## 5 Study 2: Resilience of Roof-Mounted Solar Panels to High Wind Loads
### Aerodynamic Testing of Photovoltaic Panels on a Gable-Roofed Building  
After the wind testing of the unaltered building model, a total of eighteen PV panels were affixed to the roof, as per the configurations delineated in Figure 9[69]. When scaled down at a ratio of 1.7.5, these panels possessed dimensions of 203 mm in width and 447 mm in length. Figure 9: Aerodynamic test model comprising: (**a**) a gabled roof integrated with PV panels (Case 2), (**b**) an active panel equipped with pressure taps affixed onto the roof (tubes precisely aligned with the surface before testing), (**c**) a PV array model featuring an engineered racking system (Case 3), and (**d**) panel configuration enhancements implemented for conclusive testing, entailing gap closure and integration of a leading-edge trim (Case 4). The trim was constructed to a 1.7.5 scale, in concordance with the overall model. The layout of the panels in this investigation was deliberately selected to align with the V2 configuration previously employed in a related study [46]. Given the symmetrical nature of the building layout, merely three panels were equipped with pressure taps, while the remainder served as inert counterparts. The active panels, totalling three, were fabricated from 2-mm thick acrylic sheets, in contrast with the dummy panels, which were formed from plywood sheets. Following their fabrication, the solar panels were securely fastened to the roof through super glue, complemented by precisely dimensioned wooden blocks that ensured an optimal attachment height (see Figure 9a,b). Given the vertical clearance between the roof surface and the panels, pressure taps were strategically positioned along the top and bottom surfaces. Emphasis was placed on corner and edge locations during tap layout design. The bottom surface tap layout aligned tributary areas with those on the upper surface, facilitating net pressure computations. The top surface of the panel featured twenty-four pressure taps, while the bottom surface had eight taps. To mitigate dynamic pressure effects, taps along the bottom surface were oriented at a 45-degree angle (Figure 9b). Conduits for the PV panel taps traversed an aperture in the underlying roof surface and linked to the sensors inside the building. To amass a comprehensive pressure dataset for wind interactions with the panels, the model was subjected to oncoming wind from eight cardinal directions: 0\({}^{\circ}\), 45\({}^{\circ}\), 90\({}^{\circ}\), 135\({}^{\circ}\), 180\({}^{\circ}\), 225\({}^{\circ}\), 270\({}^{\circ}\), and 315\({}^{\circ}\). This selection of wind directions ensures a thorough examination of wind effects on the bare roof and roof with panels in different configurations. The ensuing pressure data were recorded and scrutinized to yield insights into the aerodynamic performance of the roof panels under varying wind conditions. Following the initial two tests (bare roof (Case 1) and roof with panels in the configuration shown in Figure 9a (Case 2)), the investigation progressed by incorporating realistic solar array elements into the model. The initial step involved integrating the array's racking system by affixing 1/2 inch (13 mm) square wooden dowels to the roof surface beneath the panels (Case 3 as shown in Figure 9c). Four rows of racking were affixed to the model. The placement and dimensions of the racking were determined using the UNIRAC design tool and product specifications [72]. Figure 9c depicts the racking securely attached to the roof. The model subsequently underwent its third round of testing with oncoming wind from the same angles as in the second test. To enhance the aerodynamic performance of the PV arrays, the second phase of adjustments entailed minimizing the interspace between the panels. In a standard full-scale array, the inter-panel gap measures 1 inch (25.4 mm), which translates to approximately 0.13 inches (3.4 mm) at a reduced scale of 1:7.5.