1.Common connection types of photovoltaic steel columns: Single-layer roof distributed power stations mainly use reserved steel columns and modified steel columns.

Reserved steel columns are pre-welded to the main structure's beams and columns during roof construction, serving as a foundation for later photovoltaic installation. This approach, common in newly built factories, integrates vapor barriers, insulation, fireproof, and waterproof layers after the columns are installed.

Modified steel columns adapt existing single-layer roofs into distributed solar power stations. This method is common in completed factories, enabling secondary roof construction for photovoltaic power generation during later stages of production or operation.

Photovoltaic system steel columns for single-layer roofs are categorized by connection type: welding, bonding, or screw connection. This applies to both reserved and modified distributed photovoltaic power stations.

Welding connection involves attaching the photovoltaic steel column to the main structural steel beam or column. Placement depends on the layout of the structural beams, photovoltaic components, and roof features like skylights and ventilation, ensuring compatibility with the roof's design and facilities.

Adhesive connection saves space and offers economic benefits. It’s commonly used for structural reinforcement, such as bonding photovoltaic steel columns to corrugated steel plates in single-layer roof projects. This method was utilized in early distributed photovoltaic projects by the 11th Institute of Information Industry Electronics.

Adhesive connection saves space and is cost-effective. In GAC Honda Zengcheng Factory’s early single-layer roof photovoltaic project, steel columns were screw-fixed to roof purlins, and waterproof membranes were hot-air welded to fit the columns. This method avoided large-surface openings and steel plate cutting, ensuring structural integrity.

2.Welding is the most common and reliable connection for photovoltaic steel columns. Adhesive and screw connections were mainly used in earlier projects. This article highlights the structure, parameter node waterproof treatment, and project applications of photovoltaic steel column welding connections for enhanced reliability and performance.

2.1.Table 1 lists the main components of photovoltaic steel columns connected by welding, while Figure 4 illustrates their structure. Welding ensures reliable connections, improving waterproof treatment and performance in photovoltaic projects.

Table 1: Main materials of photovoltaic steel columns with welding connection

2.2. Waterproof treatment of photovoltaic steel column nodes connected by welding

If the photovoltaic steel column is installed after the roof waterproof structure, the waterproof and insulation layers must be cut, along with the corrugated steel plate. Typical cutting size is 350mmx350mm, but larger insulation thickness may require bigger openings or welding from inside the roof for sufficient space.

After welding the photovoltaic steel column and main structural steel beam, restore the roof steel plate. Seal the joints between the corrugated steel plate and steel column with weather-resistant silicone, then fill the insulation layer using cut insulation material for proper restoration.

After welding the photovoltaic steel column and main structural steel beam, restore the roof steel plate. Use a homogeneous H-type TPO membrane for detailed nodes, hot-air weld it tightly to the column and roof waterproof layer, then seal with a closing hoop and sealant for integrated waterproofing.

3 .Technical advantages of welding photovoltaic steel columns

3.1 Support and pressure resistance

1) After welding the photovoltaic steel column and main structural steel beam, restore the roof steel plate. Use a durable H-type TPO membrane for detailed nodes, hot-air weld it tightly to the column and roof waterproof layer, then seal with a closing hoop and sealant for integrated waterproofing.

2) After welding the steel column and main structural steel beam, restore the roof steel plate. Use durable H-type TPO membrane for detailed nodes, hot-air weld it tightly to the column and roof waterproof layer, ensuring stability and load resistance, then seal with a closing hoop and sealant for integrated waterproofing.

3.2 Ability to resist natural factors

1)Wind resistance:The strength of steel columns enables them to cope with strong winds and other extreme climatic conditions.In areas with strong winds, photovoltaic modules often face challenges such as wind pressure and airflow,and steel columns can ensure the stable installation of photovoltaic systems and avoid displacement or damage to the system caused by wind.

2)  Snow and rain resistance:In areas with heavy snow or frequent rainstorms,the strong support and weather resistance of steel columns can prevent the photovoltaic system from tilting or collapsing due to the heavy pressure of snow or the impact of rainstorms.Especially in areas with high snow accumulation,steel columns have sufficient compressive strength to bear the weight of snow and ensure the long-term stable operation of the system.

3) Adaptability to various climatic conditions:Due to the corrosion resistance and weather resistance of steel columns,they are suitable for various climatic conditions,from hot and dry to cold and humid environments,which can effectively extend the service life of the roof and its photovoltaic system and maintain its stable operation.

3.3 Photovoltaic module angle adjustment

1) Flexible angle adjustment:The steel column design allows the tilt angle of the photovoltaic module to be adjusted according to specific needs during installation.The angle adjustment not only helps the photovoltaic system to achieve the optimal light reception in different geographical locations and seasonal changes,but also can further improve the power generation efficiency according to the changes in light intensity and sunshine time.

2) Implementation of dynamic angle adjustment:Due to the high load-bearing capacity of the steel column,a slightly heavier angle adjustment tracking device can be equipped when necessary.Through dynamic adjustment,the photovoltaic module can always face the most favorable solar radiation angle.For systems that pursue high power generation efficiency,flexible angle adjustment provides higher operability.

3) Adjusting the photovoltaic module's angle improves power generation efficiency, especially in regions with significant seasonal solar angle changes. This maximizes annual energy output by enabling efficient solar absorption and conversion. The durable H-type TPO membrane ensures waterproofing, corrosion resistance, and longevity under heavy snow and diverse climates.