By taking reference on the windspeed table below, we can understand pascals pressure on the solar structure and modules.
| Metres/Second m/s | Kilometres/Hour km/h | Miles/Hour mph | Pascals Pa | ||
| 6.38 | 22.97 | 14.28 | 25 | ||
| 9.03 | 32.50 | 20.19 | 50 | ||
| 11.06 | 39.80 | 24.73 | 75 | ||
| 12.77 | 45.96 | 28.56 | 100 | ||
| 15.63 | 56.27 | 34.97 | 150 | ||
| 18.06 | 65.00 | 40.39 | 200 | ||
| 20.18 | 72.66 | 45.16 | 250 | ||
| 22.11 | 79.60 | 49.46 | 300 | ||
| 23.88 | 85.97 | 53.43 | 350 | ||
| 25.53 | 91.91 | 57.11 | 400 | ||
| 27.08 | 97.47 | 60.58 | 450 | ||
| 28.54 | 102.76 | 63.85 | 500 | ||
| 31.27 | 112.56 | 69.94 | 600 | ||
| 33.77 | 121.57 | 75.54 | 700 | ||
| 36.11 | 130.00 | 80.78 | 800 | ||
| 38.30 | 137.88 | 85.67 | 900 | ||
| 40.31 | 145.13 | 90.18 | 1000 | ||
| 42.34 | 152.42 | 94.71 | 1100 | ||
| 44.22 | 159.19 | 98.92 | 1200 | ||
| 46.03 | 165.72 | 102.97 | 1300 | ||
| 47.77 | 171.96 | 106.85 | 1400 | ||
| 49.44 | 178.00 | 110.60 | 1500 | ||
| 51.06 | 183.83 | 114.23 | 1600 | ||
| 54.16 | 194.97 | 121.15 | 1800 | ||
| 57.09 | 205.53 | 127.71 | 2000 | ||
| 59.87 | 215.60 | 133.94 | 2200 | ||
| 62.54 | 225.10 | 139.90 | 2400 | ||
| 65.09 | 234.30 | 145.61 | 2600 | ||
| 67.54 | 243.20 | 151.10 | 2800 | ||
| 69.92 | 251.70 | 156.41 | 3000 | ||
| 72.21 | 260.00 | 161.53 | 3200 | ||
| 74.44 | 268.00 | 166.52 | 3400 | ||
| 76.54 | 275.70 | 171.33 | 3600 | ||
| 78.69 | 283.30 | 176.03 | 3800 | ||
| 80.74 | 290.70 | 180.61 | 4000 | ||
| 82.73 | 297.80 | 185.06 | 4200 | ||
| 84.68 | 304.80 | 189.42 | 4400 | ||
| 86.58 | 311.70 | 193.68 | 4600 | ||
| 88.45 | 318.40 | 197.86 | 4800 | ||
| 90.27 | 325.00 | 201.92 | 5000 | ||
| 92.05 | 331.40 | 205.91 | 5200 | ||
| 93.79 | 337.60 | 209.80 | 5400 | ||
| 95.54 | 344.00 | 213.72 | 5600 | ||
| 97.22 | 350.00 | 217.48 | 5800 | ||
| 98.87 | 356.00 | 221.18 | 6000 | ||
| 1000 pascals + 1 kPa | 20.89 lbs ft | ² = 1 kPa | |||
Modules level- wind load
Referring to the data sheets of most solar modules, it’s evident that they typically withstand up to 2400pa, equivalent to approximately 62.52m/s wind uplift force. Therefore, when customers or government guidelines mandate designing a solar structure to endure higher winds, like 72m/s, equating to about 3200pa, the warranty coverage from the solar modules has already peaked. Consequently, in cases of high wind loads, the module supplier wouldn’t be held liable.
Solar structure – wind load
Many solar structure suppliers often claim that their systems can withstand high winds up to 85 m/s. However, this is frequently not true. Different solar clamps, roof profiles, materials, or thicknesses can yield varying results in the ultimate load profile. To justify such statements, manufacturers should provide test reports. Widely recognize test reports in the solar industry include UL2703, UL1703, and IEC61730.
Building structure – Wind Load
Wind building codes vary significantly across different countries, taking into account local climate conditions, building practices, and engineering standards. Here are some notable wind building codes from various countries:
United States
- ASCE 7 (American Society of Civil Engineers): This standard, specifically ASCE 7-16, provides the minimum design loads for buildings and other structures, including wind load provisions. It is widely used in building codes across the United States.
Europe
- Eurocode 1 (EN 1991-1-4): This is part of the Eurocodes suite of standards, specifically addressing wind actions on structures. It provides detailed methods for calculating wind loads based on factors like location, terrain, and building height.
Australia and New Zealand
- AS/NZS 1170.2: This standard specifies structural design actions, including wind actions. It takes into account regional wind speeds, terrain categories, and building shapes.
Canada
- NBCC (National Building Code of Canada): The NBCC includes provisions for determining wind loads on buildings and structures, based on geographical location, building height, and exposure conditions.
Japan
- AIJ Recommendations for Loads on Buildings: These guidelines by the Architectural Institute of Japan provide detailed methods for calculating wind loads, considering factors like typhoons, which are common in the region.
China
- GB 50009-2012: This is the national standard for the load code of building structures in China, including wind load calculations based on various geographic and topographic conditions.
India
- IS 875 (Part 3): This Indian Standard provides guidelines for calculating wind loads on buildings and structures. It considers factors like wind speed, terrain, and building height.
United Kingdom
- BS EN 1991-1-4 (Eurocode 1): The UK uses the Eurocode standards, with specific national annexes that adapt the general Eurocode provisions to local conditions.
Brazil
- NBR 6123: This Brazilian standard specifies the criteria for determining wind actions on buildings, considering regional wind speeds and building characteristics.
South Africa
- SANS 10160-3: This South African National Standard provides guidelines for the design of structures subjected to wind loads, accounting for local wind conditions.
Russia
- SP 20.13330.2016: This standard, part of the set of Russian building codes, includes provisions for calculating wind loads on structures.
Indonesia
- SNI 03-1727-2020 (Standar Nasional Indonesia): This standard provides guidelines for the calculation of wind loads on buildings and other structures. It considers factors such as wind speed, terrain, and building height.
Malaysia
- MS 1553:2002 (Code of Practice on Wind Loading for Building Structure): This Malaysian standard outlines the procedures for determining wind loads on structures. It takes into account local wind speeds, topography, and the geometry of buildings.
Philippines
- NSCP (National Structural Code of the Philippines): Specifically, the NSCP 2015 edition (Volume 1) includes detailed provisions for wind load calculations. The code considers typhoon-prone conditions, which are common in the Philippines, and includes detailed guidelines for designing structures to withstand high wind speeds.
Singapore
- CP 38:1999 (Code of Practice for Wind Loads): This code provides guidelines for calculating wind loads on buildings and structures in Singapore. It includes considerations for wind speed, building height, and exposure category.
Thailand
- DPT Standard (Department of Public Works and Town & Country Planning): Thailand uses guidelines based on both local standards and adaptations of international standards like ASCE 7 for determining wind loads on structures. The Thai code takes into account local wind speeds and building characteristics.
Vietnam
- TCVN 2737:1995 (Vietnamese Standard for Loads and Actions): This standard includes provisions for calculating wind loads on buildings. It considers regional wind speeds, terrain types, and the height and shape of structures.
Key Considerations in Wind Building Codes:
- Regional Wind Speeds: Different regions experience different maximum wind speeds, which significantly influence design requirements.
- Terrain Categories: The roughness of the terrain can impact wind speed and pressure on structures.
- Building Height and Shape: Taller buildings and more complex structures require more detailed wind load analysis.
- Exposure Conditions: Buildings in open areas are subjected to higher wind pressures compared to those in sheltered locations.
- Typhoon Prone Areas: Countries like the Philippines and Vietnam experience frequent typhoons, requiring more stringent wind load provisions.
- Local Wind Patterns: Each country’s wind building codes take into account their unique wind patterns
Compliance with these codes ensures that buildings and structures can withstand local wind conditions, thereby enhancing their safety and durability. However, in developing countries, budget constraints often lead to non-compliance with local codes. Consequently, solar installers may fail to realize that if the architecture does not comply with local wind codes, even designing the solar system to withstand high winds will not suffice.
To conclude, the structural integrity of solar installations is crucial but often overlooked as the weakest link when project managers aim to reduce material costs. It’s essential to consider the overall picture to ensure that the building structure can withstand high winds. Currently, there are no codes and standards mandating pullout tests on actual roofs to confirm wind uplift resistance. Therefore, we recommend the following:
- Solar Structure Testing: Conduct tests in an ISO 17025 certified lab.
- Pullout Anchorage Test: Test in at least two load directions—negative normal and parallel to the roof.
- Actual Application Test: Perform tests on the actual roof material (substrate) used in the project to ensure accurate results.
- Solar Clamps Production: Ensure solar clamps are produced in a certified ISO 9001:2015 factory to guarantee uniformity and safety for deployment.