Meeting Marine Challenges: Design Innovation and Application of QC Solar's Waterproof Junction Boxes on the Sea Surface for Photovoltaics

一、Background
Marine photovoltaics play a crucial role in renewable energy. In recent years, offshore photovoltaic power stations have attracted significant attention due to their huge potential. The International Energy Agency (IEA) predicts that their installed capacity will increase remarkably by 2030. However, the harsh offshore environment poses a severe challenge to the stability of photovoltaic systems. As a core component of offshore power stations, the waterproof junction box for photovoltaics on the sea surface is essential for ensuring the safety and reliability of electrical connections. Therefore, the design of the waterproof junction box for photovoltaics on the sea surface must adapt to the harsh marine environment and possess durability, including the ability to resist salt spray, ultraviolet rays, temperature fluctuations and wave impacts, so as to ensure the continuity of power transmission and the reliability of the entire system.

二、Introduction to the Waterproof Junction Box for Photovoltaics on the Sea Surface

In response to the current R&D requirements in the offshore photovoltaic field, QC Solar (301278.sz) has launched a waterproof junction box on the sea surface (Figure 1). The outer shell of this product is made of PPO material. Its internal structure design combines the S-shaped pouring colloid water-blocking baffle technology and ingeniously integrates it with the hollowed-out bottom design. Externally, the cables are connected through a waterproof rear cover, and it is equipped with an M-shaped integrally molded sealing upper cover, jointly constructing a powerful waterproof barrier.

In practical applications, the sealing of conventional junction boxes usually depends on the internal pouring of sealant. However, in the marine environment, a single sealing design is difficult to cope with. Therefore, the design of QC Solar's sea surface junction box takes into account both sealing and the convenience of installation and maintenance, reducing the complexity and risks of offshore operations. With a modular design, it can quickly replace components, cutting down maintenance costs and time.

三、 Advantages of the Product
3.1 Innovation in the Waterproof Design of the Upper Cover
As shown in Figure 3.1: The clearance fit of the upper cover of traditional waterproof junction boxes tends to cause seawater accumulation and increases the risk of seal failure. QC Solar's sea surface waterproof junction box adopts an innovative M-shaped sealing ring upper cover, which effectively blocks seawater, keeps the interior dry and provides excellent waterproof protection.

3.2 Breakthrough in Internal Waterproof Technology
As shown in Figure 3.2: Traditional waterproof junction boxes usually adopt a vertical glue-pouring sealing method, which is difficult to resist the long-term corrosion and penetration of seawater. However, QC Solar's sea surface waterproof junction box adopts a unique S-shaped bilateral glue-pouring sealing technology, extending the path for water vapor to enter. Combined with the M-shaped sealing ring and S-shaped dual structure, its waterproof ability is significantly enhanced.

3.3 Optimization of the External Waterproof Structure
As shown in Figure 3.3: Traditional waterproof junction boxes use ultrasonic buckles to fix the cables and the box body, but this method has gaps and is prone to the accumulation of solid salt crystals caused by seawater, reducing the waterproof performance. QC Solar's sea surface waterproof junction box uses multiple threads, internal claws and plugs to tighten and fix, and is locked by the rear end anti-backlash after assembly, forming a longer protective and water-blocking area and effectively preventing the intrusion of seawater.

3.4 Outstanding Performance in Waterproof Properties
The internal design of QC Solar's sea surface waterproof junction box (see Figure 3.4) adopts the S-shaped glue-pouring water-blocking track, significantly enhancing its waterproof penetration performance. Paired with the M-shaped integrally sealed upper cover (see Figure 3.5), a dual waterproof barrier is formed (see Figure 3.6). Externally, the cables are fixed by combining nuts, claws and plugs (see Figure 3.7), ensuring both the fixing strength and strengthening the waterproof performance.

四. Application Scenarios:
4.1  Offshore Fixed Photovoltaic Systems
4.2  Floating Photovoltaic Systems
4.3  Fishery-Photovoltaic Complementary Projects
4.4  Salt Pans and Coastal Aquaculture Areas
4.5  Land-based Special Non-glue-pouring Scenarios