed in this paper to realize adaptive mutation factor and crossover rate values of DEA’S mutation strategy. The adaptive technique in this formula is based on evolution of the fitness function. The proposed PV modeling method is validated by experimental I-V data for seven operation conditions. In addition, the results of the proposed DEIMA are evaluated through conducting a comparison with other related contributions in literature.
The manuscript is structured as follows; the introduction part is presented in section one. In section two, the model of triple diode PV module and the formulating of PV module parameter estimation process as optimization problem are discussed. The proposed DEIMA is discussed in section 3. Next, the evaluation criteria that utilized for evaluating results of DEIMA are presented in section 4. The results of the proposed DEIMA-based PV modeling method are presented, discussed, and evaluated in section 5. The conclusion of this contribution and suggestions for future work are drawn in section 6.
5. Results and Discussion
A multicrystaline Kyocera KC120-1 with 120Wp capacity PV module is used in this paper for testing the proposed modeling method. The specifications of the aforementioned PV module are tabulated in
Table 1.
Seven different operation conditions are used as experimental data to extract the parameters of PV module. These operation conditions are denoted by G1 to G7 and they are tabulated in
Table 2. The first and second columns of
Table 2 comprise the solar irradiance and cell temperature of various operation conditions. It is worth mentioning that each operation condition includes various length of experimental
I-V data points that explained in the fourth column of
Table 2. It should be noted that the weather conditions and operation conditions terms are interchangeably used through this paper.
A different evolution with integrated mutation per each iteration was adopted to estimate the unknown parameters of TDM. Since the dimension of PV-module optimization problem is 9, then the decision variables (
) are 9, and the number of individual solutions will be
[
33,
34]. The maximum number of iteration (
) for DEIMA and other methods that adopted for comparison issue is proposed 500 as a typical value that is based on several trial-and-error tests. According to many operations, the switching control parameter (
) founds 0.28 present as the best performance of DEIMA. In the meanwhile, the mutation factor and crossover rate of DEIMA are adaptive according to the proposed formula that discussed previously.
The search space range of nine parameters regarding TDM is based to literature. The photocurrent,
,
,, diode saturation currents (
), and diode ideality factors (
) are chosen to be [
1,
8] A, [0.1, 2] Ω, [100, 5000] Ω, [1E-12, 1E-5] A, and [
1,
2], respectively [
35].
The nine parameters of TDM PV module that estimated based on DEIMA are explained in
Table 3. Based on the estimated parameters and Newton-Raphson method, the
I-V and
P-V curves of TDM PV module under seven different operation conditions can be obtained as illustrated in
Figure 3 and
Figure 4, respectively. According to
Figure 3 and
Figure 4, it can be visually concluded that
I-V and
P-V curves obtained by DEIMA-based PV modeling method are closer to experimental ones. It is worth to mention that experimental
I-V and
P-V curves of PV module are irregular due to the error in
I-V generator that used in the field to collect the experimental data.
Figure 5 shows the evolution of objective function within the whole generation under seven operation conditions for DEIMA to calculate TDM parameters of PV-module. The presented DEIMA shows fast convergence and minimum objective function values for all operation conditions. It should be noted that the proposed modeling method based on DEIMA exhibits a stable objective function value at the first 20 iterations.
In order to prove the superiority of the proposed PV modeling method based on DEIMA, a fair comparison was done with other methods in literature. The penalty differential evolution algorithm (PDEA) [
36], the improved adaptive differential evolution algorithm (IADEA) [
37], electromagnetism-like algorithm (EMA) [
38], ImSMA_LW [
29], and ant lion optimizer with Lambert W function (ALO
_LW) [
39] were used as bench marks for comparison purposes to indicate the effectiveness of DEIMA. The experimental conditions including the size of population, maximum number of generations, and search space of decision variables of the whole aforementioned methods are the same for all methods to ensure fair comparisons. It should be noted that the mutation factor and crossover rate of DEIMA and IADEA are dynamically adaptive according to a formula. Meanwhile, the mutation factor and crossover rate of PDEA are chosen to be 0.5 and 1, respectively [
36].
Figure 6 shows the
of the proposed DEIMA and other compared algorithms under seven operation conditions. The proposed DEIMA offers the lowest
values under the whole operation conditions with average value around 0.06024. The ALO_LW, ImSMA_LW, IADEA, and EMA provided the second, third, fourth, and fifth low
values, respectively. While, the PDEA exhibited the worse
value as compared to other methods. The DEIMA presents the lowest
as compared to other methods with average
of 0.00518 over seven operation conditions as shown in
Figure 7. The PDEA is still have the worst
values over the whole operation conditions.
Figure 8 shows the coefficient of determination of various algorithms as bar chart. The proposed DEIMA also offers compromise
values, which are close to one over the seven operation conditions. The average
of DEIMA, ALO_LW, ImSMA_LW, IADEA, EMA, and PDEA are 0.9923, 0.994, 0.9935, 0.9915, 0.9914, and 0.9885, respectively.
The CPU-execution times of various algorithms are tabulated in
Table 4 over seven weather conditions. The average execution time of DEIMA is around 27.69 sec. The DEIMA needs less time to conduct execution as compared to other methods. Although the algorithms ALO_LW and ImSMA_LW offered promising results in many evaluation criteria, they need long execution time to candidate the TDM optimal parameters of the PV module.
Figure 9 shows the
deviation of each operation condition (
). The DEIMA offers the lowest
values in G1, G2, G4, and G7 operation conditions. The EMA shares the proposed DEIMA in G3, G5, and G6 weather conditions by offering the best
values. The small values of
prove the capability of the proposed method to candidate effective estimation for PV-module parameters. The
value can be computed for various methods by using
over seven operation conditions. The DEIMA presents 0.0426 as the lowest
value as compared to IADEA, ALO_LW, EMA, and PDEA with 0.04416, 0.0446, 0.04684, and 0.04937, respectively.
The last criterion used to compare the results of DEIMA with other algorithms is the average absolute error (
).
Figure 10 shows the
of the proposed DEIMA and other methods. Based on
Figure 10, DEIMA presents the lowest
over seven operation conditions. It is worth mentioning that the
is significantly increased when the operation conditions are changed from G1 to G7, because the number of
I-V points in data set is increased as it was stated in
Table 2.
Based on the aforementioned discussions, the radar diagram in
Figure 11 can be drawn by scoring each algorithm according to its performance in each criterion. It is noticed that the proposed DEIMA is claiming the first score among other methods over most of criteria. In the meanwhile, PDEA obtained the last score (6) in most of criteria, except for the CPU-execution time.