In recent years, the global energy crisis and environmental degradation have intensified the urgency to develop renewable energy sources. Solar power, particularly through photovoltaic systems, has emerged as a pivotal solution due to its sustainability and scalability. Large-scale solar panel installations in desert and戈壁 regions are increasingly common, leveraging abundant sunlight and vast land availability. However, the performance of solar panels is significantly influenced by multiple environmental factors, including solar irradiance, ambient temperature, wind speed, and dust deposition. These factors can alter the electrical output and efficiency of solar panels, necessitating comprehensive studies to optimize their operation in harsh environments. In this work, we employ numerical simulations to analyze the impact of these variables on solar panel output characteristics, using field data to refine predictive models and enhance understanding of real-world behavior.
We begin by establishing a geometric and electrical model for solar panels based on equivalent circuit theory. The single-diode model is widely adopted for its balance between accuracy and simplicity, representing the solar cell as a current source in parallel with a diode, series resistance, and shunt resistance. The output current-voltage relationship is given by:
$$I = I_{ph} – I_0 \left[ \exp\left( \frac{q(U + I R_S)}{N_s n k T} \right) – 1 \right] – \frac{U + I R_S}{R_{sh}}$$
where ( I ) is the output current, ( I_{ph} ) is the photogenerated current, ( I_0 ) is the reverse saturation current, ( q ) is the electron charge, ( U ) is the output voltage, ( R_S ) is the series resistance, ( N_s ) is the number of series-connected cells, ( n ) is the ideality factor, ( k ) is Boltzmann’s constant, ( T ) is the absolute temperature of the solar panel, and ( R_{sh} ) is the shunt resistance. The photogenerated current depends on irradiance and temperature:
$$I_{ph} = [I_{sc} + K_i \times (T – 298)] \times \frac{G}{1000}$$
Here, ( I_{sc} ) is the short-circuit current under standard test conditions (STC: 1000 W/m² irradiance, 25°C), ( K_i ) is the temperature coefficient of ( I_{sc} ), and ( G ) is the actual irradiance received by the solar panels. The reverse saturation current is derived as:
$$I_0 = I_{rs} \times \left( \frac{T}{T_n} \right)^3 \times \exp\left[ \left( \frac{1}{T_n} – \frac{1}{T} \right) \frac{q E_{g0}}{n k} \right]$$
with ( I_{rs} = I_{sc} / \left[ \exp\left( \frac{q U_{oc}}{N_s n k T} \right) – 1 \right] ), where ( U_{oc} ) is the open-circuit voltage under STC, ( T_n = 298 \, \text{K} ), and ( E_{g0} = 1.1 \, \text{eV} ) for silicon.
The actual temperature of solar panels is critical for accurate performance prediction. Using field data from desert-based photovoltaic plants, we developed empirical models for solar panel temperature that account for ambient temperature, irradiance, wind speed, and dust effects. For spring, summer, and autumn, the temperature model is:
$$T = 9.6062 + 0.8761 \times T_{\text{ambient}} + 0.026 \times G_0 – 2.0425 \times V$$
For winter conditions, the model adjusts to:
$$T = 2.1572 + 1.0258 \times T_{\text{ambient}} + 0.0391 \times G_0 + 2.254 \times V$$
where ( T_{\text{ambient}} ) is the ambient temperature in °C, ( G_0 ) is the incident solar irradiance in W/m², and ( V ) is the wind speed in m/s. Dust deposition on solar panels reduces transparency, thereby decreasing the effective irradiance. The actual irradiance ( G ) is modified as:
$$G = G_0 \times \beta$$
where ( \beta ) is the transmittance of the dust-covered glass, ranging from 0 to 1. These equations are integrated into a MATLAB/Simulink environment to simulate the output characteristics of solar panels under varying conditions. The simulation model computes current-voltage (I-U) and power-voltage (P-U) curves, enabling analysis of key parameters like short-circuit current, open-circuit voltage, and maximum power point.
Solar irradiance is a primary driver of solar panel performance. To investigate its impact, we simulated scenarios with irradiance levels of 400 W/m², 600 W/m², 800 W/m², and 1000 W/m², while holding other parameters constant: ambient temperature at 25°C, wind speed at 3 m/s, and glass transmittance at 0.45 to represent dust accumulation. The results, summarized in Table 1, show that irradiance significantly affects the short-circuit current (( I_{sc} )) but has minimal influence on the open-circuit voltage (( U_{oc} )). As irradiance increases, ( I_{sc} ) rises proportionally, leading to higher maximum output power (( P_{\text{max}} )). This is because higher irradiance enhances photon absorption, generating more electron-hole pairs and thus increasing current. The relationship between irradiance and power is nearly linear, underscoring the importance of maximizing light capture in solar panel installations. However, in dusty environments, the effective irradiance is reduced, emphasizing the need for regular cleaning to maintain efficiency.
| Irradiance (W/m²) | Short-Circuit Current (A) | Open-Circuit Voltage (V) | Maximum Power (W) |
|---|---|---|---|
| 400 | 3.28 | 30.1 | 85 |
| 600 | 4.92 | 30.3 | 128 |
| 800 | 6.56 | 30.5 | 172 |
| 1000 | 8.21 | 30.7 | 215 |
Ambient temperature plays a crucial role in the operational efficiency of solar panels. We evaluated temperatures of -10°C, 0°C, 25°C, and 50°C, with fixed irradiance at 1000 W/m², wind speed at 3 m/s, and transmittance at 0.45. The simulations reveal that temperature has a pronounced effect on ( U_{oc} ), which decreases as temperature rises, while ( I_{sc} ) experiences a slight increase. This inverse relationship is attributed to the semiconductor properties of solar panels; higher temperatures reduce the bandgap energy, increasing minority carrier concentrations and thus slightly boosting current, but also raising recombination losses that lower voltage. The net effect is a reduction in ( P_{\text{max}} ) with increasing temperature, as shown in Table 2. For instance, at -10°C, ( P_{\text{max}} ) is approximately 240 W, but it drops to 180 W at 50°C. This highlights the thermal management challenges in hot climates, where solar panels may require cooling mechanisms to sustain performance.
| Ambient Temperature (°C) | Short-Circuit Current (A) | Open-Circuit Voltage (V) | Maximum Power (W) |
|---|---|---|---|
| -10 | 8.05 | 33.5 | 240 |
| 0 | 8.10 | 32.2 | 225 |
| 25 | 8.21 | 30.7 | 215 |
| 50 | 8.32 | 29.0 | 180 |
Wind speed influences solar panel temperature through convective cooling. We tested wind speeds of 1 m/s, 3 m/s, 5 m/s, and 8 m/s, with irradiance at 1000 W/m², ambient temperature at 25°C, and transmittance at 0.45. The results indicate that wind speed has a minimal impact on ( I_{sc} ) but significantly affects ( U_{oc} ), which increases with higher wind speeds due to enhanced heat dissipation. This cooling effect reduces the solar panel temperature, as described by the empirical models, leading to improved voltage and power output. Table 3 demonstrates that ( P_{\text{max}} ) rises from 191 W at 1 m/s to 208 W at 8 m/s. This underscores the benefit of natural ventilation in desert installations, where high winds can partially counteract the negative effects of high irradiance and dust accumulation on solar panels.
| Wind Speed (m/s) | Short-Circuit Current (A) | Open-Circuit Voltage (V) | Maximum Power (W) |
|---|---|---|---|
| 1 | 8.20 | 29.8 | 191 |
| 3 | 8.21 | 30.7 | 215 |
| 5 | 8.21 | 31.2 | 224 |
| 8 | 8.22 | 31.8 | 240 |
Dust deposition on solar panels reduces glass transmittance, directly diminishing the effective irradiance. We simulated transmittance values of 0.45, 0.65, 0.85, and 1.0 (clean panels), with irradiance at 1000 W/m², ambient temperature at 25°C, and wind speed at 3 m/s. As transmittance decreases, ( U_{oc} ) and ( P_{\text{max}} ) decline, while ( I_{sc} ) remains relatively stable. This is because dust blocks sunlight, reducing the photon flux and thus the photogenerated current, but the primary impact is on voltage due to the lower energy input. Table 4 shows that ( P_{\text{max}} ) drops from 240 W for clean solar panels to 182 W at a transmittance of 0.45, highlighting the critical need for maintenance in dusty environments. Additionally, dust can cause localized heating and potential hot spots, further degrading solar panel longevity and efficiency.
| Transmittance | Short-Circuit Current (A) | Open-Circuit Voltage (V) | Maximum Power (W) |
|---|---|---|---|
| 0.45 | 8.21 | 29.5 | 182 |
| 0.65 | 8.21 | 30.2 | 205 |
| 0.85 | 8.21 | 30.9 | 228 |
| 1.00 | 8.21 | 31.5 | 250 |
To further quantify the combined effects, we derived sensitivity coefficients for each factor. The change in maximum power (( \Delta P_{\text{max}} )) can be approximated as:
$$\Delta P_{\text{max}} = \alpha_G \Delta G + \alpha_T \Delta T + \alpha_V \Delta V + \alpha_\beta \Delta \beta$$
where ( \alpha_G ), ( \alpha_T ), ( \alpha_V ), and ( \alpha_\beta ) are sensitivity coefficients derived from simulation data. For instance, ( \alpha_G \approx 0.2 \, \text{W per W/m²} ), indicating a strong positive correlation with irradiance, while ( \alpha_T \approx -1.5 \, \text{W per °C} ), reflecting the negative impact of temperature. Wind speed and transmittance have positive coefficients of approximately ( \alpha_V \approx 5 \, \text{W per m/s} ) and ( \alpha_\beta \approx 150 \, \text{W per unit transmittance} ), respectively. These coefficients aid in designing adaptive control systems for solar panels in variable environments.
In conclusion, our numerical analysis demonstrates that solar panel output is highly sensitive to environmental factors. Irradiance predominantly governs short-circuit current and power output, while temperature inversely affects open-circuit voltage. Wind speed provides beneficial cooling, enhancing voltage and power, and dust deposition significantly reduces performance by lowering effective irradiance. These insights are vital for optimizing solar panel installations in desert regions, where factors like dust and high temperatures are prevalent. Future work could integrate real-time monitoring and machine learning to dynamically adjust operations, ensuring maximum efficiency and longevity of solar panels. Overall, this study underscores the importance of holistic environmental considerations in the design and maintenance of photovoltaic systems.