Enhancing PV Module Efficiency Through Fins-and-Tubes Cooling: An Outdoor Malaysian Case Study

Abstract

One of the most important applications of solar energy is electricity generation using photovoltaic (PV) panels. Yet, as the temperature of PV modules rises, both their efficiency and service life decline. A common approach to mitigate this issue is cooling with fins, a design that is now widely adopted. However, traditional fin-based cooling systems often fail to deliver adequate performance in hot regions with strong solar radiation. In particular, passive cooling alone shows limited effectiveness under conditions of high ambient temperatures and intense sunlight, such as those typical in Malaysia. To address this limitation, hybrid cooling strategies, especially those integrating both air and water, have emerged as promising solutions for enhancing PV performance. In this study, an experimental and economic investigations were carried out on a PV cooling system combining copper tubes and aluminium fins, tested under Malaysian climatic conditions. The economic feasibility was evaluated using the Simple Payback Period (SPP) method. An outdoor test was conducted over four consecutive days (10–13 June 2024), comparing a conventional PV module with one fitted with the hybrid cooling system (active and passive). The cooled module achieved noticeable surface temperature reductions of 2.56 °C, 2.15 °C, 2.08 °C, and 2.58 °C across the four days. The system also delivered a peak power gain of 66.85 W, corresponding to a 2.82% efficiency improvement. Economic analysis showed that the system’s payback period is 4.52 years, with the total energy value increasing by USD 477.88, representing about a 2.81% improvement compared to the reference panel. In summary, the hybrid cooling method demonstrates clear advantages in lowering panel temperature, enhancing electrical output, and ensuring favorable economic performance.

1. Introduction

Renewable energy serves as an alternative to traditional power generation methods, encompassing sources like solar, wind, hydro, geothermal, wave, biomass, and hydrogen energy. These resources are naturally replenished within a short period, ensuring their sustainability [1]. Of all renewable options, solar energy stands out thanks to its many advantages, including the vast supply of clean energy available daily and the relatively low initial investment required for most solar energy conversion systems [2].

Due to the effectiveness aspect, the increase in temperature throughout the day can decrease PV panel efficiency. Therefore, the cooling method plays a crucial role in addressing this issue. The temperature of PV panels can be controlled using a variety of cooling methods, based on either passive or active processes. Convective, conductive, and radiative cooling are the three heat transport modes used to categorize these findings [3]. Researchers have explored various cooling strategies to lower the temperature of the PV module by removing the heat it generates. Active cooling requires additional parts, such as a pump or blower, to circulate the coolant flow [4]. Active water cooling is a primary direct method used in PV module cooling due to its direct coolant effect. To achieve practical electrical efficiency in a challenging environment, a well-designed cooling system can be mounted to the PV panel’s rear surface [5]. Copper tubes facilitate the flow of cooling water, enabling the panel to remove heat. A study investigated the performance of a serpentine half-tube for PV enhancement [6]. The use of a mathematical model was applied to examine the impacts of many parameters, including the type of tube, tube diameter, tube spacing, water inlet temperature, and flow velocity. Throughout these experiments, the researchers focused more on PV water cooling.

Conversely, previous studies on passive air-based cooling techniques have explored numerous design variations. For example, Ref. [4] investigated the use of truncated multi-level fin heat sink (MLFHS) configurations to enhance PV panel cooling through natural convection. Another experimental study at the National University of Malaysia assessed the performance of a PV module cooled with fins and a flat reflector [7]. This research compared two different heat sink types, longitudinal fins and lapped fins. Additional work looked into how the number and arrangement of fins affect PV panel cooling efficiency [8], finding that a setup with 26 staggered vertical fins delivered superior results in terms of energy efficiency and exergy performance. Furthermore, a study cited in Ref. [9] analyzed aluminum heat sinks with two fin orientations, one with standard straight fins and another with inclined sections, under typical working conditions, using computational fluid dynamics (CFD) simulations.

Researchers have also explored the use of combined cooling (passive + active), particularly with active water cooling and passive air cooling. A study to enhance a PV module’s electrical production was reported by combining passive and active cooling techniques [10]. An ultrasonic humidifier and an aluminum fin heat sink cooled the panel. The ultrasonic humidifier created a humid atmosphere at the back of the PV module. This study suggests using this cooling technique in hot, arid environments instead of solely relying on heat sinks, which have proven ineffective in extremely hot weather conditions [10]. Another study examined and identified two cooling methods: water and air cooling. In this case, three different PVs were tested, referred to as PV reference, PV with water cooling, and PV with fins mounted in the backside of the panel. This experiment showed a good cooling result [11].

2. Literature Review

2.1. Passive Air Cooling: Fin (Heat Sink)

Passive cooling refers to a broad category of PV cooling methods that operate without the need for additional energy sources. Pumps are unnecessary for passive cooling, which uses the natural flow of fluids (water or air) to cool solar panels. Its cooling capacity is, however, limited, as the surplus heat of the fluid must be regulated. Due to the buoyancy effect, hot and cold gases naturally exchange heat via convection. The air density diminishes as a panel heats up and elevates the temperature of the surrounding air. Consequently, warm air ascends, resulting in the formation of a natural convection current. Enhancing natural convection can be achieved by augmenting the heat-transfer area by the incorporation of fins [12].

A metal plate that absorbs and dissipates heat is referred to as a heat sink. Heat sinks may be utilized alongside forced or natural convection [13]. Heat from the PV array is dissipated by fins on a heat sink [14]. Fins augment the surface area of the heat sink, enabling it to absorb and dissipate greater amounts of heat. In warmer regions, PV arrays can advantageously utilize this cooling technique, as the increased surface area aids in maintaining their temperature and efficiency. Fins are essential components in numerous systems and devices designed to improve air or fluid flow.

Numerous studies on fin cooling techniques have been conducted recently. A study was conducted using the numerical evaluation of a truncated multi-level fin heat sink affixed beneath a PV module, considering the fin configuration. The study investigated the thermal efficacy through numerical modeling. The truncated MLFHS exhibits enhanced heat transfer performance due to its optimized surface geometry, surpassing that of the rectangular plate-fin heat sink. Their findings demonstrate that, relative to the conventional rectangular design, the truncated multi-level fin heat sink design yielded an average temperature reduction of 6.13% [4].

A study by Ref. [7] further explored the application of PV cooling systems through experimental work conducted at the National University of Malaysia. The investigation examined the synergistic effect of integrating both fin-based heat sinks and a planar reflector. Two distinct passive cooling configurations, longitudinal fins and lapping fins, were evaluated for their efficacy in thermal management. The experimental analysis was performed under specific environmental conditions, characterized by an average solar irradiance of 1000 W/m² and an ambient temperature of 33 °C. The findings indicated that the system utilizing lapping fins achieved optimal performance, resulting in a mean module temperature of 24.60 °C. This enhanced thermal regulation contributed to a superior electrical efficiency of 10.68% and a peak power output of 37.10 W.

The numerical evaluation of the thermal performance of various cooling methodologies designed for PV panels was performed. The systems under consideration include hollow fins and two distinct channel-based cooling configurations. A maximum temperature reduction of 2.50 °C was observed at the highest nanoparticle concentration. A comparative analysis of the different cooling systems revealed that the channel cooling configuration incorporating both a porous layer and wavy walls delivered the most superior performance. This system was followed, in descending order of efficacy, by the hollow fin and flat fin systems. The results further demonstrate that hollow fins offer a significant performance advantage over flat fins; employing 16 hollow fins resulted in an additional temperature reduction of 8.50 °C [15].

Table 1. Fin cooling methods.

Reference	Cooling Method	Temperature Reduction	Electrical Performance Improvement
[15]	Flat fin and hollow fin	8.50 °C	NA
[7]	Truncated fin	20.16 °C	9.20%
[9]	L-shaped aluminum fin	10.00 °C	4.00%
[16]	Lapping fin with reflectors	24.50 °C	13.70% (37.10 W)
[4]	Trapezoidal channel truncated multi-level fin heat sink (MLFHS)	6.13%	NA (Not Applicable)
[17]	Variation in fin heights and inclination angles	17.00 °C and 21.00 °C	11.34%
[18]	Fin cooling with container	6.10 °C.	5.30%
[19]	V-shaped fins	5.00 °C	11.60%
[20]	Evaporator with finned tube	10.00 °C	15.90%
[21]	Straight-finned heat sink	24.40 °C	1.08%

summarizes some of the studies of fin cooling methods.

2.2. Active Water Cooling

Active cooling is a predominant and widely utilized technology for PV cooling. This technology offers superior and more advanced heat dissipation compared to alternative ways. The advancement of this technique has diversified into several approaches for lowering PV temperature by water, including jet impingement, spray, pipes, thin films, microchannels, and combinations with other cooling technologies.

A study performed an indoor experiment to examine the efficacy of PV panels utilizing a water-cooling method. They employed a solar simulator that replicated sunlight using a halogen lamps. The use of this cooling system resulted in an increase in output power by 9–22% and a reduction in operating temperature by approximately 5 to 23 °C. Their proposed cooling technique led to an increase in panel efficiency. The lifespan was extended, and the payback period of the investment system was reduced [22].

The performance of a serpentine half-tube configuration for improving PV module output was studied in [6]. The results showed that this proposed design achieved approximately 10% higher thermal efficiency and around 6% greater electrical efficiency compared to conventional setups, translating to gains ranging from 3.60% to 5.50%. Using cooling tubes can boost power generation efficiency by over 13% while lowering PV panel temperatures by 10–25 °C. The effectiveness of these systems depends on the materials used and the tube design, whether full, half, or finned, and their arrangement in serpentine, linear, or circular patterns. Additionally, this method can be combined with various cooling techniques, including fluid-based options like air, water, and nanofluids, as well as integrating phase-change materials.

One study explored the structural design and parameter optimization of a PV cooling system by developing a thermal-electric integrated model. Using this model, the influence of various factors, including tube type, diameter, spacing, water inlet temperature, and flow rate, was assessed mathematically. The improved PV cooling setup significantly lowered the surface temperature, with tests showing a reduction of about 47 °C compared to a system without cooling. Results also demonstrated that the mass flow rate has an exponential relationship with both conversion and exergy efficiencies. The highest conversion efficiency (11.90%) and exergy efficiency (12.40%) were achieved at a mass flow rate of 0.04 kg/s. Similarly, when the water inlet temperature was set at 10 °C, peak conversion and exergy efficiencies reached 11.60% and 11.70%, respectively [23].

Table 2. Water cooling methods.

Reference	Cooling Method	Temperature Reduction	Electrical Performance Improvement
[24]	Spray water cooling and forced ventilation cooling	26.40 °C and 21.80 °C	14.30%
[25]	Water cooling	57.32 °C and 58.73 °C	11.50%
[26]	Nanofluid cooling	24%	12%
[27]	Nanofluid cooling	32.23%	12.75%
[28]	Water cooling	10%	9.70%
[29]	Jet cooling	34 °C	NA
[30]	Water cooling	9.40 °C	5.6% and 5.88%
[31]	Water cooling	N/A	0.35%
[32]	Water cooling	21 °C	11%
[33]	Water cooling	16 °C	1%

summarizes some of the studies of water cooling methods.

2.3. Combined PV Cooling

Combined cooling integrates active and passive cooling methods to improve the performance, longevity, and thermal efficiency of PV systems. For example, active methods with enhanced thermal recovery capabilities and rapid cooling can be combined with passive methods that exhibit slower cooling rates. Consider the fact that some cooling methods dissipate heat after extracting it from solar arrays, while others capture it. It is crucial to exercise extreme caution while integrating different strategies. The ideal situation entails integrating methods used just for cooling, devoid of any thermal processes, with those applied in the fabrication of PV panels [34].

A recent study employed mathematical modeling to evaluate and compare the performance of a phase-change material (PCM) system, a conventional cooling system, and a hybrid cooling setup combining a graphene–water nanofluid with PCM (RT-35HC). The experimental findings demonstrated that the PV module temperature decreased by approximately 23.90 °C when using the PVT (Photovoltaic Thermal)–PCM system with nanofluid, by 16.10 °C for the PV Thermal–PCM system with water, and by 11.90 °C for the standalone PV–PCM configuration. Additionally, when compared to PV modules without any cooling mechanism, the electrical efficiency improved by about 23.90% for the nanofluid-based PV Thermal–PCM system, 22.70% for the water-based system, and 9.10% for the PV–PCM system. The results further indicated that the hybrid PV Thermal–PCM system utilizing nanofluid achieved roughly 12% higher thermal efficiency than the PV Thermal–PCM system without nanofluid [35].

In specific regions, air precooling can markedly enhance the efficiency of PV thermal management owing to elevated ambient temperatures. Studies suggest that this problem can be mitigated through air precooling. Another study utilized a subsurface heat exchanger for air precooling. The experiment assessed various flow rates and elevated ambient air temperatures of 35, 40, and 45 °C to determine their impact on the module’s efficiency. The temperature was efficiently managed through the utilization of the heat exchanger [36].

Table 3. Studies related to PV combined cooling strategies.

Reference	Combined Cooling	Temperature Reduction	Electrical Performance
[37]	Water-cooled PV unit that is based on PCMs	NA	14.32%
[38]	Water and nanofluid cooling	15.26%	12.60%
[39]	Hybrid evaporative cooling	15 and 20 °C	11.20%
[40]	Fin and PCM cooling	4.70 °C	7.60%
[11]	Water and fins cooling	3 °C	7%
[41]	Micro fin and PCM cooling	10.7 °C and 12.5 °C	5.35% and 4.80%
[10]	Aluminum fins and ultrasonic humidifier cooling	14.61 °C	6.80%
[42]	Bi-fluid (air and water) module using Louver fins	19.20 °C	7.56%

summarizes some of the studies of combined PV cooling methods.

Previous studies have introduced various PV cooling mechanisms, including fin-based and tube-integrated systems, which have shown promising results under certain conditions. However, their effectiveness in environments with high ambient temperatures and intense solar irradiance remains uncertain. In this work, an evaluation of a previously reported configuration that combines U-shaped aluminum fins with circular copper tubes was performed [24]. The objective was to experimentally test the performance of this existing system under Malaysian climatic conditions, where high heat and solar exposure often limit PV efficiency.

The cooling system was mounted beneath the PV panel, following the original design approach, to enhance thermal dissipation and improve output stability. In addition to performance evaluation, an economic assessment was carried out using the Simple Payback Period (SPP) method, a standard tool for determining the cost-effectiveness of energy-related technologies. This analysis provides insights into the financial feasibility of applying the previously developed system in Malaysia, thereby confirming its practical relevance and limitations under real tropical conditions.

3. Materials and Methods

3.1. Description of PV with a Cooling System

The cooling system investigated in this experiment employs a combined approach that integrates fins and tubes to enhance heat dissipation from the PV module [24]. The fins provide passive air cooling by utilizing natural airflow, while the tubes facilitate forced active cooling through water circulation driven by a pump. Figure 1 illustrates the design concept of this combined PV cooling system. A vertical arrangement was selected to align with the natural airflow direction across the PV panel, promoting effective heat removal through the prevailing wind flow. At the rear side of the PV panel, ten aluminum fins, each measuring 88 cm in length and 48 cm in width, were installed. Collectively, the fins cover a total area of 4512 cm², which corresponds to about 70% of the panel’s rear surface. Copper tubes are integrated inside each fin and secured along the back of the panel.

The construction methodology for the combined PV cooling system begins with the preparation of ten 88 cm aluminum U-shaped fins (Figure 1 and Figure 2). These components are systematically attached to the rear surface of the PV panel using silicon-based adhesive, maintaining a uniform spacing of 2.40 cm. Particular attention is given to the adhesive application to ensure optimal thermal contact between the aluminum fins and the PV surface. Subsequently, copper tubes are positioned centrally within each fin channel to maximize thermal transfer efficiency. To enhance thermal conductivity, a layer of thermal grease is applied across all contact surfaces between the tubes and fins, followed by secure fastening using clips. The assembly process concludes with the interconnection of all ten fin–tube pairs and final attachment to the PV module’s rear surface using silicon adhesive. This meticulous fabrication approach ensures optimal heat dissipation characteristics while maintaining the structural integrity of the cooling system. The described configuration significantly improves the thermal management capabilities of PV modules under operational conditions [24].

3.2. Materials, Equipment and Experimental Setup

The outdoor experiment was conducted in the Solar Energy Research Institute, with coordinates of 2.9197° N, 101.7814° E., which is located at the National University of Malaysia (UKM). The specifications of the PV panel used in this experiment are shown in

Table 4. PV module specifications.

Description	Specification
Model	Rigid glass solar panel M120W
Cell type	SunPower cell, monocrystalline
Peak Power [Pmax]	120 Wp
Power Tolerance Range [%]	−3% to +3%
Max Power Voltage Vmp [V]	20.88 V
Max Power Current Imp [A]	5.75 A
Open Circuit Voltage Voc [V]	24.64 V
Short Circuit Current Isc [A]	6.21 A
Maximum System Voltage [VDC]	1000 VDC
Dimension [mm]	540 × 1190 × 35 mm
Operation Temperature [°C]	−40 to +85 °C
NOCT [°C]	45 ± 2 °C
Standard Test Condition (STC)	1000 W/m2, AM 1.5, and temperature of 25 °C

. The experiment set up was positioned to the north with a 5° elevation angle. The PV reference is a standard PV panel that is not equipped with any cooling system. This type of PV is involved in an experimental setup to be compared with a PV with a cooling system.

Table 5. Materials and equipment used for the outdoor experiment [43].

Materials and Equipment	Description	Specification
Monocrystalline PV panel	Convert sunlight radiation into electrical power.	The maximum power gain is 120 W
Fins	Rectangular shape and aluminum-based material.	10 units with dimension of each fin = 880 × 2.50 mm
Tubes	Working fluid flows through pipe to cool down the PV panel. The pipe is made of copper.	10 units with dimension of each pipe = 880 × 1.60 OD (Outer Diameter) mm
Silicon glue	To stick pipe and fins to the backside of panel.	2 tubes of transparent silicon glue
Thermal paste	To enhance heat transfer between tubes and fins.	5 tubes × 300 g
Hose	To connect water pump and copper tubes configuration.	Elastic transparent with 5 m of total length
Water pump	To give external force for water circulation.	Water flow 35 L/min
Solar meter	To measure solar irradiance of sun.	-TES 132 datalogging solar power meter -TES 1333R datalogging solar power meter
Thermocouple	To measure temperature value from the sensor.	24 channel Applent T4824
Water thermocouple	To measure temperature value from the sensor inside the water pipe or hose.	2 water thermocouples (AT4708 Multi-Channel)
Multimeter	To measure electrical output (voltage and current).	Digital Multimeter EM492
I-V checker	To plot the I-V curve from tested PV panel.	MP-11 Portable I-V checker
Data logger	To connect and read thermocouple output.	AT4824 Digital Temperature Data Recorder 24 Channels

details the materials and equipment required for this research. In general, materials are necessary for the experimental setup during the experiment, while equipment is used to measure the performance of the PV cooling. The description and specification of each material and equipment are shown in detail in Table 5. The experimental setup consists of a PV panel, direct sunlight, water tank, data logger, multimeter, data logger, and water pump. Figure 3 depicts this arrangement under Malaysian climatic conditions. The acquisition system installed in the outdoor experimental setup consists of a data logger, I-V checker, and laptop.

3.3. Temperature and Electrical Performance

The temperature difference equation calculates the difference in temperature between the cooling PV panel and the PV reference. The following formula is used to calculate the temperature difference:

$$∆T=T_{PV ref}-T_{PV cooling}$$

(1)

The primary indicators used to evaluate the impact of a cooling system on a PV module are output power and efficiency calculations. Output power, in particular, is determined by two key variables, voltage (V) and current (I), as expressed below:

$$P=V\times I$$

(2)

Here, P denotes the power output in watts, V is the voltage in volts, and I refers to the electric current in amperes. Once these values are determined, the electrical efficiency can also be calculated as shown below:

$${ \eta }_{el}={\displaystyle \frac{P_{max}}{GA}}$$

(3)

where G is the solar irradiance (W/m²) and A is the area of the PV (m²).

Electrical output measurement includes current (I), voltage (V), and power (P). Alligator clips connect the PV cables marked with (+) and (−) to the I-V checker. The results are taken for a certain time. The MP-11 Portable I-V Checker can automatically record the electrical output. This device can also connect to the PC to open the real-time data during the data collection.

The economic assessment employed the SPP (SPP) model to determine the cost-effectiveness of adopting the cooling system. The SPP offers a straightforward measure of how long it takes to recover the initial investment cost (C₀) [24], and it is defined as follows:

$$SPP={\displaystyle \frac{C_0}{Annual net cash flow}}$$

(4)

In this study, the initial investment is simplified by calculating the total cost of both the cooling system components and the PV panel. The annual net cash flow is then estimated by converting the electricity generated by the cooled PV system into monetary value using the applicable electricity tariff. Therefore, the equation can be expressed as follows:

$${SPP}_{PV with a cooler}={\displaystyle \frac{Total cost of a PV with a cooler}{Annual electricity price}}$$

(5)

Besides that, the SPP calculation is also able to make a projection across the lifespan of the PV panel by multiplication of the annual energy price and PV’s lifespan period in years (n), as in the following equation:

$$Projection=n\times Annual electricity price$$

(6)

3.4. Uncertainty Analysis and Accuracy

Experimental results can be affected by various sources of error and uncertainty, which may stem from the selection of instruments, their condition and calibration status, environmental conditions, measurement techniques, reading accuracy, and the overall experimental setup. In this study, key parameters such as temperature and solar irradiance were measured using properly calibrated and suitable sensors to ensure reliable data collection. Since all of the measurement tool are digitalized, the accuracy value of each measurement tool can be seen in

Table 6. The measurement tools’ accuracy.

Equipment	Parameters	Unit	Accuracy
Solar Power Meter TES 1333R	Solar intensity	W/m2	±5%
Solar Power Meter TES 132	Solar intensity	W/m2	±5%
UNI-T UT320D (2 channels)	Data logger for thermocouple	°C	±(0.5% + 1)
HT-9815 (4 channels)	Data logger for thermocouple	°C	±(0.5% + 2)
Applent T4824	Multi-channel temperature meter	°C	0.2% ± 2
Anbai AT4708	Multi-channel temperature meter	°C	0.2% + 1 °C
MP-11	Portable I-V checker	V & A	±1%
Digital Multimeter E-SUN EM492	Current and voltage	V & A	±0.1

.

Assessing the level of uncertainty associated with measurements, known as uncertainty analysis or error analysis, is an essential part of experimental work. Providing an estimate of uncertainty or a confidence interval alongside the results enhances the credibility of the data by indicating how dependable the measured values are.

Including uncertainty estimates with experimental results not only increases the transparency of the study but also enables meaningful comparisons with other research and theoretical models, thereby reinforcing the validity and reproducibility of the findings.

Factors such as instrument quality, calibration, environmental effects, and observation practices can all introduce measurement uncertainties. In this experiment, the ambient conditions, module temperature, water temperature, and solar radiation were all monitored using appropriate instruments to minimize such errors. Conducting a thorough uncertainty analysis is a valuable practice, particularly during experiment planning and design phases, as it helps identify and reduce potential sources of error. The uncertainty in a result (R), which is a function of independent variables, can be calculated based on the uncertainties in each variable. If the uncertainties in the independent variables X₁, X₂, …, X_n are represented by W₁, W₂, …, W_n, respectively, then the overall uncertainty in the result (W_r) can be determined accordingly, assuming an equal probability distribution for each variable’s uncertainty.

$$W_R={\left[{\left({\displaystyle \frac{\partial R}{\partial X_1}}{W}_1\right)}^2+{\left({\displaystyle \frac{\partial R}{\partial X_2}}{W}_2\right)}^2+\cdots +{\left({\displaystyle \frac{\partial R}{\partial X_n}}{W}_n\right)}^2\right]}^{1/2}$$

(7)

This study classifies the uncertainty parameters into three categories: temperature aspect, solar irradiance aspect, and electric output aspect. The uncertainty measurements for the temperature aspect are PV panel surface temperature (W_Ts), water inlet temperature (W_Ti), water outlet temperature (W_To), and ambient temperature (W_Ta). Since all of W_{digital thermocouple} and W_reading for all temperature types are the same, the total uncertainty in the measurement is evaluated based on the following calculation:

$$\begin{gathered} W_{Ts}=W_{Ta} \\ ={\left[{\left(W_{\mathrm{digital}\mathrm{thermocouple}}\right)}^2{+\left(W_{reading}\right)}^2\right]}^{1/2} \\ ={\left[{\left(0.1\right)}^2{+\left(0.1\right)}^2\right]}^{1/2} \\ =0.14 \end{gathered}$$

For water inlet and outlet temperature:

$$\begin{gathered} W_{Ti}=W_{To} \\ ={\left[{\left(W_{\mathrm{digital}\mathrm{thermocouple}}\right)}^2{+\left(W_{reading}\right)}^2\right]}^{1/2} \\ ={\left[{\left(0.005\right)}^2{+\left(0.1\right)}^2\right]}^{1/2} \\ =0.111 \end{gathered}$$

Table 7. Uncertainty parameters.

Uncertainty Parameter	Unit	Outdoor Experiment
PV panel surface temperature (WTs)	°C	±0.10
Water inlet temperature (WTi)	°C	±0.10
Water outlet temperature (WTo)	°C	±0.10
Ambient temperature (WTa)	°C	±0.10
Solar irradiance (WSi)	W/m2	±0.11
Current (WC)	A	±0.10
Voltage (WV)	V	±0.10

displays the overall uncertainty of the measured and computed experimental parameters during both indoor and outdoor experiments. All of the uncertainties were found to be within an adequate range. Hence, the uncertainty and error from the measurement tools are very small and provide a precise result.

4. Results and Discussions

4.1. PV Surface Temperature Results

Solar irradiance represents a key operational parameter in this study, as it directly influences the surface temperature of PV modules. Measurements taken over four consecutive days revealed a consistent diurnal pattern characterized by a single pronounced peak. Irradiance values were lowest during early morning and late afternoon, averaging 300–400 W/m² between 09:00–10:00 and 16:00–17:00, while transitional ranges were observed between 10:00–11:00 and 15:00–16:00. The peak period occurred steadily from 11:00 to 15:00, with irradiance reaching 700–800 W/m². Across 10–13 June 2024, the minimum values (300 W/m² on 10–11 June and 400 W/m² on 12–13 June) were recorded at the start and end of the solar cycle, whereas the maximum value (800 W/m²) consistently appeared between 12:00 and 14:00. Mean daily irradiance was calculated as 644.27, 635.27, 688.33, and 610.41 W/m² for the respective days, indicating stable solar resource availability during the experimental period.

PV surface temperature is an equally critical factor, given its inverse relationship with module efficiency—commonly expressed as a 0.40–0.50% reduction per °C increase in crystalline silicon systems. Accurate monitoring of surface temperature is therefore essential in evaluating the effectiveness of cooling interventions. For this purpose, five thermocouples were installed on both a reference module and a module integrated with the hybrid cooling system, alongside a sensor for ambient air temperature. The resulting profiles (Figure 4, Figure 5, Figure 6 and Figure 7) clearly show that the cooled module maintained consistently lower surface temperatures compared to the reference, particularly during midday peaks. Both modules followed the expected thermal response to solar intensity, with temperatures rising until 14:00 and gradually decreasing afterward as irradiance declined and convective cooling intensified. Notably, the cooling system effectively suppressed peak temperature excursions during maximum irradiance, helping sustain conditions closer to the module’s rated efficiency.

The data from 10–13 June further confirm this performance advantage. Maximum surface temperatures for the reference module (T_refavg) ranged from 57.97 °C to 62.03 °C, while the cooled module peaked (T_combavg) between 53.70 °C and 58.20 °C. This reduction is significant, especially considering the relatively stable ambient temperature (_Tamb), averaging around 31 °C. Analysis of daily averages highlights the same trend: the reference module registered 49.02–52.37 °C, while the cooled module maintained 46.43–50.23 °C. This corresponds to reductions of 2.08–2.58 °C, yielding relative efficiency improvements of 4.25–5.57%. The highest gain (5.57%) was recorded on June 13 under a mean irradiance of 610.41 W/m².

These reductions are practically meaningful, as they enhance electrical output, slow down thermally induced degradation, and improve overall system reliability. The findings demonstrate that the implemented cooling technique effectively alleviates the adverse effects of elevated operating temperatures, making it highly suitable for applications in high-irradiance regions.

4.2. PV Power Results

The power output of a PV system is directly influenced by both the voltage and current generated by the module, both of which are strongly affected by surface temperature and solar irradiance. Figure 8, Figure 9, Figure 10 and Figure 11 illustrate the power output results for the two PV panels tested during the outdoor experiment.

From the power output perspective, the highest values were recorded around midday when solar irradiance reaches its peak. In contrast, the electrical efficiency tends to be highest during the early morning and late afternoon when solar irradiance levels are lower. This is due to the well-known fact that higher module temperatures under strong solar radiation reduce the voltage output, lowering conversion efficiency despite high power generation. The results show that both the power output and electrical efficiency reached their maximum values on 12 June 2024, demonstrating the combined cooling system’s ability to enhance performance under real outdoor conditions.

To further evaluate the power improvement, the average daily power output was calculated. For the reference PV module, the average daily power outputs (P_ref) were 62.04 W, 59.64 W, 65.02 W, and 59.19 W, respectively. When the combined PV cooling system was applied, the averages for P_comb increased to 63.02 W, 61.15 W, 66.85 W, and 60.54 W over the same period. The greatest power increment, 1.83 W, was observed on 12 June 2024, corresponding to a 2.82% improvement compared to the reference PV. Notably, this also coincided with the highest average solar irradiance measured during the study period, 688.33 W/m², highlighting the significant impact of irradiance on power output.

For the electrical efficiency, the combined PV cooling system achieved its highest daily average on 12 June 2024, with η_elcomb of 23.78%, compared to 22.98% for the reference module (η_elref). This result confirms that an effective cooling strategy can reduce the adverse thermal impact on the PV module, allowing it to maintain higher operating voltages and improve efficiency. However, it is important to note that while higher solar irradiance generally increases power output, it does not linearly increase electrical efficiency. According to fundamental PV operation principles, electrical efficiency is inversely proportional to module temperature, which itself rises with increased irradiance. Therefore, cooling techniques play an essential role in minimizing temperature-induced efficiency losses while allowing the PV module to benefit from high irradiance conditions.

4.3. The Economic Aspect Using Simlpe Payback Period (SPP)

The SPP calculation is a fundamental economic assessment used to estimate the time required for an investment to recover its initial capital cost through annual savings or revenue, in this case, from the electricity generated by the PV system. Two key parameters in the SPP calculation are needed which are the total initial cost and the annual value of generated energy. The initial cost encompasses all capital expenditures associated with the system, including the cost of the PV panels and the additional cooling system. Meanwhile, the price of the annual energy output represents the monetary value of the electricity generated, which directly contributes to the return on investment.

Table 8. SPP calculation for combined PV cooling.

Description	Value	Unit
PV panel cost	58.50	USD
Combined cooling system cost	24.91	USD
Power generation	66.85	W
Effective hours in a day	10	h
Annual increased energy	244	kWh/year
Annual electric price	17.50	USD
Total cost for combined PV cooling	85.10	USD
SPP	4.52	Year

provides a detailed breakdown of the SPP calculation for the combined PV cooling system.

For the PV with the combined cooling system, the total initial cost, comprising both the PV panel and cooling components, is USD 85.10. The system achieves an annual energy yield of 244 kWh/year, resulting in an estimated annual electricity revenue of USD 17.50. Based on these figures, the calculated SPP for the combined PV cooling system is 4.52 years. This payback period indicates the short-term timeframe required for the investment to reach a breakeven point under current operating conditions.

A comprehensive understanding of the SPP (SPP) is fundamental for evaluating the long-term economic viability and investment returns of PV systems. To this end, Figure 12 presents a projection of the cumulative revenue growth across the system’s assumed 25-year operational PV lifespan. The graphical analysis reveals a progressively widening disparity in cumulative revenue between the two configurations over time. This divergence is directly attributable to the enhanced energy yield facilitated by the superior thermal regulation of the cooled system. The projection concludes that, the reference system attains a cumulative financial gain of USD 464.76. In comparison, the system integrated with the combined cooling technology achieves a significantly higher cumulative revenue of USD 477.88. This results in a net financial advantage of USD 11.43 for the PV cooling system, equating to a measurable performance increase of approximately 2.81% over the PV reference. This differential underscores the critical impact of thermal management on long-term economic returns. Nonetheless, the analysis demonstrates that integrating a cooling system can enhance both the technical and economic performance of PV installations, providing a viable pathway to maximize return on investment in regions with high ambient temperatures and solar irradiance levels.

4.4. Limitations and Future Work

This study, while providing valuable insights into the performance of a PV module equipped with a fins-and-tubes cooling system, has certain limitations. First, maintenance costs were not considered in the economic analysis. Although the system is largely passive, the circulation pump represents a moving component that may require periodic servicing or replacement throughout its lifespan. Excluding this factor simplifies the baseline evaluation but may slightly underestimate the total life-cycle cost. Second, the results are specific to Malaysian tropical climatic conditions and may not be directly generalizable to regions with different solar irradiance levels, ambient temperatures, or humidity. Finally, the experiments were carried out on individual PV modules, and scaling the cooling system to larger PV arrays may introduce additional hydraulic challenges, cost implications, and performance variations not captured in this study.

Future research should therefore aim to address these limitations. A comprehensive life-cycle cost analysis that includes pump maintenance and replacement schedules will provide a more complete picture of the system’s economic viability. Further optimization of fin geometry, tube arrangement, and pump operation could enhance cooling efficiency while minimizing parasitic energy consumption. Large-scale studies involving PV arrays or building-integrated PV systems would help determine the scalability of this approach. Comparative evaluations with other passive and active cooling methods under similar conditions would further establish the competitiveness of the fins-and-tubes design. Finally, integrating environmental impact assessments, including water usage, material life-cycle, and potential carbon reduction, would offer broader insights into the sustainability benefits of this cooling strategy.

5. Conclusions

This study examined the outdoor performance of a photovoltaic module integrated with a fins-and-tubes cooling system under Malaysian climatic conditions. The results demonstrated that the cooled module consistently achieved lower surface temperatures than the uncooled reference. On 13 June 2024, the final day of measurement, the reference module recorded a peak surface temperature of 58.67 °C, whereas the cooled module reached only 53.70 °C, showing a reduction of 4.97 °C. Across the four-day measurement period, the daily average temperature reductions ranged from 2.08 °C to 2.58 °C, corresponding to efficiency-related improvements of up to 5.57%. These outcomes highlight the system’s capability to mitigate temperature rise under strong solar irradiance and maintain PV operation closer to its rated efficiency.

The cooling effect translated directly into electrical performance gains. The cooled module consistently delivered higher average daily power output compared to the reference, with the largest increment of 1.83 W (equivalent to 2.82%) recorded on 12 June 2024, coinciding with the highest average irradiance of 688.33 W/m². This confirms that reducing module operating temperature sustains higher voltage levels and improves energy yield, especially during peak irradiance hours. Furthermore, the economic feasibility analysis showed a payback period of 4.52 years, indicating that the additional investment in the cooling system can be recovered within a practical timeframe, making it a cost-effective solution for PV enhancement in high-irradiance regions.

Despite these promising results, certain limitations must be acknowledged. The economic analysis did not include the maintenance and replacement costs of the circulation pump, which represents the system’s primary moving component. Additionally, the experimental duration was limited to four consecutive days and did not account for seasonal variability, long-term reliability, or degradation effects. The study was also confined to a single climatic location and conducted on individual PV modules, meaning that scaling up to larger arrays may present additional hydraulic, thermal, and economic challenges.

Future work should therefore extend testing over longer periods and across multiple seasons to assess performance stability under diverse conditions. Incorporating a full life-cycle cost analysis, including pump maintenance, will strengthen the economic evaluation. System optimization through fin geometry refinement, tube configuration adjustments, and pump operation strategies could further improve efficiency. Large-scale and comparative studies against alternative cooling methods are also recommended, together with environmental impact assessments covering water usage, material sustainability, and long-term CO₂ reduction potential.

Overall, this research confirms the applicability and cost-effectiveness of fins-and-tubes cooling for PV modules, while providing a foundation for future improvements and large-scale deployment.