DOI: 10.5281/zenodo.15133246
title: Non-Synoptic Wind Loads on Solar Panels

description: Dataset Description

The research focuses on non-synoptic (tornado, downburst, bora) wind loads acting on an array of solar panels. The non-synoptic wind is simulated inside the Wind Engineering, Energy, and Environment (WindEEE), and the flow characteristics are measured using a mini-drone with a 2D sonic anemometer. The non-synoptic wind is then simulated over a 25 scale pressure model of the array of solar panels, allowing for the measurement of the aerodynamic forces and moments acting on the solar panels situated in the array. This research also aims to provide the necessary knowledge to suggest guidelines for improved resilience of solar panels exposed to non-synoptic winds.

S0. Documentation

This folder contains important documents that pertain to the project. 

S1. Wind Profile Measurement Rack 1

Atmospheric boundary layer (ABL) and downburst wind simulations without a model were tested at the WindEEE Dome testing facility. Velocity measurement devices were used to characterize the wind profile and were mounted onto a vertical rack at heights of 5, 7.5, 10.0, 15.0, 20, 30.0, and 40.0 cm above the ground surface. The location of the vertical profile varied between the experiments outlined below.

E1. Straight Smooth Flow Profiling

The 60-fan wall located on one side of the hexagonal-shaped WindEEE test chamber was used to generate the various ABL flows for this experiment. During the experiment, 3-D point measurements were taken to characterize the velocity profiles for four uniform smooth flows of various wind speeds.

The vertical rack (where the measurements of the profile are taken) was positioned at radial distance (R) of 0 cm and at an azimuth angle (φ) of 0 degrees. An additional measurement, at a height of 120 cm, was used to take a reference measurement. These measurements aim to provide detailed characteristics of the wind profile. 

E2. BORA Wind Profiling

During this experiment, the 60-fan wall was used to generate BORA (gusting) wind by varying the speed of the fans with time. BORA winds with gust speed ratios of 2:1, 3:1, 4:1, 7:2, and 9:2, and gust duration ratios of 1:1, 2:1, and 3:1 were profiled using the 3-D point measurements on the vertical rack. Additionally, field measurement simulations were also tested using time-varying fan speeds that were at no specific ratio for speed or duration. These tests were conducted with or without roughness elements.

The vertical rack (where the measurements of the profile are taken) was positioned R=0 cm and φ=0 degrees. An additional position on the vertical rack (height of 120 cm) was used to take a reference measurement. These measurements aim to provide detailed characteristics of the wind profile. 

E3. Downburst Wind Profiling

An impinging-jet style downburst is generated at the WindEEE dome through the release of pressure from a plenum above the testing chamber. These impinging jets can be combined with the 60-fan wall to achieve an ABL and downburst-like flow configurations. During this experiment, 3-D point measurements were taken to characterize the velocity profiles for downbursts with or without ABL wind. For the downburst simulations, three parameters were varied: the strength of the impinging jet flow, the strength of the ABL wind flow, and the position of the bell mouth (L) within the WindEEE dome.

The vertical rack was positioned at radial distances from the center of the turntable (rm) at 75, 135, and 225 cm and with φ=180 degrees. Two additional locations for the vertical rack were at rm = 135cm with φ being 205 and 235 degrees.  An additional vertical rack was positioned on the opposite side of the bell mouth as the profiling rack to take a reference measurement at a height of 7.5 cm. These measurements aim to provide detailed characteristics of the wind profile. 

S2. Wind Profile Measurement Rack 2 (Tornado)

Translating tornado simulations without a model was tested at the WindEEE Dome testing facility. Four velocity measurement devices were used to characterize the wind profile. They were mounted onto a ground surface panel, with the devices aligned linearly perpendicular to the translating tornado’s path and spaced 10 cm apart.

E1. Tornado Wind Profiling

During this test, 3-D point measurements were taken to characterize the velocity of the translating tornados. Two vortex cases were simulated and measured:

1)      TVS - a vortex translating for a distance of 4.5 m at a nominal translation speed of about 0.2-0.3 m/s

2)      TVF - a vortex translating for a distance of 4.5 m at a nominal translation speed of about 1-1.2 m/s

The ground surface plate that the measurement devices were attached to was positioned such that the devices measured the span from -20 to 10 cm and 10 to 40 cm (measured from the center of the turntable) for TVS and TVF, respectively. The measurement devices were placed at heights (hp) of 5, 7.5, and 9.5 cm above the ground surface and had an azimuth angle (φ) of 0 degrees. These measurements aim to provide detailed characteristics of the wind field. 

S3. Drone Mounted Anemometer

This specimen was a fully operational Unmanned Aerial Vehicle (UAV) quadcopter. The UAV was equipped with an onboard data acquisition system, a Global Positioning System (GPS), and an anemometer. The anemometer could be oriented in two configurations: parallel and perpendicular to the ground. To enhance GPS accuracy, six Marvelmind robotics Super-Beacons were positioned inside the WindEEE Dome—four placed at 8 cm above the ground and two at ~150 cm. The UAV was tested under various wind conditions at WindEEE, including synoptic wind flow: straight smooth flow, and continuous downburst simulations.

E1. Straight Smooth Flow

This test involved subjecting the UAV described above to Atmospheric Boundary Layer (ABL) flow at three different nominal wind speeds. The UAV was manually piloted, and quasi-stationary measurements were taken at 18 locations, covering three x-positions (1–3), three y-positions (A–C), and two z-positions. Additional measurements were recorded while the UAV traversed through the dome along straight-line paths that passed through the stationary measurement locations—for example, moving from C3, past C2, and then to C1.

E2. Downburst Wind

This test subjected the UAV to a downburst with or without ABL wind. Unlike the downburst winds in S1.E3 or S4.E3, which involved a sudden release of flow, this downburst was a continuous flow. The bell mouth was positioned at the center of the dome, directly over B2. The UAV collected measurements while traversing along three paths: B1 to B2, C3 to B2, and B1 to B3.

S4. Solar Array Pressure Model

This specimen was of an array of solar panels that have span an area of 21 by 2 m built to a scale of  1:20. The model array consisted of 6 panels that measured 105 by 10 cm each and were spaced 20 cm apart from each other. The array model was instrumented with external surface pressure taps, as such the solar panels were  0.6 cm thick allowing for an internal cavity to house the pressure tubing. The angle of attack (δ) of each solar panel in the array could be adjusted for positive or negative 30 degrees. The specimen was tested under the synoptic and non-synoptic wind flow simulations at WindEEE. The position, radial distance from turntable centre (rm) and azimuth angle (φ), varied between the various experiments outlined below.

E1. Straight Wind Load

This test involved the solar array model described above subjected to ABL flow of four different nominal wind speeds. The model positioned at the center of the dome and facing the 60-fan wall (rm=0 m, φ=0°). Both solar panel model angles (δ=±30°) were tested.

E2. BORA Wind Load

This test involved the solar array model described above subjected to BORA wind with gust speed ratio of 2:1, and gust duration ratios of 2:1 with and without roughness elements. The model positioned at the center of the dome (rm=0 m) with seven orientations (φ =0:15:90°) for both solar panel model angles (δ=±30°). The field measurement simulations were conducted with the model positioned at the center of the dome and facing the 60-fan wall (rm=0 m, φ=0°) for both solar panel model angles (δ=±30°).

E3. Downburst Wind Load

This test involved the solar array model described above subjected to downburst with or without ABL wind. The model was positioned at rm=1.35 m and φ=180°, for both solar panel model angles (δ=±30°). The bell mouth was moved to four locations to achieve R/D values of 0.42, 0.70, 1.00, 1.13 m, where D is the jet diameter (D=3.2 m). Two other model positions tested, with R/D=1, were at φ=205° and φ=235°  for both δ=±30°.

E4. Tornado Wind Load

This test involved the solar array model described above, subjected to a slow and fast translating tornado-like vortex flow. For the fast translating tornado, the model was positioned at rm=0.6 m, and with the model directed towards the initial position of the tornado, for δ=-30°. Whereas for the slow translating tornado, the model was positioned at rm=0 m.