The load calculation for photovoltaic mounting systems must comprehensively consider the following factors, specifically including:

Self-weight load

Includes the weight of photovoltaic modules, brackets, connectors, and accessories. For example, the weight of modules is approximately 20 kg/m², the self-weight of PV brackets is approximately 10-15 kg/m², and the total system weight does not exceed 100 kg/m². The total self-weight must be calculated based on the materials and dimensions during the design phase.

Wind load

Calculated based on the wind speed, wind direction, wind pressure height variation coefficient, and shape coefficient of the installation site. For example, in Wuhan, Hubei Province, the basic wind pressure for a 10-year return period is 0.35 kN/m², and for a 50-year return period, it is 0.45 kN/m². In areas with strong winds, special attention should be paid to lateral stability, which can be achieved by adding diagonal braces or windbreak walls to reduce the wind load coefficient.

Snow load:

Snowfall, snow density, and support slope directly impact snow load. For example, snowy areas should be designed for a 50-year return period. The snow load calculation formula is: slope coefficient × unit snow mass × snow accumulation. In some areas, the snow load can be set at 70% to accommodate short-term snow accumulation.

Seismic loads

Horizontal seismic forces must be considered in seismic zones. These forces are typically smaller than wind pressures but must meet regulatory requirements (e.g., GB 50009-2012). Load combinations must include the combined effects of seismic and wind loads.

Live loads

These include lifting loads during the construction phase, as well as loads on maintenance personnel and equipment. For example, the construction load for a color-coated steel tile roof is approximately 0.15 kN/㎡, and for a concrete roof it is approximately 0.45 kN/㎡. Temporary loads during construction must be considered during design.

Special Loads

Occasional loads: These can occur due to extreme weather conditions (windstorms, hail) or vandalism.

Maintenance loads: Rooftop PV systems must meet a live load requirement of at least 2.0 kN/m².

Safety Factor and Code Requirements

The design must combine loads for both the ultimate and serviceability limit states, taking the most unfavorable combination. The safety factor is typically 1.2-1.5. Load calculations must comply with standards such as the Code for Loads on Building Structures (GB 50009-2012).

Environmental and geological factors

The bearing capacity of the foundation, soil type, and construction conditions influence foundation design. For example, shallow reinforced concrete foundations must meet requirements for resistance to slip, overturning, and uplift.

In summary, the load calculation of photovoltaic supports needs to be combined with local meteorological data, material properties and regulatory requirements, and multi-working condition combination analysis should be used to ensure structural safety and stability.