1) Dip design
In order to get as much solar radiation as possible for a solar module in a year, we need to choose the best tilt angle for the solar module.
Discussions on the optimal tilt angle of solar modules have appeared in a number of academic journals in recent years. The area where the street lamp is used is Changsha. According to the data in this design reference [1], the solar cell module bracket inclination angle is 16o.
2) Windproof design
In solar street lighting systems, one of the structural issues that needs to be taken seriously is the wind-resistant design. The wind-resistant design is mainly divided into two large blocks, one is the wind-resistant design of the battery assembly bracket, and the other is the wind-resistant design of the light pole. The following two pieces are separately analyzed. (1) Wind-resistant design of solar module bracket
According to the technical parameters of the battery component manufacturer, the solar cell module can withstand a wind pressure of 2700 Pa. If the wind resistance coefficient is selected to be 27 m/s (equivalent to ten typhoons), according to the non-viscous fluid mechanics, the wind pressure of the battery assembly is only 365 Pa. Therefore, the assembly itself is fully capable of withstanding wind speeds of 27 m/s without damage. Therefore, the key consideration in the design is the connection of the battery assembly bracket to the pole.
In the design of the lamp set system, the connection between the battery assembly bracket and the lamp post is fixedly connected by using a bolt rod.
(2) Windproof design of street light pole
The parameters of the street light are as follows:
Panel inclination A = 16o pole height = 5m
Design selection of the bottom of the lamp post weld width δ = 4mm lamp pole bottom outer diameter = 168mm
The surface of the weld is the damage surface of the pole. The distance from the calculation point P of the lamp-bar damage surface to the resistance moment W to the action line F of the panel subjected to the lamp post is
PQ = [5000+(168+6)/tan16o]× Sin16o = 1545mm=1.545m. Therefore, the moment of action of the wind load on the failure surface of the lamp post is M = F × 1.545.
According to the maximum allowable wind speed of 27m/s design, the basic load of the 2×30W double-lamp solar street light panel is 730N. Consider the safety factor of 1.3, F = 1.3 × 730 = 949N.
Therefore, M = F × 1.545 = 949 × 1.545 = 1466N.m.
According to mathematical derivation, the resistance moment of the toroidal failure surface is W = π × (3r2δ + 3rδ2 + δ3).
In the above formula, r is the inner diameter of the ring, and δ is the width of the ring.
Destructive surface resistance moment W = π × (3r2δ + 3rδ2 + δ3)
=π×(3×842×4+3×84×42+43)= 88768mm3
=88.768×10-6 m3
Stress caused by moment of action of wind load on the failure surface = M/W
= 1466/(88.768×10-6) =16.5×106pa =16.5 Mpa<<215Mpa
Among them, 215 Mpa is the bending strength of Q235 steel.
Therefore, the width of the weld selected by the design meets the requirements, as long as the welding quality can be guaranteed, the wind resistance of the pole is no problem.
