2.1. Loads

The maximum wind speed for the Bra§ov region is 30 m/s resulting a maximum wind pressure pm = 580 N/m2 [3] and a maximum wind force Wmax = 580 N on the 1 m2 surface of a panel. The wind direction can be considered towards the front of the panel (fig. 2, a. c) or towards the back of the panel (fig. 2, d. f). There can be considered different assumptions on the distribution of the wind pressure on the panels:

• Uniform pressure [3], corresponding to the bigger wind force (fig. 2, a, d);

• Trapezoidal distribution, approximating the distribution presented in [4], reversed for opposite wind direction (fig. 2, b, e);

• Triangular distribution, following the possible distribution presented in [5], reversed for opposite wind direction (fig. 2, c, f).

For all six wind load cases presented in fig. 2, the load can be reduced to a single wind force W and a moment M, placed on the axis of the panel with values according to Table 1.

Snow loads on sloped panels decrease as the tilt angles and slopes increase. Most PV or thermal collectors have glass surfaces that help the snow-shedding process. Since the tilt angles of a tracker during snow period are relatively big, there is a very small chance of snow load on panel. It can be neglected for Bra§ov region and it will not be considered in this paper.

The weight of the panel together with all the parts (frame) directly attached to the panel is G = 250N. The weight of the other parts is not considered for the preliminary calculus.

The seismic load is critical in earthquake-prone regions and the procedure for designing for seismic loads is standardized, mostly depending on the characteristics of the region. In this paper, the seismic load is not considered.