Factors Affecting Photovoltaic Power Plant Output in Winter and Mitigation Measures
1. Low-Temperature Characteristics of PV Modules
In low-temperature environments, the open-circuit voltage (Voc) of PV modules increases, and the short-circuit current (Isc) slightly rises. However, since module power output is negatively correlated with temperature, colder conditions generally reduce module efficiency. Most PV modules have a maximum power temperature coefficient of approximately -0.35%/°C. For example, when temperatures drop from 25°C to -10°C, the efficiency of conventional crystalline silicon modules may decrease by 5–10%. Additionally, lower temperatures can elevate the output voltage of PV arrays, potentially exceeding the inverter’s maximum input voltage and disrupting normal operation.
Mitigation Measures:
During design and installation, account for the low-temperature behavior of PV modules. For instance, if a module’s Voc under standard test conditions (STC) is 50V with a temperature coefficient of -0.3%/°C, its actual Voc at -10°C would be:
V = 50 × [1 + (-10 – 25) × (-0.3%)] = 55.25V.Ensure string designs account for local minimum temperatures to prevent exceeding inverter voltage limits, which could trigger protective shutdowns or reduce output.
2. Cable and Connector Issues
Winter temperatures can make cable insulation brittle, leading to cracks or damage. Connectors may loosen due to thermal expansion and contraction, causing poor contact or disconnection. Minor issues may prevent inverters from feeding power to the grid, while severe cases pose safety risks.
Mitigation Measures:
Implement a winter maintenance plan to regularly inspect module surfaces, cables, connectors, and inverter operation.
Promptly address loose connections, damaged insulation, or other anomalies to ensure stable and safe system performance.
3. Haze, Dust, and Pollution
Dry winter air increases airborne dust, while frequent haze reduces solar radiation penetration. Dust accumulation on module surfaces lowers light transmittance and efficiency. Prolonged shading from debris (e.g., bird droppings, leaves) can also induce hot spot effects, damaging modules and creating safety hazards.
Mitigation Measures:
Clean modules regularly, increasing frequency during winter. Prioritize removing localized debris (e.g., bird droppings) to minimize shading losses.
4. Snow Accumulation
Snow covering modules blocks sunlight, causing a sharp decline or complete loss of power output. Heavy snow buildup may also risk structural collapse.
Mitigation Measures:
Remove snow promptly using soft tools (e.g., foam brushes) to avoid scratching modules. Do not step on modules during cleaning, as this may cause micro-cracks.
Avoid waiting for thick snow accumulation, as ice formation complicates removal. Never pour hot water on icy modules.
Clear partial or patchy snow, as even localized coverage can reduce the output of entire strings.
For snow-prone regions, consider increasing the installation tilt angle during design to minimize snow retention.
Summarize
By addressing these factors through proactive design, installation adjustments, and seasonal maintenance, PV plant operators can mitigate winter-related losses and optimize annual energy yields.