Created by E.Ö., SUPSI, on 13.11.2024
When designing Alpine PV modules, it is essential to consider the specific environmental challenges posed by the alpine environment. This includes cold temperatures, heavy snow loads, high wind speeds, large temperature variations, UV exposure, and potential mechanical stresses. Below are key considerations for the design of Alpine PV modules, which are also summarized in Figure 1:
Figure 1: Alpine PV module design. (source: SUPSI)
1. Frame
- Reinforced Frames with High Bending Resistance: Use frames specifically designed to resist higher snow loads and wind stresses, with a focus on increased mechanical stability. Frames should withstand high loads without deforming.
- Larger Contact Surface to the Glass: Ensure the frame has a larger contact area with the glass to distribute loads more evenly, minimizing the risk of cracks or mechanical failure under high loads.
- Special Geometries for Snow Shedding: Incorporate designs that avoid snow accumulation and promote the drainage of melting water. Snow-shedding geometries can reduce the weight burden on the module.
- Glued Frames: The use of glued frames provides additional structural integrity and helps prevent snow and wind-driven moisture from entering module edges.
2. Front Layer
- Tempered and Thick Glass: Thick and tempered glass offers superior mechanical strength against snow, ice, and hail impact, crucial for high-load environments.
- Special Coatings: Coatings designed to shed snow and ice more efficiently, reducing accumulation and enhancing energy yield during winter months.
3. Encapsulants (Front and Back)
- Reduced Stiffness at Low Temperatures: Choose encapsulant materials that retain flexibility at low temperatures to reduce the risk of cracking.
- High UV Resistance: Both front and back encapsulants must offer high UV resistance to avoid degradation, especially in areas with high UV exposure.
- Increased Layer Thickness: Use thicker encapsulants to better protect cells and interconnects from mechanical stresses, particularly important for Alpine modules subjected to high loads.
- UV-cut Encapsulants: Encapsulants with UV-blocking properties to protect UV-sensitive solar cells (i.e. PERC, HJT and TOPCon).
4. Solar Cells
- Bifacial Cells: These enhance energy yield in alpine regions due to reflective surfaces like snow, which increases irradiance on the rear side of the module.
- Multi-busbar/Wire Contacts: These improve resilience to micro-cracks and enhance current flow, making the module more durable under mechanical stresses like snow loads.
- High UV Stability: Cells must maintain their efficiency under high UV conditions.
- Low-temperature and High Irradiance Performance: Select cells that perform well under low-temperature and high irradiance conditions, characteristic of alpine environments.
5. Rear Layer (Backsheet or Glass)
- Tempered and Thick Rear Glass (for Glass/Glass Modules): This offers added durability and mechanical strength, which is critical in Alpine environments with heavy snow loads.
- UV-resistant Backsheet (for Glass/Backsheet Modules): In Glass/Backsheet configurations, a UV-resistant backsheet is essential to protect against long-term exposure to UV radiation, moisture, and temperature fluctuations.
6. Junction Box and Cables
- High UV Resistance: Ensure that the junction box and cables are UV-resistant to withstand prolonged sun exposure.
- Sealing and Adhesives Resistant to Low Temperatures: Use materials for sealing and bonding that retain flexibility and integrity at low temperatures, preventing cracks or failure due to thermal expansion.
- Bypass Diodes for High Currents: Install bypass diodes capable of handling high currents, especially in bifacial modules exposed to high irradiance conditions.
7. Clamps and Mounting Structure
- Reinforced Clamps: Use reinforced clamp materials capable of withstanding heavy snow and wind loads.
- Optimized Number and Positioning: Place the clamps at optimal points along the module’s edges (preferably along the long edges) to distribute mechanical loads evenly.
- Rubber Inserts: Use rubber inserts in the clamps to reduce the mechanical stress on the module, especially in high-vibration or thermal expansion scenarios.
- Robust Back Rails and Four-sided Clamping: For high-load environments, ensure the module is supported by robust back rails (for monofacial modules) and four-sided clamping, providing even weight distribution and minimizing module deflection.
- Reinforced Mounting Structure: Ensure the supporting structures can withstand high wind speeds and snow loads typical in alpine environments.
