Electrical behavior dataset of photovoltaic mini panels under indoor and outdoor conditions

Abstract

This dataset presents the electrical performance characteristics of 20 photovoltaic mini panels (ZW 86 × 82 Hi-tronic) tested under three conditions. Test 1: I-V curve acquisition in direct operation mode, Test 2: I-V dark curve measurement, and Test 3: I-V curve acquisition in both direct and reverse operation modes under partial shading conditions. Tests 1 and 3 were conducted in outdoor environmental conditions, capturing current, voltage, irradiance, and temperature. Key electrical parameters, including short-circuit current, open-circuit voltage, and output power, were calculated. Test 2 was performed indoors, where the current, voltage, and temperature were acquired. This dataset offers valuable insights into the real-world performance of photovoltaic systems and serves as a reference for researchers focused on modelling and parameter estimation of photovoltaic cells and arrays.

Specifications Table

Subject	Engineering & Materials science
Specific subject area	Electrical information and weather conditions from outdoor and indoor testing of solar PV mini panels.
Type of data	Raw data: Temperature, irradiance, mini panel current, and mini panel voltage (.mat format). Processed data: Temperature, irradiance, mini panel current, mini panel voltage, mini panel power, open circuit voltage Voc, short-circuit current Isc, and maximum power point Pmpp (.mat format); current-voltage curve and power-voltage curve (.SVG format).
Data collection	These data were acquired experimentally in the Electronics and Renewable Energy laboratory. Test 1: named as direct mode tests, were acquired on Jun 22, 2022, from 8:00 am to 1:00 pm in outdoor conditions. Here the data was taken at three different irradiations levels for each mini panel (Irr1, Irr2, and Irr3). Test 2: mini panels dark tests, were taken on Aug 28, 2023, from 11:00 to 01:00 pm in indoor conditions without irradiation in the front mini panel surface. Test 3: direct and reverse mode tests, with a 20 series mini panel array. The first step is to select a mini panel. Then, capture current and voltage information in the array and the selected mini panel terminals under three different conditions: without shading in the selected area. Testing Instruments: i) Twenty mini solar panels with reference ZW 86 × 82 (Hi-tronic). Measuring Instruments: i) An oscilloscope Tektronix MDO 3024 was used to acquire the electrical variables (voltage and mini panel current); the irradiation and the temperature were acquired with a Fluke FLK-IRR1-SOL solar irradiance meter. The voltage sweep was made by programming a BK precision 8514 electronic load. Software: The data processing was developed in Matlab.
Data source location	Institution: Institución Universitaria ITM. City: Medellín. Country: Colombia. Latitude and longitude: 6.244681, -75.552074.
Data accessibility	Repository name: Electrical Data Collection of a Set of Mini Panels in Indoor and Outdoor Environments Data identification number: 10.17632/sc3y5gks5d.1 Direct URL to data: https://data.mendeley.com/datasets/sc3y5gks5d/1
Related research article	None.

1. Value of The Data

• •This dataset captures the performance of photovoltaic mini panels under direct and reverse mode operation and in indoor and outdoor conditions, making it a valuable resource for PV system analysis.
• •It allows analysis of the difference in the behavior of mini panels from the same batch in the first and second quadrant operation.
• •It supports the development of more accurate models for photovoltaic cells and arrays by providing real-world data on key electrical parameters such as short-circuit current, open-circuit voltage, and output power.
• •The combination of outdoor and indoor test conditions allows for a comprehensive evaluation of PV panel behavior under different environmental influences.
• •Researchers can use this dataset for parameter estimation, fault detection, and performance optimization of photovoltaic systems.

2. Background

Photovoltaic (PV) manufacturers provide electrical specifications based on standard test conditions (STC: 1000 W/m², 25° C, AM 1.5). However, this information may not accurately represent real-world performance under varying environmental and operational conditions. Collecting experimental electrical data is crucial to evaluate photovoltaic systems beyond manufacturers' specifications. Additionally, analyzing PV cells or panels in direct and reverse operation provides valuable insights. Direct operation mode characterizes efficiency under normal conditions where the element delivers electrical power. In contrast, reverse operation, which occurs due to partial shading or the absence of bypass diodes, can lead to hot spots and accelerated degradation [1,2]. In most databases, electrical information in the first quadrant is common. However, information from the second quadrant that allows analyzing parameters of interest such as the breakdown voltage (Vbr) is usually not included. Measuring both modes enhances understanding of electrical and thermal effects on PV performance. With this dataset, the estimation of parameters of PV systems for electrical models can be improved, such as the Single Diode Model (SDM), Double Diode Model (DDM), and Bishop Model [[3], [4], [5]]. These models require accurate parameters to reproduce I-V curves, predict system behavior, and optimize PV performance. Experimental data acquisition enables more precise modeling, fault detection, and optimization of energy harvesting strategies. Ultimately, this information contributes to developing more reliable and efficient PV systems, supporting advancements in renewable energy integration

3. Data Description

The Database folder contains two subfolders: Raw Data and Processed Data. The Raw Data folder includes information directly obtained from the measurement equipment. The Processed Data folder includes information after processing in Matlab software was done. Each folder, Raw Data, and Processed Data are formed by Test 1, Test 2, and Test 3 (see Fig. 1).

Fig. 1.

Identification of folders in the database.

Test 1 corresponds to the data from the tests in direct mode (Q₁), in which the I-V curve was obtained for each mini panel under three different irradiation conditions. The name of the Matlab file that contains the information for each test was proposed as follows: MPn_Irrm.mat, where n represents the mini panel under analysis (1 to 20) and m the irradiation level (1 to 3). For example, if the data were taken in mini panel 5 with the first level of irradiation, then the file is called MP5_Irr1.mat).

Test 2 corresponds to the data from the I-V curve dark tests. The files are named MPn.mat where n represents the mini panel under analysis (1 to 20). In this test only one curve was taken for each mini panel.

Test 3 corresponds to the data from the mini panel array tests. A mini panel in the array is selected as a study case. Then, the scenarios are considered: first, when the selected mini panel is not affected by shadowing (NS), the second when the mini panel is affected by a shadow that corresponds to 50% of its area vertically (S1), and third when the mini panel is affected by a shadow that corresponds to 50% of its area horizontally (S2). The files are named MPn_NS.mat. Where n is the number of the mini panel selected that goes from 1 to 20, and the final part is related to the shadow condition: NS refers to scenario without shadowing, S1 refers to the shadow 1 (MPn_S1.mat), and S2 refers to the scenario with shadow 2 (MPn_S2.mat).

For the raw data, the .mat files corresponding to the direct mode test data (Test 1) contain the following data:

• •Vectors I and V, the mini panel current and voltage.
• •The weather conditions of temperature and irradiance measured (Irr, T).

The .mat files corresponding to the dark test data (Test 2) contain the following data:

• •Vectors I and V, the mini panel current and voltage.
• •The temperature measured (T).

The .mat files corresponding to the direct and inverse mode test data (Test 3) contain the following data:

• •Vectors I and V, the current, and mini panel voltage.
• •The vectors Ia and Va, the current, and array voltage.
• •The weather conditions of temperature and irradiance measured (Irr, T).

For the processed data, the .mat files corresponding to the direct mode test data (Test 1) contain the following data:

• •The vectors I, V, and P, are the current, voltage and mini panel power respectively.
• •The calculated values of short-circuit current Isc, the open circuit voltage Voc, and the maximum power point in terms of power, voltage and current (Pmpp, Impp, Vmpp).
• •The weather conditions of temperature and irradiance measured (Irr, T).

The .mat files corresponding to the dark test processed data (Test 2) contain the following data:

• •The vectors I, V, and P, the current, voltage and mini panel power respectively.
• •The temperature measured (T).

The .mat files corresponding to the direct and reverse test data (Test 3) contain the following data:

• •The vectors I, V, and P, the current, voltage and mini panel power respectively.
• •The calculated values for the mini panel of short-circuit current Isc, the open circuit voltage Voc.
• •The maximum power point in terms of power, voltage and current (Pmpp, Impp, Vmpp).
• •The vectors Ia, Va, and Pa, the current, voltage, and array power, respectively.
• •The calculated values for the array of short-circuit current Isca, the open circuit voltage Voca, and the maximum power point in terms of power, voltage and current (Pmppa, Imppa, Vmppa).
• •The weather conditions of temperature and irradiance measured (Irr, T).

4. Experimental Design, Materials and Methods

The experimental stage involves analyzing the behavior in the first and second quadrants of 20 mini-panels of the same technology branch. The first quadrant (Q₁) is called direct operation mode because the panel or cell delivers power. The second quadrant (Q₂) is named reverse operation mode because the element consumes power instead of producing it. Each mini panel contains 12 series-connected cells, as shown in (a). (b) presents the technical specifications given by the manufacturer, open circuit voltage Voc = 6V and short-circuit current Isc = 150mA.

The I-V curves of each mini panel were acquired individually to analyze the behavior in the first quadrant in outdoor conditions. This information is detailed in the section named Test 1. Subsequently, I-V dark curves were obtained in Test 2. For this test, it was essential to conduct the experiment indoors to prevent any radiation from affecting the surfaces of the mini panels. This information allows to further analyse the performance of the mini panels in direct operation mode.

Finally, in Test 3, a string of 20 mini panels was analysed under partial shading conditions. This test enabled the collection of data for both the first and second quadrants at the mini panel level. Details of this test are presented in the corresponding section (Test 3).

4.1. Test 1: First quadrant information (Q₁)

The I-V curves were acquired considering three different irradiation levels for each mini panel (Irr1, Irr2_,Irr3), using translucent materials that reduced the surface irradiation, as seen in Fig. 3 (a)–(c).

Fig. 3.

Experimental stage for different irradiance levels: (a) without shadowing,

(b) and (c), using two different translucent materials covering the whole mini panel surface.

Variables such as mini panel voltage and current, temperature, and irradiation were measured for each test. An oscilloscope Tektronix MDO 3024 was used to acquire electrical variables (voltage and current in mini panel terminals); the irradiation and the temperature were acquired with a Fluke FLK-IRR1-SOL solar irradiance meter (see Fig. 4). A BK precision 8514 electronic load was used as a tracer I-V curve, programming it in a sweeping voltage mode. Fig. 4 also presents how different radiation conditions were obtained using translucent materials covering the mini panel area.

Fig. 4.

Test 1: (a) without shadowing (Irr1), and (b) with a translucent shadow that reduces the incident surface irradiance (Irr2 and Irr3).

The oscilloscope saves the test data in a CSV format, enabling the data processing to draw the I-V curves using MATLAB. In the MATLAB software, the following steps were employed:

• •Import the CSV file with the name of the mini panel case study. This file has two columns: the first includes the mini panel voltage data (V), and the second the mini panel current (I). Each measurement is saved as an independent vector in a .mat file.
• •Each test includes the information to reconstruct several I-V curves at the same temperature- radiation point. For this reason, the second step is to cut the current and voltage vectors according to the positions that include all the information from an I-V curve.
• •The next step is to apply a smoothing function using local regression with weighted linear least squares and a second-degree polynomial model, with a span of the moving average equal to 0.1, to reduce the noise in the current variable. The Matlab function is named smooth, and the used method is loess (I1 = smooth(V,I,0.1,'loess')).
• •Then, all the repeated data are deleted, and some points of interest such as open circuit voltage (Voc), short-circuit current (Isc), and maximum power point (Pmpp, Vmpp and Impp) were calculated using the interp1 Matlab function.
• •The final curve is obtained by plotting V against I in which each mini panel behavior can be observed and analyzed in every situation or study case.

Fig. 5(a) shows the curves obtained for mini panel 5 after processing the data. This test was performed under the irradiation and temperature conditions presented in Table 1. In Fig. 5(b), the calculated power-voltage curve for mini panel five under the three different irradiation conditions. The data set contained in Test 1 includes the first quadrant information of voltage, current, and power for each mini panel, as well as the information on radiation and temperature of each set of data.

Fig. 5.

Electrical information from mini panel 5 obtained under three different irradiance conditions.

Table 1.

Test Conditions of temperature and irradiance for mini panel 5.

Test name	Test conditions		Calculated values
	T [°C]	Irr [W/m2]	Voc [V]	Isc [mA]	Pmpp [W]	Vmpp [V]	Impp [mA]
Irr1	40.6	1017	6.89	104.7	0.49	5.24	95
Irr2	40.4	534	6.19	26.4	0.12	5.08	26.4
Irr3	39.9	423	5.76	12.6	0.05	4.57	11.2

4.2. Test 2: I-V dark curves

To obtain the dark I-V curve it is necessary to make the connection shown in Fig. 6. The tests were carried out indoors. The mini panel was placed upside down to avoid the incidence irradiation.

Fig. 6.

Test scheme to obtain information for I-V dark curves: (a) schematic, and (b) real setup.

The measurement equipment used to acquire the I-V dark curves were a Digital Oscilloscope R&S RTE1204 for voltage and current measurement in the terminals of each mini panel, an infrared meter Raytek Raynger ST 60 to measure the superficial mini panel temperature, and a Dual-Channel A linear DC Regulated Power Supply MCH-305D-II, as a voltage source for the mini panel. The voltage increased from zero to near the open circuit voltage value in the manufacturer's datasheet. This connection generates a current flow in the opposite direction; the panel behaves as a load and consumes power. Fig. 7 presents the results from the dark test in the mini panel 5.

Fig. 7.

Electrical information for dark curves in mini panel 5: I–V curve.

4.3. Test 3: First and second quadrant information (Q₁ and Q₂)

To obtain the behavior not only in the first but the second quadrant of each mini panel, a series connection of 20 mini panels is proposed, as shown in Fig. 8. Next, a mini panel is selected (mini panel 20), and 50% of its area is shaded with a solid (not translucent) shadow. Fig. 9 and shows two different shading patterns named S1 and S2, which are obtained by shading the mini panel at 50% of the area horizontally (a) and vertically (b), respectively.

Fig. 8.

Test scheme to obtain information in Q₁ and Q₂: (a) schematic and (b) assembly.

Fig. 9.

Proposed shading scenarios: (a) Mini panel without shading (NS), (b) Representation of shading S1_, and (c) Representation of shading S2.

For each test, variables such as mini panel voltage and current, array voltage and current, temperature, and irradiation were measured. An oscilloscope Tektronix MDO 3024 with a differential voltage probe was used for the acquisition of the electrical variables from the array terminals and the selected mini panel (voltage and current). The irradiation level was acquired with a MACSolar meter, and finally, the temperature was obtained with an infrared meter ref Raytek Raynger ST 60 pro. The voltage sweep required for the acquisition of I-V curves was done by programming a BK Precision 8514 electronic load. Then, for each mini panel, there were taken three groups of data:

• •Voltage and current measurement in the mini panel, and in the array, without shading (NS).
• •Voltage and current in the mini panel and in the array measurements, using S1 shading.
• •Voltage and current in the mini panel and in the array measurements, using S2 shading.

A series connection of 20 mini panels was necessary to capture the I-V curves of the mini panels, as Fig. 8(a) shows. The next step is to connect the array with the electronic load and the oscilloscope; with this setup, it is possible to obtain the I-V data in the array terminals and in the terminals of the mini panel selected as a case of study; for example, as shown in Fig. 8(a) with the mini panel 20 as a case of study. The oscilloscope saves the test data in a CSV format, enabling the data processing to draw the I-V curves using MATLAB. In the MATLAB software, the following steps were employed:

• 1.Import the CSV file with the name of the mini panel case study. This file has four columns: the first includes the time, the second is the array voltage data (Va), the third is mini panel voltage (V), and the last one is the array current (Ia) which is the same for the mini panel (I) due to the series connection of the array. Each measurement is saved as an independent vector in a .mat file.
• 2.Each test includes the information to reconstruct three or four I-V curves. For this reason, the second step is to cut the current and voltage vectors according to the positions that include all the information from an I-V curve.
• 3.The next step is to apply the smooth Matlab function to reduce the noise in the information.
• 4.Then, all the repeated data were deleted, and some points of interest such as open circuit voltage (Voc), short-circuit current (Isc), and maximum power point (Pmpp, Vmpp and Impp) were calculated using the interp1 Matlab function.
• 5.The final curve is obtained with V vs. I, in which each mini panel behavior can be observed and analyzed in every situation or study case.

Fig. 10(a) and (b) present the results obtained for the mini panel 5. For Fig. 10(a), the black I-V curve represents the information of the unshaded array (NS). The red I-V curve represents the array of information when mini panel 5 is affected by shade S1, and the blue I-V curve is when the mini panel is affected by shade S₂. In the same way, Fig. 10(b) presents the mini panel 5 I-V curve in the first and second quadrants in the same conditions without shading (NS), with shade S1 and shade S2. Table 2 presents the weather conditions for Test 3 developed in mini panel 5. Figs 2, 11

Fig. 10.

Test information for mini panel 5: (a) I-V array curve, and (b) P-V array curve.

Table 2.

Condition of temperature and irradiance for mini panel 5 Test 3.

Test name	T [°C]	Irr [W/m2]
NS	61.2	948
S1	62	947
S2	54.2	920

Fig. 2.

Mini panel used for the experimental stage: (a) Front view, and (b) Rear view.

Fig. 11.

Test information for mini panel 5: (a) I-V mini panel curve, and (b) P-V mini panel curve.

Limitations

Not applicable.

Ethics Statement

The authors have read and followed the ethical requirements for publication in Data in Brief and confirm that the current work does not involve human subjects, animal experiments, or any data collected from social media platforms.

CRediT authorship contribution statement

Bonie Johana Restrepo-Cuestas: Conceptualization, Methodology, Writing – original draft, Data curation, Funding acquisition, Validation, Formal analysis, Investigation. Alejandra Ortiz-Pasos: Conceptualization, Methodology, Writing – original draft, Software, Formal analysis, Data curation, Funding acquisition, Investigation. Mariana Durango-Flórez: Writing – original draft, Investigation, Data curation, Writing – review & editing.

Data Availability

• Mendeley DataElectrical Data Collection of a Set of Mini Panels in Indoor and Outdoor Environments (Original data).