1. Introduction
The International Renewable Energy Agency (IRENA) reported that in 2022, growth in wind and solar power led to the highest annual increase in renewable generation capacity, together accounting for 90% of all net renewable additions in 2022 [
1]. Globally, all renewables increased renewable generation capacity by 295 GW (+9.6%), while Photo-Voltaic (PV) energy continued to lead capacity expansion, with a world increase of 192 GW (+22%) [
2]. The highest growth in installed capacity of solar energy was registered in China (+86.0 GW), the United States (+17.6 GW), India (+13.5 GW), Brazil (+9.9 GW), the Netherlands (+ 7.7 GW), Germany (+7.2 GW) and Japan (+4.6 GW) [
1,
2].
To study the energy production of a single solar module or a PV installation with many modules, it is advisable to have simulation models to allow estimation of the amount of energy that might be produced for different climate conditions and configurations of installation [
3]. Therefore, it is important to know the energy performance of PV modules, and to predict, through modeling and simulation, their response to possible operating scenarios [
4].
Crystalline silicon (c-Si) PV modules are currently the most widely commercialized [
5], these modules are composed of cells connected in series and parallel [
6]. Manufacturers provide in the datasheets the power, voltage and current values under Standard Test Conditions (STCs), defined by:
of cell temperature (
),
of irradiance (
G) and
of air mass (
) [
7,
8,
9]. However, this information is not sufficient to perform a simulation that delivers reliable predictions about the output power under different operating conditions. As an alternative to STC, the datasheets also provide Nominal Operating Conditions (NOC), defined by:
,
of ambient temperature (
), wind speed
and
, the latter is known as the Nominal Operating Condition Temperature (NOCT) [
10,
11]. However environmental conditions are never ideal, so more representative models of the PV modules are needed, including the unknown internal parameters that are not found in the datasheet.
In order to extract these internal parameters of c-Si PV cells, mathematical models based on the one-diode equivalent circuit (that ideally consists of a diode, resistors, and a current source) [
12], with its variants of two-diode and three-diode have considered [
13,
14,
15]. Two models for photovoltaic cell modeling are often used: the one-diode model and the two-diode model with five and seven internal parameters respectively [
16]. Using these models it is possible to obtain the characteristic current-voltage (V-I) curves, which are very important for monitoring, controlling and evaluating the performance of PV systems. The accuracy of the models depends on the number of internal parameters and the number of diodes [
12]. The methods for extraction of the internal parameters are complicated, due to the number of variables involved and the non-linear behaviour of the model equations [
17]. However, the MATLAB GUIDE can be used to calculate the internal parameters of the PV modules, in an intuitive, simple and transparent way for both the one-diode or two-diode models [
18].
The MATLAB’s Toolbox GUIDE has been used to model the cells and PV modules in many applications. Some researchers have developed an easy and simple Graphical User Interface (GUI) to create and modify PV device models and simulate the device operation in arbitrary conditions easily [
19], also to use for sizing on-grid [
20] and off-grid [
21] PV systems. This method uses mathematical models that represent the energy processing in PV, considering the different components such as solar generators, inverters, electrical cable connections and batteries [
22,
23,
24,
25]. Some authors have presented a GUI for continuous real-time monitoring of PV modules based on the V-I and V-P characteristics curves at different geographic sites. Typically, the GUI is integrated with LabVIEW software to allow monitoring of the variables [
26,
27]. Other authors have developed a GUI for educational purposes [
18,
28], allowing a user friendly, sequential interaction between the user (student) and the latent knowledge, the user can add information about the power generation capacity and energy requirement in a given rural or urban region. It also serves as educational support in electrical and/or mechanical engineering courses [
14]. It has also been demonstrated that students trained using the GUI tool easily can understand the concept of a PV solar module and their electrical parameters [
15].
A GUI has also been used for solar radiation forecasting, the calculation of incident radiation to the tilted module and the prediction of energy generated by the PV module [
29]. A neural network approach to the performance prediction of PV modules has also been considered. Here the feed-forward neural networks have been used to predict I-V curve parameters as a function of input irradiance and temperature [
30]. Other uses consider calculating arrays for partial shading conditions, using a generalized analytical approach to model the PV module [
31] and calculating the partial shading effects on PV arrays [
32]. These studies all use a GUI Toolbox for analyzing different factors such as atmospheric conditions and the configuration of PV modules and cells.
The aim of this paper is to demonstrate a Toolbox called PVMSim (PV + Matlab + Simulator), created in MATLAB’s GUIDE. This Toolbox allows the analysis of the electrical properties of silicon-based PV modules in a very intuitive way. Specifically, it determines the seven parameters of the two-diode model based on the information provided in the datasheet, using modeling algorithms established in the scientific literature. To prove the validity of the implemented GUI, the methods were applied to two PV modules with different power and technologies. The results were validated using the electrical parameters from the datasheet and the V-I curves obtained with the PVsyst® v7.3.1 software as reference.
This paper is organized as follows: in
Section 2, the two-diode equivalent model used for internal parameter extraction and the flowcharts of PVMSim blocks are explained.
Section 3, presents case studies of PV module modeling of mono-crystalline and multi-crystalline silicon technologies. In
Section 4 explains some advantages of the GUI and mathematical models. Finally,
Section 5 concludes with the main findings and contributions to the field of study.
4. Discussion
PVMSim is a MATLAB tool that offers a graphical interface that is easily integrated as a Toolbox. In addition, it allows the intuitive modeling and simulation of PV modules. It has the advantage that only the parameters from the datasheet are needed as input data, as well as a meteorological dataset (optional, if is desired to know the daily energy production and the effect of G and on the ). The Toolbox is useful for obtaining important data that can be used in more complex modeling, or as part of more comprehensive algorithms where the extraction of unknown internal parameters is included.
GUI’s Block 1 includes the data on the electrical parameters that are usually available in the datasheet provided by the manufacturer and can also be downloaded from the official website. These data are electrical data (
PmaxE, Voc, Vmpp, Impp, Isc, NOCT, η, Ki, Kv) and mechanical data (
length and
width). Some previous studies contemplate the use of other data, such as measurements of V-I curves [
40]. The principal advantage of this block is that all the data necessary for the extraction of unknown internal parameters are available and easily accessible to users.
GUI’s Block 2 introduces an algorithm for the extraction of internal parameters that uses the two-diode method, which has been validated for its robustness by several previous studies [
41,
48]. Also, this method is used as a reference to know the accuracy of new, complex and modern methods [
46,
71]. This block includes the Newton-Raphson iterative method, in order to obtain the V-I characteristic curve as close as possible to the curve of the STC of the datasheet, where the value of
reaches its minimum error below a tolerance
with respect to
provided by the manufacturer. Simulations have shown that this method is successful for high irradiance values (
to
), for lower values (below
) it is less accurate. These results are in agreement with other studies where similar data sets were obtained [
41]. This study considered mono-crystalline (HEE215MA68) and multi-crystalline (SW150polyR6A) silicon PV module models, but it has been shown that, in general, this method is very robust for modeling these technologies and also thin-film silicon [
42].
There are other methods for the extraction of internal parameters. Recent studies have used the one-diode method [
36,
72,
73] and three-diode [
74,
75]. However, this method was chosen because it is very efficient and accurate. In addition, it has been proven effective for a wide range of commercial silicon-based PV technologies [
42]. Currently and for the next 5 years, PV modules based on crystalline silicon technology will be the market leaders, representing almost 95% of world production [
76]. The algorithm used, iteratively calculates the maximum power point until the manufacturer’s
value is obtained, which considerably improves PV string design and sizing studies. Other studies consider the use of the one-diode model also serves the same purpose when precision is not important.
Due to the non-linearity of the model, the computational calculations are not straightforward. In order to improve the precision in the extraction of the unknown internal parameters, other methods can be used, such as optimization techniques and models based on artificial intelligence [
12,
17]. However, this takes more computational time.
In GUI’s Block 3, the results were compared with the PVsyst, demonstrating that the effect of G and on the PV modules are in the range of professional software simulations that are commonly used worldwide. The metrics are thus demonstrated, with low MAE errors. Users can simulate as many curves as desired to perform analysis, design and sizing of PV systems.
In GUI’s Block 4, the electrical parameters of the PV module are calculated and displayed in the plot, which also includes
and
, which are not provided by the manufacturer. This block is useful to find out the efficiency of a specific PV module for the conditions of the installation site. It allows performance for STC to be extrapolated to local performance for conditions anywhere in the world. This block could be of interest to researchers with a special interest in analyzing of
loss depending on the
for the industrial silicon solar cells [
77], limitations of
in heterojunction PV cells [
78], assessment the performances and the energy production under various values of
and
G as well as the correlation between the
and the weather condition [
79]. The Equation (
15) could be changed to another method that adds other meteorological parameters (i.e.,
,
G, wind speed and relative humidity) in order to improve the prediction of
and
, but would require prior experimental analysis at the PV installation site.
GUI’s Block 5 simulates the effect of
G and
on
,
and
throughout the chosen day. The results shown in the plots in
Figure 15 are only for during the hours of Sun. This block has the advantage of importing the weather data from a
file, which does not limit the source of the data. For this study, the NASA data source was used [
57], but users can import climate data measured
in situ. Using the tab as separator, the
file must be structured as follows:
1st column: date and time 01/01/2022 0:00:00
2nd column: irradiance value G ()
3th column: ambient temperature value ()
Santiago de Cuba (a province in the eastern region of Cuba considered as a study case), has a predominantly humid tropical climate. It is common for the PV modules to reach the operating values presented in
Figure 15 and then
decreases to less than 2% (
Figure 18). The results of this block are consistent with other experimental study in the same region of Cuba,
in situ measurements based, in which it was proved that for a six months study, the efficiency dropped to 1.9% during the day with the temperature in the range of
[
58].
PVMSim make MATLAB easy to use, eliminating the need of uses scripts or Simulink programming. There are other similar GUIs in MATLAB documented in previous studies, in which different characteristics of PV modules were analyzed, both in their intrinsic operation, as well as in real-time supervision, performance under certain operating conditions or technical-economic reliability [
18,
25,
26,
67]. It is also common to use other platforms such as Python that integrate with the MATLAB platform [
80,
81,
82]. The choice of one or another platform often depends on the knowledge and skill of the user.
With PVMSim is not possible to identify the PV module that best suit a specific PV project or a specific geographical area. Like other professional software such as PVsyst, SAM, HOMER, the user is responsible for choosing the PV module that best suits their design or sizing needs, and then modeling or simulating the operating conditions of the system’s location. The PV project under evaluation must previously define the PV module. For this reason, the user must study the market to determine the PV module that best suits their requirements.
Figure 1.
Equivalent circuit of a photovoltaic module (a) one-diode and (b) two-diode.
Figure 1.
Equivalent circuit of a photovoltaic module (a) one-diode and (b) two-diode.
Figure 2.
Typical (normalized) V-I and V-P characteristic curve of a PV cell.
Figure 2.
Typical (normalized) V-I and V-P characteristic curve of a PV cell.
Figure 3.
Typical structure of PV arrays.
Figure 3.
Typical structure of PV arrays.
Figure 4.
Typical (normalized) V-I characteristic curve of a PV cell and plot of by the gray rectangular area.
Figure 4.
Typical (normalized) V-I characteristic curve of a PV cell and plot of by the gray rectangular area.
Figure 5.
Main screen of the Toolbox PVMSim.
Figure 5.
Main screen of the Toolbox PVMSim.
Figure 6.
Algorithm for extraction of internal parameters (GUI’s Block 2 of PVMSim).
Figure 6.
Algorithm for extraction of internal parameters (GUI’s Block 2 of PVMSim).
Figure 7.
Algorithm for obtaining characteristic curves (GUI’s Block 3 of PVMSim).
Figure 7.
Algorithm for obtaining characteristic curves (GUI’s Block 3 of PVMSim).
Figure 8.
Algorithm for obtaining and plot and values (GUI’s Block 4 of PVMSim).
Figure 8.
Algorithm for obtaining and plot and values (GUI’s Block 4 of PVMSim).
Figure 9.
Algorithm for obtaining performance PV daily (GUI’s Block 5 of PVMSim).
Figure 9.
Algorithm for obtaining performance PV daily (GUI’s Block 5 of PVMSim).
Figure 10.
Curves obtained from GUI’s Block 2 of PVMSim. I-V and P-V characteristic curves obtained from the numerical compute of the and values: (a-d) HEE215MA68 and (e-h) SW150polyR6A.
Figure 10.
Curves obtained from GUI’s Block 2 of PVMSim. I-V and P-V characteristic curves obtained from the numerical compute of the and values: (a-d) HEE215MA68 and (e-h) SW150polyR6A.
Figure 11.
Curves obtained from GUI’s Block 3 of PVMSim. Plot of V-I and V-P curves for variable values of G and constant at . The circle marks represent the .
Figure 11.
Curves obtained from GUI’s Block 3 of PVMSim. Plot of V-I and V-P curves for variable values of G and constant at . The circle marks represent the .
Figure 12.
Curves obtained from GUI’s Block 3 of PVMSim. Plot of V-I and V-P curves for variable values of and constant at . The circle marks represent the .
Figure 12.
Curves obtained from GUI’s Block 3 of PVMSim. Plot of V-I and V-P curves for variable values of and constant at . The circle marks represent the .
Figure 13.
I-V curves including electrical parameters for STC, obtained from GUI’s Block 4 of PVMSim. represented by the rectangular area of gray color: (a) HEE215MA68 and (b) SW150polyR6A.
Figure 13.
I-V curves including electrical parameters for STC, obtained from GUI’s Block 4 of PVMSim. represented by the rectangular area of gray color: (a) HEE215MA68 and (b) SW150polyR6A.
Figure 14.
I-V curves including electrical parameters for NOC, obtained from GUI’s Block 4 of PVMSim. represented by the rectangular area of gray color: (a) HEE215MA68 and (b) SW150polyR6A.
Figure 14.
I-V curves including electrical parameters for NOC, obtained from GUI’s Block 4 of PVMSim. represented by the rectangular area of gray color: (a) HEE215MA68 and (b) SW150polyR6A.
Figure 15.
Evolution of G and during the chosen days: (a) March 21, (b) June 21, (c) September 21 and (d) December 21.
Figure 15.
Evolution of G and during the chosen days: (a) March 21, (b) June 21, (c) September 21 and (d) December 21.
Figure 16.
Curves obtained from GUI’s Block 5 of PVMSim. Evolution of the and daily energy output: (a-d) HEE215MA68 and (e-h) SW150polyR6A.
Figure 16.
Curves obtained from GUI’s Block 5 of PVMSim. Evolution of the and daily energy output: (a-d) HEE215MA68 and (e-h) SW150polyR6A.
Figure 17.
Curves obtained from GUI’s Block 5 of PVMSim. Variation of according to the evolution of G and : (a) HEE215MA68 and (b) SW150polyR6A.
Figure 17.
Curves obtained from GUI’s Block 5 of PVMSim. Variation of according to the evolution of G and : (a) HEE215MA68 and (b) SW150polyR6A.
Figure 18.
Curves obtained from GUI’s Block 5 of PVMSim. Linear fit of the vs : (a) HEE215MA68 and (b) SW150polyR6A.
Figure 18.
Curves obtained from GUI’s Block 5 of PVMSim. Linear fit of the vs : (a) HEE215MA68 and (b) SW150polyR6A.
Table 1.
Electric parameters extracted from datasheet of analyzed PV modules [
68,
69].
Table 1.
Electric parameters extracted from datasheet of analyzed PV modules [
68,
69].
|
HEE215MA68 |
SW150polyR6A |
Parameter |
STC |
NOC |
STC |
NOC |
|
250±3% |
183 |
150±2% |
110.1 |
|
37.40 |
34.5 |
22.5 |
20.5 |
|
30.3 |
27.7 |
18.3 |
16.6 |
|
8.72 |
7.25 |
8.81 |
7.17 |
|
8.22 |
6.7 |
8.27 |
6.62 |
|
-0.34 |
- |
-0.31 |
- |
|
- |
45 |
- |
46 |
Table 2.
Seven internal parameters of PV modules calculated with PVMSim.
Table 2.
Seven internal parameters of PV modules calculated with PVMSim.
No |
Parameter |
HEE215MA68 |
SW150polyR6A |
1 and 2 |
|
|
|
3 |
|
8.67 |
8.81 |
4 |
|
1 |
1 |
5 |
|
1.2 |
1.2 |
6 |
|
0.229 |
0.166 |
7 |
|
233.569 |
105.973 |
Table 3.
Metrics of the calculated electrical parameters by PVMSim at STC and NOC.
Table 3.
Metrics of the calculated electrical parameters by PVMSim at STC and NOC.
|
|
HEE215MA68 |
SW150polyR6A |
Condition |
Parameter |
Datasheet |
PVMSim |
MAE |
Datasheet |
PVMSim |
MAE |
|
|
250 |
250.01 |
0.01 |
150 |
150.1 |
0.1 |
STC |
|
37.4 |
37.4 |
0 |
22.5 |
22.5 |
0 |
|
|
8.72 |
8.66 |
0.06 |
8.81 |
8.8 |
0.01 |
|
|
183 |
183.47 |
0.47 |
110.1 |
110.27 |
0.17 |
NOC |
|
34.5 |
34.5 |
0 |
20.5 |
20.8 |
0.30 |
|
|
7.25 |
7.03 |
0.22 |
7.17 |
7.11 |
0.06 |
Table 4.
Metrics of the calculated at different values of G and .
Table 4.
Metrics of the calculated at different values of G and .
|
|
HEE215MA68 |
SW150polyR6A |
Condition |
Value |
PVsyst |
PVMSim |
MAE |
PVsyst |
PVMSim |
MAE |
|
|
48.35 |
45.40 |
2.95 |
29.13 |
27.00 |
2.13 |
|
|
99.08 |
96.69 |
2.39 |
59.74 |
58.09 |
1.65 |
|
|
149.76 |
148.21 |
1.55 |
90.30 |
89.17 |
1.13 |
|
|
199.88 |
199.39 |
0.49 |
120.50 |
119.89 |
0.61 |
|
|
249.10 |
250.01 |
0.91 |
150.10 |
150.10 |
0 |
|
|
264.81 |
264.60 |
0.21 |
159.89 |
158.56 |
1.36 |
|
|
249.10 |
250.01 |
0.91 |
150.10 |
150.10 |
0 |
|
|
232.76 |
235.13 |
2.37 |
140.02 |
141.52 |
1.50 |
|
|
215.86 |
219.98 |
4.12 |
129.67 |
132.85 |
3.18 |
|
|
198.41 |
204.56 |
6.15 |
119.07 |
124.08 |
5.01 |
Table 5.
Effect of and G on , and at peak solar hour (13:00 hours).
Table 5.
Effect of and G on , and at peak solar hour (13:00 hours).
PV Module |
Parameter |
21th March |
21th June |
21th Sept. |
21th Dec. |
HEE215MA68 |
|
998.7 |
710.3 |
602.7 |
639.5 |
|
|
28.4 |
29.5 |
28.2 |
25.8 |
|
|
59.61 |
51.7 |
47.03 |
45.78 |
|
|
182.51 |
141.28 |
124.08 |
132.06 |
|
|
16.25 |
16.44 |
16.52 |
16.55 |
SW150polyR6A |
|
998.7 |
710.3 |
602.7 |
639.5 |
|
|
28.4 |
29.5 |
28.2 |
25.8 |
|
|
60.86 |
52.58 |
47.79 |
46.58 |
|
|
110.13 |
85.33 |
74.9 |
79.66 |
|
|
14.74 |
14.83 |
14.88 |
14.89 |