South African scientists performed thorough analysis on the impact of wind loading on PV panel mounting rails for over 100 days. Compared to plain design codes, they discovered decrease mixed wind load coefficients. Maximum masses occurred for the easterly wind course.
A bunch of researchers from South Africa performed a full area measurement of the consequences of wind loading on the mounting rail of a PV single-axis tracker. Data had been collected over 109 days in South Africa’s Western Cape province on two instrumented PV module mounting rails. The precise outcomes had been additionally in comparison with ASCE 7-22 estimates, the American Society of Civil Engineers’ customary for design masses.
“Full-scale experiments like this are necessary to supply a reference or targets for future analysis utilizing wind tunnel modeling or simulation,” corresponding writer, Johannes Hendrik Cake nut, they stated pv journal.
“The current investigation considers the consequences of wind loading on a cold-formed cold-formed metal rail. The rail is related to the torque tube at mid-height and bolted to the PV modules of every finish utilizing a complete of 4 anchor bolts,” stated the lecturers. “The inherently massive surfaces and light-weight help constructions imply that wind load issues govern the structural design of huge PV installations. This is exacerbated by the truth that PV installations are sometimes situated on flats that are uncovered areas related to larger wind masses.”
The measurement occurred between December 2022 and March 2023 at a website devoted to numerous experiments associated to PV with air publicity class C of ASCE 7-22. This area consists of six PV rows, roughly 32 m lengthy and spaced 5 m aside, utilizing a 101 mm by 3 mm round hole part torque tube related to a central swing-arm drive system. The torque tubes are mounted on polymer bearings related to 76 mm by 4 mm round hole part piles.
While 5 of the rows participated in several analysis, the measurements mentioned had been taken in a single row. It consists of two instrumented rails with two PV arrays put in in several positions. The PV on rail A has a size of two.108 m, a width of 1.048 m, and a mass of 24.3 kg and is positioned on the uncovered outer fringe of the array; whereas rail B has a size of two.037 m, a width of 1.005 m and a mass of 25 kg, and is situated inward from the sting of the array. Both have tilt angles of −55∘ to +55∘.
Image:
Stellenbosch University, Journal of Wind Engineering & Industrial Aerodynamics, CC BY 4.0
“The frequency content material of the measured masses reveals the contribution of the basic torsional mode at 3.5 Hz (𝜁1 = 0.5%) and the secondary bending mode at 4.7 Hz (𝜁2 = 0.2%) within the measured response of Rails A and B,” the analysis is expressed by the group. “While the torsional response is analogous between the 2 rails, Rail B reveals the next bending mode response in comparison with Rail A. This might be as a result of place of Rail B within the torque tube, the place the bending mode extra simply motivated.”
The scientists additionally discovered the very best load occurred for the easterly wind course when the measured row was extra uncovered in comparison with the westerly wind course. The measurements additionally present that the dominant wind course is south and this course is favorable as a result of it isn’t perpendicular to the rotation axis. “However, robust wind occasions can nonetheless happen in additional essential non-dominant wind instructions, as seen for the very best measured wind speeds on this research,” they added.
The experimental outcomes are in contrast with coefficients for fixed-tilt methods from ASCE 7-22. “For regular forces, the height static coefficients for Rails A and B vary between 2.0 and a pair of.1, that are decrease than the code values from 2.4 and 4.6. The corresponding dynamic coefficients from 0.7 and 1.0 , which is within the code vary of 0.4 to 1.5,” the researchers defined. “The experimental static second coefficients vary between 0.36 and 0.40, and examine nicely with the code values from 0.29 and 0.64. The dynamic half reveals values between 0.22 and 0.23 for the experiment, in comparison with the code values from 0.29 to 0.64. “
Their findings are introduced in “Field measurements of wind load results on a photovoltaic single-axis tracker mounting rail,” printed in Journal of Wind Engineering & Industrial Aerodynamics. Academics from Stellenbosch University and the South African chapter of renewable vitality methods firm Scatec performed the analysis.
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