Created by E.Ö., SUPSI, on 19.08.2024
It is crucial to subject photovoltaic (PV) modules designed for use in Alpine environments to stringent testing to guarantee their ability to endure harsh environmental factors, including extreme temperatures, strong winds, heavy snowfall, and high levels of UV radiation. The potential alpine stressors are detailed in Alpine PV Stressors. The International Electrotechnical Commission (IEC) has established several standards that are particularly relevant for such conditions. Here are the critical standard PV module tests for Alpine PV modules:
- Static Mechanical Load Test (IEC 61215-2:2021, MQT 16)
Description: This test evaluates the module’s structural integrity under homogenous static mechanical stress, simulating snow loads and wind pressures.
Relevance: Alpine regions often have heavy snowfalls and strong winds, making it essential for modules to withstand such mechanical stress without damage. To address these demanding conditions, some manufacturers produce specialized alpine modules designed to withstand static mechanical loads that exceed standard IEC requirements, such as up to +8000 Pa.
- Non-uniform Snow Load Test (IEC 62938:2020)
Description: This test outlines how to simulate and evaluate the impact of unevenly distributed snow loads on PV modules. It involves applying a non-uniform load to the module and monitoring its structural integrity under this condition.
Relevance: In Alpine regions, PV modules often face substantial, uneven snow loads due to the rugged terrain and severe winter conditions. The uneven snow distribution can cause significant strain, potentially leading to mechanical failure. This test ensures that modules and their mounting systems can withstand non-uniform loads safely, reducing the risk of accidents.
- Cyclic (dynamic) Mechanical Load Test (IEC 61215-2:2021, MQT 16) and PV Modules – Cyclic (dynamic) Mechanical Load Test (IEC TS 62782:2016)
Description: This test evaluates the module’s structural integrity under homogenous cyclic (dynamic) mechanical stress, simulating cyclic mechanical loads due to wind.
Relevance: Alpine regions often have strong wind gusts, making it essential for modules and their mounting systems to withstand possible cyclic mechanical loads without damage.
- Hail Impact Test (IEC 61215-2:2021, MQT 17), PV Modules – Qualifying guidelines for increased hail resistance (IEC TS 63397:2022) and VKF Prüfbestimmungen (ACFI Test Specifications)
Description: This test simulates the impact of hailstones on PV modules to assess their resistance to physical damage. According to the IEC 61215 standard, a PV module must withstand the impact of a 25 mm hailstone launched at 80 km/h. In comparison, the Swiss VKF standard requires a minimum hailstone size of 30 mm (HW 3, hail resistance class 3), with discussions currently underway to increase this minimum to 40 mm (HW 4, hail resistance class 4) for hail-prone zones.
Relevance: Hailstorms can be frequent in mountainous areas, and this test ensures the modules can withstand such impacts.
- Ultraviolet (UV) Test (IEC 61215-2:2021, MQT 10)
Description: This test checks the module’s ability to endure long-term exposure to UV radiation.
Relevance: High altitudes have increased UV radiation, necessitating robust resistance to UV degradation. Extended UV exposure tests (beyond the standard) may be necessary to conduct to assess the long-term effects of high-altitude UV radiation on PV modules.
- Bypass Diode Thermal Test (IEC 61215-2:2021, MQT 18.1)
Description: This test checks the functionality of bypass diodes under thermal stress.
Relevance: Ensures that bypass diodes, which protect against partial shading and hot spots, function correctly under higher irradiances and varying thermal conditions typical in Alpine climates.
- Thermal Cycling Test (IEC 61215:2021, MQT 11)
Description: This test evaluates the module’s ability to withstand the stresses caused by thermal expansion and contraction due to temperature fluctuations.
Relevance: Alpine regions experience significant temperature variations between day and night, making this test crucial.
- Humidity-Freeze Test (IEC 61215-2:2021, MQT 12)
Description: This test assesses the module’s resistance to moisture and freezing conditions by subjecting it to high humidity and freezing cycles.
Relevance: The combination of moisture and freezing temperatures is common in Alpine areas, which can affect module integrity and performance.
Ensuring PV modules pass these critical tests according to IEC standards increase confidence in their reliability, durability, and performance in the challenging conditions of Alpine regions. However, it is important to recognize that the stress levels encountered in Alpine conditions can exceed those covered by these standard tests. Therefore, it is crucial to apply these tests with caution, considering the specific working conditions and maximum stress levels typical of the Alpine environment.
Non-standard Testing
In addition to the standard tests outlined by the IEC for PV modules, non-standard tests may be necessary to ensure the safety, reliability and performance of PV modules in the harsh conditions typical of Alpine environments. These non-standard tests can be tailored to address the specific challenges posed by extreme weather. Here are some non-standard tests for PV modules in Alpine environments:
- Mechanical Load Test at Low Temperatures
Description: Mechanical load testing at low temperatures evaluates the module’s ability to withstand mechanical stresses such as snow loads, wind pressure, and potential impacts at low temperatures.
Relevance: By simulating mechanical load testing at low temperatures, manufacturers can ensure that their PV modules are robust enough to handle the challenging conditions in Alpine environments, thereby enhancing both performance and safety.
- Sequential Mechanical Load Test for Low Temperatures
Description: Sequential mechanical load test considering low temperatures involves subjecting PV modules to series of mechanical load test and low temperature exposure to mimic the stresses that modules experience over time in Alpine environment. This test may be preferable to the mechanical stress test at low temperatures, which may not be possible due to infrastructure capacity (i.e. performing mechanical load test at low temperatures).
Relevance: High mechanical loads, which can be caused by snow or wind in extremely cold Alpine regions, put additional stress on the modules. By creating sequence for mechanical stress and low temperature exposure, the test ensures that PV modules continue to perform safely and reliably, even under the harshest winter conditions typical of Alpine environments.
- Wind Tunnel Test
Description: Wind tunnel testing involves placing PV modules in a controlled environment where they are subjected to high-speed airflow to simulate the effects of wind. The primary objectives of wind tunnel testing are to determine aerodynamic forces, assess structural response and identify potential failure points.
Relevance: Alpine regions are known for their strong and turbulent winds, which can exert significant mechanical stress on PV modules and their mounting systems. Wind tunnel testing ensures that PV modules can withstand these forces without sustaining damage or becoming dislodged, which is critical for maintaining structural integrity, safety and preventing failures.
Sources:
IEC: Provides guidelines on testing the performance and reliability of PV modules under various environmental conditions.
Swiss VKF Standards: Set specific requirements for PV modules to withstand environmental stresses such as hail impact, which are relevant for ensuring module durability in Alpine regions.
