1 Introduction

The most important renewable energy source is solar power. Solar energy harvesting systems, such as rooftop water heating pipes, solar cells, and mirrors, are constantly improving and their efficiency grows with the advancement of technology [1].

Photovoltaic electricity from the sun it is a non-modern technology that is regarded the most effective and is the most widely utilized in solar energy technologies [2]. Solar photovoltaic energy is based on the use of sunlight without the use of heat. In the creation of energy, heat is a negative factor. The lesser the manufacturing efficiency, the higher the temperature of the unit. The ideal temperature for solar PV panel electricity production is 25 °C [3], while in some circumstances; high intensity radiation with a high degree affects the PV panel's efficiency [4]. Photovoltaic solar panels consist of many solar cells; these cells are made of semiconductors such as silicon, and are designed in two layers, a positive layer and a negative layer, which is what is known as the electric field [5].

The waves that are emitted by the sun stimulate the cell to make energy. When sunlight penetrates the solar cell, it generates a negative and positive voltage inside the p–n junction. Positive electrons travel to the top surface, while negative electrons travel to the lower surface. The two surfaces are connected to a battery to produce energy by drawing negative electrons. Photovoltaic cells are a promising technology and one of the most important alternative energy sources [6]. The major challenge for PV cell producers is the high temperature [7]. The Kingdom of Saudi Arabia is a hotbed of solar installations and is one of the renewable energy objectives outlined in Vision 2030 [8].

The top conduction layer, the absorbent layer, and the rear layer are the three primary layers in a solar cell. The cell also has two positive and negative electrical layers. The electrical contact layer (positive), also known as p-type [9]. This layer is located on the cell's face and is made up of a slice taken from silicon monocrystals with some impurities added to it, and the background electrical contact layer (negative), which is made up of pure silicon with some impurities added to it, and both layers work together to transfer electrical current to and from the cell (Fig. 1).

Fig. 1
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Solar cell compound

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There are three main common types of solar cells available in the market. Monocrystalline solar cells consist of a large mass of silicon and are produced in the form of a chip. Polycrystalline solar cells are made by melting multiple silicon crystals together, then re-merging them into one panel [11]. Polycrystalline solar cells are made by cutting silicon wafers for the ability to be attached to the solar panel [10]. Polycrystalline solar cells are made by melting multiple silicon crystals together, then re-merging them into one panel. The maximum current that can be delivered from the cell's edges is measured by shorting the cell’s terminals at maximum output [12], and the current output in the solar cell is dependent on the intensity of the light coming from the sun or another source, as well as the angle at which the light is projected. When there is no load in the cell at the time of measurement, the voltage can be measured across the ends of the cell, and the voltage changes from one cell to the next due to differing manufacturing procedures and temperatures. The highest limit of the electrical energy output (Pm) to the radiative energy input can be described as the efficiency of a solar cell (Pin) [13]. The efficiency of a system is measured in terms of its impact on the environment [14]. PV module manufacturers use standard test conditions to measure three primary components: cell temperature, radiation, and air mass. These circumstances vary and mostly affect the power output of the modules [15].

As a result, this work provides a study to improve the efficiency of solar cells by describing the capacity of the cell during the cell cycle and recording the cell's characterization, and then studying ways to improve this performance by adding a layer of copper sulfate that absorbs the sun's heat and allows only sunlight to pass through the cell.

2 Experimental work

2.1 Investigation methodology

To achieve the purpose of this work, a study was conducted the characteristics of the PV under the different climate conditions at site Mecca (Makkah). The PV panel was installed and oriented to the south at a 21.5° angle to match the site direction of Mecca (Makkah) City, producing the most power. The experiments carried out on the Solar Energy Lab., Mechanical Engineering Department. On several days in June, from 7:00 a.m. to 18:00 p.m., measurements of the ambient temperature, sun intensity, and relative humidity are taken and recorded every hour to track the variation throughout the day. The various measurements are then recorded in the manner prescribed. The output power calculated [7], where

$$P=I\times V.$$

The PV efficiency is determined as following:

$$\eta =\left[\frac{{P}_{out}}{{P}_{in}\times A}\right]\times 100.$$

Also, the PV fill factor is determined using following equation:

$$FF=\left[\frac{\left(I\times V\right)}{\left({V}_{os}\times {I}_{sc}\right)}\right]\times 100,$$

Where \({P}_{out}\): PV output power per (W), \(I\): PV output current per unit ampere (A), \(V\): PV output voltage per unit volt (V), \({P}_{in}\): Light input power (solar radiation) per unit (W/m2), \(A\): Solar cell area (m2), \({V}_{oc}\): PV open circuit voltage per unit volt (V), \({I}_{sc}\): PV short circuit current per unit ampere (A) (Fig. 2).

Fig. 2
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PV panel

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2.2 Materials

This investigation makes use of the following materials: 10 W resistance, wire connections, copper sulphate powder from SPECIALITY CHEMICALS CO “CuSO4⋅5H2O—M.W 249.68, Assay—not less than 99% maximum contaminant levels iron (Fe)—0.1%, chloride (CI) —0.005%, a plastic layer of size: 365 × 275 mm and thickness of 0.1 mm, distiller water, some rubber in various thicknesses (5, 10, 20 mm), and GP silicone acetic.

2.3 Measurements

The suggested PV's output voltage and current were measured with a digital multimeter (KEW 1011) with the following accuracy: 0.5% in volts and 1.2% in current. While the ambient temperature and relative humidity are monitored using a “Temperature/Humidity Meter (TM-183) with accuracy: + %C in temperature.” All temperature measurements were carried out on panel surface.

The Meteon Irradiance Meter Type (060501) “Sensor CM4” with an operational temperature range of − 40 °C to + 150 °C and measurement up to 4000 W/m2 is used to measure solar radiation.

3 Results and discussion

Many experiments have been carried out to investigate the characteristics of the PV cell in various weather circumstances such as ambient temperature, solar radiation, and relative humidity. In addition, the performance of the PV is improved employing substrate materials such as copper sulphate solution (CSS) at concentrations (1%) with and without a plastic layer. Furthermore, the upper surface of the PV is covered by a plastic layer without CSS, with the height from the upper surface changing from 0 to 5 mm, 10 mm, and 20 mm. The results presented here study the properties of the PV under various weather circumstances such as ambient temperature, solar radiation, and relative humidity. The results also indicate the performance of the PV employing various plastic layer and copper sulphate solution materials.

3.1 Effect of weather conditions during the daytime

The following results are acquired under various weather circumstances, including solar radiation, ambient temperature, and relative humidity, on the PV's behaviour. Figures 3, 4, 5, 6, 7 and 8 depict the change in solar radiation, ambient temperature, and relative humidity over time. On June 6, 9, 11, 15, 19, and 20, 2021. It is observed from the behaviour of solar radiation on different days that solar radiation has a low value at first and then steadily grows until it reaches its maximum value about 12:00 pm. These numbers also demonstrate that solar radiation has a value greater than 1000 W/m2 between 9:00 a.m. and 14:00 p.m., and a value greater than 800 W/m2 between 8:00 a.m. and 15:00 p.m., after which it gradually drops (Table 1).

Fig. 3
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Variation of ambient temperature, solar radiation and relative humidity during the day (9 June 2021)

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Fig. 4
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Variation of ambient temperature, solar radiation and relative humidity during the day (9 June 2021)

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Fig. 5
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Variation of ambient temperature, solar radiation and relative humidity during the day (11 June 2021)

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Fig. 6
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Variation of ambient temperature, solar radiation and relative humidity during the day (15 June 2021)

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Fig. 7
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Variation of ambient temperature, solar radiation and relative humidity during the day (19 June 2021)

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Fig. 8
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Variation of ambient temperature, solar radiation and relative humidity during the day (20 June 2021)

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Table 1 Values of ambient temperature, solar radiation and relative humidity
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3.2 Effect of air gap on the performance of photovoltaic

Two identical PV panels are employed, with one PV covered by a plastic layer on the upper surface at a spacing ranging from 5.10 to 20 mm. Figure 9 depicts the output power of two PVs without and with a 5 mm air gap during the daytime hours of 20 June 2021. This graph shows that the PV output power without surpassing (0.015–7.066 W) was 6.747 W at 12:00 pm. Figure 10 depicts solar radiation and efficiency of two PV without and with a 5 mm air gap, while Fig. 11 depicts ambient temperature, relative humidity, and efficiency of two PV without and with a 5 mm air gap during the day.

Fig. 9
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Output power of two PV without and with air gap 5 mm during the day

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Fig. 10
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Solar radiation and PV efficiency without and with air gap 5 mm during daytime

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Fig. 11
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Ambient temperature, relative humidity and PV efficiency without and with air gap 5 mm daytime

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Figure 12 depicts the output power of two PV without and with a 10 mm air gap during the daytime hours of June 19, 2021. We can see from this graph that the PV output power without reaching (0.016–7.169 W) was 6.751 W at 12:00 pm. Whereas Fig. 13 depicts solar radiation and the PV efficiency of two PV without and with a 10 mm air gap, Fig. 14 depicts ambient temperature, relative humidity, and the PV efficiency of two PV without and with a 10 mm air gap during the day.

Fig. 12
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Output power of two PV without and with air gap 5 mm during the day

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Fig. 13
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Solar radiation and PV efficiency without and with air gap 5 mm during daytime

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Fig. 14
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Ambient temperature, relative humidity and PV efficiency without and with air gap 5 mm daytime

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Figure 15 depicts the output power of two PVs without and with a 20 mm air gap during the day on June 15, 2021. This figure shows that the PV output power was 7.22 W at 12:00 pm till it reached (0.018–7.37 W). Figure 16 depicts solar radiation and efficiency of two PV without and with a 20 mm air gap, while Fig. 17 depicts ambient temperature, relative humidity, and the PV efficiency of two PV without and with a 20 mm air gap during the day.

Fig. 15
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Output power of two PV without and with air gap 5 mm during the day

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Fig. 16
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Solar radiation and PV efficiency without and with air gap 5 mm during daytime

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Fig. 17
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Ambient temperature, relative humidity and PV efficiency without and with air gap 5 mm daytime

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Table 2 explains the effect of an air gap (5, 10, 20 mm) on power and efficiency. The air gap reduces power and efficiency while protecting the PV from dust.

Table 2 Reduction in power and efficiency between with and without and with air gap
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3.3 Effect of adding copper sulphate solution

Two PV panels are utilized in this portion. The PV upper surface is covered by a plastic covering on one of the two cells, which is well pasted to avoid permeability, and the other is free. The two PV panels’ output power and efficiency, as well as solar radiation, ambient temperature, and relative humidity, are all measured. Following that, CSS was injected at a concentration of 1% and the same parameters were recorded as before. Figure 18 depicts the output power of two PV systems with and without a plastic coating during the day on June 6, 2021. This graph shows that the PV output power without a plastic coating climbs gradually until 9:00 a.m., after which the value of output power remains nearly constant until 13:30. At 12:00 p.m., it registered 6.93 W. During the day, Fig. 19 depicts the variation in solar radiation and efficiency of two PV systems without and with a plastic layer. Figure 20 depicts the variation of ambient temperature, relative humidity, and efficiency of two PV systems without and with a plastic layer over the course of a day.

Fig. 18
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Output power of two PV without and with plastic layer during daytime

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Fig. 19
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Solar radiation and PV efficiency without and with plastic layer during daytime

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Fig. 20
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Ambient temperature, relative humidity and PV efficiency without and with plastic layer during daytime

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Figure 21 depicts the output power of two PV systems without and with CSS 1 percent daylight during the hours of 9 June 2021. This graphic shows that the output power of free PV starts low and gradually grows as solar radiation increases until it reaches (0.019–7.61 W). At 12:00 p.m., it measured 7.46 W. Figure 22 depicts solar radiation and PV efficiency without and with 1% CSS during the day. Figure 23 depicts the ambient temperature, relative humidity, and efficiency of two PV systems with and without a 1% CSS and a layer of plastic during the day.

Fig. 21
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Output power of two PV without and with CSS 1% during daytime

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Fig. 22
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Solar radiation and PV efficiency without and with CSS 1% during daytime

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Fig. 23
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Ambient temperature, relative humidity and PV efficiency without and with CSS 1% during daytime

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Table 3 compares output power and PV efficiency without and with CSS and a layer of plastic at various concentrations.

Table 3 Reduction in output power and PV efficiency between without and with adding CSS and a layer of plastic at different concentration
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4 Conclusion

Photovoltaic (PV) energy is regarded as one of the most essential options. Renewable energy is free, clean, and available most of the time. The performance of solar cells is externally dependent on environmental conditions, with changes in ambient temperature and solar radiation affecting output parameters such as output voltage, current, power, efficiency, and fill factor. The current thesis portrayed Makkah city's climate parameters like as sun intensity, ambient temperature, and relative humidity on various days in June. This was done to investigate the features of the PV in various weather conditions. This study suggests that:

  1. 1.

    Solar radiation begins low and gradually increases until it reaches its peak at 12:00 p.m. between 9:00 a.m. and 14:00 p.m., solar radiation is greater than 1000 W/m2, and between 8:00 a.m. and 15:00 p.m., it gradually decreases.

  2. 2.

    2.The ambient temperature has initially small values of around (30–35 °C), then gradually increases to a high of more than 40 °C between 9:00 a.m. and 17:00 p.m., and then gradually lowers again to values of around (33–38 °C) at time 18:00 p.m.

  3. 3.

    Relative humidity has initially high values (24–39%) and then steadily drops until it reaches its minimal values (7–16%). The relative humidity drops as the temperature rises.

  4. 4.

    The PV output power reaches its peak between 9:30 a.m. and 1:30 p.m., and hence the output power drops as solar radiation increases.5. The maximum value of the PV efficiency at the period between 7:30 and 8:30 a.m. and then gradually decreases with increasing of the ambient temperature although increasing in solar radiation.

  5. 5.

    In Makkah, relative humidity has no effect on the performance of photovoltaic solar cells.

  6. 6.

    Air gaps (5, 10, 20 mm) generated by a plastic layer from the upper surface of the PV diminish the PV output power by 1.52 W, 1.44 W, and 1.62 W, respectively. Furthermore, it affects PV efficiency by 1.4%, 1.36%, and 1.48%, respectively. However, the air gap of 10 mm has the smallest drop in output power and efficiency.

  7. 7.

    The obtained results show that using a layer of plastic with a 1% concentration of copper sulphate solution (CSS) leads to a 2.55 W reduction in output power, while the efficiency of the PV with CSS concentrations continues to increase after 8:30 a.m. despite increasing ambient temperature, but CSS leads to a 2.47% reduction in efficiency at the peak time compared to the free PV.

5 Recommendations

Based on the findings, it is possible to recommend that the upper surface of the PV cell be covered with a layer of plastic at a height of 10 mm to protect it from dust and achieve the greatest performance.