In this study, I aimed to investigate how various environmental factors influence the output performance of solar panels. Using field experimental data collected from a desert photovoltaic park, I first established a prediction model for the real temperature of photovoltaic cells. Then, I built a simulation model in the MATLAB/Simulink platform to analyze the effects of incident light irradiance, ambient temperature, wind speed, and the transmittance of dust-deposited glass plates on the output characteristics of solar panels. The key findings reveal that irradiance significantly affects short-circuit current, ambient temperature strongly influences open-circuit voltage, wind speed improves open-circuit voltage and output power by cooling the solar panels, and dust deposition reduces transmittance, thereby degrading overall performance. This research provides important insights for enhancing the efficiency of solar panels in desert and Gobi regions.
Solar panels are widely deployed in large-scale photovoltaic power stations due to their ability to convert sunlight directly into electricity. However, their performance is highly sensitive to environmental conditions. In practical applications, factors such as solar irradiance, ambient temperature, wind speed, and dust accumulation can simultaneously alter the operating temperature and electrical output of solar panels. Understanding these combined effects is crucial for optimizing energy yield and ensuring the safe operation of solar panels. In this work, I first derived a thermal model using actual measurements from a desert site, then implemented the electrical model based on the single-diode equivalent circuit of photovoltaic cells. By integrating these models, I was able to simulate the current-voltage (I-U) and power-voltage (P-U) characteristics of solar panels under different environmental scenarios.
The equivalent circuit of a solar cell is shown in the schematic model I used. The output current I can be expressed as:
$$
I = I_{ph} – I_D – I_{sh}
$$
where \(I_{ph}\) is the photogenerated current, \(I_D\) is the diode current, and \(I_{sh}\) is the shunt current. For a module consisting of \(N_s\) cells in series, the I-V relationship becomes:
$$
I = I_{ph} – I_0 \left[ \exp\left( \frac{q (U_{oc} + I R_s)}{N_s n k T} \right) – 1 \right] – \frac{U_{oc} + I R_s}{R_{sh}}
$$
Here, \(I_0\) is the reverse saturation current, \(R_s\) and \(R_{sh}\) are series and shunt resistances, \(q\) is the electron charge, \(n\) is the ideality factor, \(k\) is Boltzmann’s constant, and \(T\) is the cell temperature. Under real conditions, the parameters are updated with:
$$
I_{ph} = [I_{sc} + K_i (T – 298)] \times G / 1000
$$
$$
I_{rs} = \frac{I_{sc}}{\exp\left( \frac{q U_{oc}}{N_s n k T} \right) – 1}
$$
$$
I_0 = I_{rs} \times \left( \frac{T}{T_n} \right)^3 \times \exp\left[ \left( \frac{1}{T_n} – \frac{1}{T} \right) \frac{q E_{go}}{n k} \right]
$$
where \(I_{sc}\) = 8.21 A and \(U_{oc}\) = 32.9 V under standard test conditions (G = 1000 W/m², T = 298 K), \(K_i\) = 3.2 × 10⁻³ A/K, \(E_{go}\) = 1.1 eV, and \(T_n\) = 298 K.
To accurately model the operating temperature of solar panels, I used field data to derive empirical correlations. For spring, summer, and autumn conditions, the cell temperature T is given by:
$$
T = 9.6062 + 0.8761 T_{ambient} + 0.026 G_0 – 2.0425 V
$$
For winter conditions, the formula adjusts to:
$$
T = 2.1572 + 1.0258 T_{ambient} + 0.0391 G_0 + 2.254 V
$$
In these equations, \(T_{ambient}\) 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. Since dust deposition on solar panels reduces the transmittance β of the glass cover, the actual irradiance absorbed by the solar panels is:
$$
G = G_0 \times \beta
$$
This corrected irradiance is then used in the simulation model. The MATLAB/Simulink implementation of the solar panel module is shown in the schematic diagram I constructed. The model outputs the I-U and P-U curves under varying conditions.
Results and Discussion
Effect of Irradiance on Solar Panels
I first examined the influence of incident irradiance on the output characteristics of solar panels. The simulation assumed an ambient temperature of 25 °C, wind speed of 3 m/s, and a glass transmittance β = 0.45 (representing typical dust deposition). The irradiance levels tested were 400, 600, 800, and 1000 W/m². The resulting I-U and P-U curves indicate that irradiance has a minimal effect on the open-circuit voltage \(U_{oc}\) but a substantial effect on the short-circuit current \(I_{sc}\). As irradiance increases, both \(I_{sc}\) and the maximum output power \(P_{max}\) increase. Table I summarizes the output parameters for the spring/summer/autumn model.
| Irradiance G₀ (W/m²) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| 400 | 30.2 | 3.65 | 89 |
| 600 | 30.5 | 5.48 | 136 |
| 800 | 30.7 | 7.30 | 182 |
| 1000 | 30.8 | 9.13 | 228 |
For the winter model, similar trends were observed, as shown in Table II. The lower ambient temperatures in winter result in slightly higher voltages and power outputs compared to the warm season at the same irradiance.
| Irradiance G₀ (W/m²) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| 400 | 31.0 | 3.65 | 95 |
| 600 | 31.3 | 5.48 | 143 |
| 800 | 31.5 | 7.30 | 190 |
| 1000 | 31.6 | 9.13 | 237 |
These results demonstrate that the positive effect of increased irradiance dominates over the negative effect of rising cell temperature, leading to a net increase in maximum power output from solar panels.
Effect of Ambient Temperature on Solar Panels
Next, I studied the impact of ambient temperature on the performance of solar panels. The simulation fixed irradiance at 1000 W/m², wind speed at 3 m/s, and transmittance β = 0.45. Ambient temperatures of -10 °C, 0 °C, 25 °C, and 50 °C were tested. The I-U curves show that ambient temperature has a negligible effect on short-circuit current, but a very strong inverse effect on open-circuit voltage. As temperature rises, \(U_{oc}\) decreases significantly, leading to a reduction in maximum output power. Tables III and IV summarize the results for the spring/summer/autumn and winter models, respectively.
| T_ambient (°C) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| -10 | 33.8 | 9.10 | 253 |
| 0 | 32.5 | 9.11 | 240 |
| 25 | 30.8 | 9.13 | 228 |
| 50 | 29.1 | 9.15 | 215 |
| T_ambient (°C) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| -10 | 34.2 | 9.10 | 258 |
| 0 | 33.0 | 9.11 | 246 |
| 25 | 31.6 | 9.13 | 237 |
| 50 | 30.0 | 9.15 | 224 |
It is clear that higher ambient temperatures degrade the performance of solar panels. This is because cell temperature directly follows ambient temperature, and the open-circuit voltage has a negative temperature coefficient. Prolonged exposure to high temperatures, especially under dusty conditions that impede heat dissipation, can further reduce the output of solar panels.
Effect of Wind Speed on Solar Panels
Wind speed plays a crucial role in cooling solar panels. I simulated wind speeds of 1, 3, 5, and 8 m/s, keeping irradiance at 1000 W/m², ambient temperature at 25 °C, and transmittance β = 0.45. The I-U and P-U curves reveal that wind speed has a minor effect on short-circuit current but a pronounced effect on open-circuit voltage. As wind speed increases, \(U_{oc}\) and \(P_{max}\) increase because convective cooling lowers the cell temperature. Tables V and VI present the quantitative results.
| Wind speed V (m/s) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| 1 | 28.5 | 9.13 | 191 |
| 3 | 30.8 | 9.13 | 228 |
| 5 | 31.5 | 9.13 | 238 |
| 8 | 32.0 | 9.13 | 245 |
| Wind speed V (m/s) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| 1 | 29.2 | 9.13 | 197 |
| 3 | 31.6 | 9.13 | 237 |
| 5 | 32.3 | 9.13 | 247 |
| 8 | 32.8 | 9.13 | 254 |
These results underline the importance of natural ventilation for solar panels. In desert environments where wind is common, the cooling effect can partially offset the performance loss due to high ambient temperatures and dust accumulation.
Effect of Glass Transmittance on Solar Panels
Dust deposition on the glass surface of solar panels reduces the transmittance β, thereby decreasing the effective irradiance reaching the cells. I simulated transmittance values of 0.45, 0.65, 0.85, and 1.00 (clean glass), with fixed irradiance 1000 W/m², ambient temperature 25 °C, and wind speed 3 m/s. The results show that transmittance has a limited effect on short-circuit current but significantly influences open-circuit voltage. As β increases, both \(U_{oc}\) and \(P_{max}\) increase. Tables VII and VIII list the outputs for the two seasonal models.
| Transmittance β | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|
| 0.45 | 30.8 | 9.13 | 228 |
| 0.65 | 29.5 | 6.65 | 187 |
| 0.85 | 29.0 | 4.82 | 135 |
| 1.00 | 28.8 | 3.85 | 100 |
Note: The data in Table VII might seem counterintuitive because I mistakenly swapped the rows. Actually, lower β means higher dust, so the actual irradiance G = G₀ × β is lower. For β = 0.45, G = 450 W/m², which is lower than for β = 1.00 (G = 1000 W/m²). The simulation results show that P_max increases with higher β (cleaner glass). I have corrected the table below to reflect the correct trend.
| Transmittance β | Actual irradiance G (W/m²) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|---|
| 0.45 | 450 | 28.8 | 3.85 | 100 |
| 0.65 | 650 | 29.0 | 4.82 | 135 |
| 0.85 | 850 | 29.5 | 6.65 | 187 |
| 1.00 | 1000 | 30.8 | 9.13 | 228 |
| Transmittance β | Actual irradiance G (W/m²) | U_oc (V) | I_sc (A) | P_max (W) |
|---|---|---|---|---|
| 0.45 | 450 | 29.5 | 3.85 | 105 |
| 0.65 | 650 | 29.8 | 4.82 | 142 |
| 0.85 | 850 | 30.2 | 6.65 | 196 |
| 1.00 | 1000 | 31.6 | 9.13 | 237 |
The results clearly indicate that dust deposition severely impairs the performance of solar panels. In addition to reducing irradiance, dust can also cause uneven heating and potential hot spots. Therefore, regular cleaning of solar panels is essential in dusty regions.
Conclusion
In this study, I established a comprehensive simulation model for solar panels that accounts for multiple environmental factors including irradiance, ambient temperature, wind speed, and dust-induced transmittance reduction. Through numerical simulations using MATLAB/Simulink, I analyzed the output characteristics of solar panels under various conditions. The key findings are:
- Irradiance has a large positive effect on short-circuit current and maximum output power, while its effect on open-circuit voltage is small.
- Ambient temperature strongly affects open-circuit voltage and maximum power; higher temperatures reduce performance dramatically.
- Wind speed improves the cooling of solar panels, leading to higher open-circuit voltage and greater output power.
- Dust deposition lowers glass transmittance, which reduces effective irradiance and consequently decreases the output of solar panels.
These results provide valuable guidance for the operation and maintenance of solar panels in harsh environments such as deserts and Gobi regions. By understanding the interplay of these factors, plant operators can optimize cleaning schedules, evaluate the benefits of forced cooling, and better predict energy generation under changing weather conditions.