Influence of Salt Spray and High Humidity Environments on Solar PV Systems

The working environment of a photovoltaic (PV) plant is quite complex. Extreme weather conditions such as high or low temperatures, humidity, salt spray, heavy sand, and other harsh environments can test the PV system’s reliability and environmental adaptability. Moreover, an increasing number of PV plants are being built over water, in the desert, and in coastal areas.

Two to three years after the projects are in operation, these extreme environments can severely affect equipment such as the distribution box, mounting structures, and inverters.

This article analyzes the impact of salt spray and high humidity environments on solar plants’ operation and highlights some solutions.

1

The impact of salt spray and high humidity environment 


Salt sprays contain a significant amount of chloride ions, which can easily penetrate the protective layer of a metal surface and causing an electrochemical reaction with the contact metal leading to product failure.

Solar projects built along the coast are susceptible to the effects of high salinity and humid air. The external salt spray particles and humid air will affect the components, cables (especially grounding cables), metal brackets, inverters, and distribution boxes.

High temperature and high humidity environments will also affect the PV system, especially with large temperature differences, such as beaches, mountains, and other areas, where water vapor evaporates and condenses. It easily causes condensation inside the equipment resulting in internal moisture leading to flashover accidents.

High salt spray and intense humidity easily corrode exposed conductors, raising impedance leading to poor contact.

Figure 1 - Corroded PV terminals

Figure 1: Corroded PV terminals

Figure 2 - Corroded PV panel and metal mounting equipment

Figure 2: Corroded PV panel and metal mounting equipment

Long-term accumulation of salt mist and water vapor in the distribution box, terminal or inverter, will corrode the equipment’s internal structure and damage it.

Figure 3 - Corroded PCB boards and components inside the inverter

Figure 3: Corroded PCB boards and components inside the inverter

Figure 4 - Corroded PE cable and grid box interior

Figure 4: Corroded PE cable and grid box interior

Prevention

The equipment needs higher protection and high anti-corrosion levels – especially inverters and distribution boxes deployed in high salt spray or high humidity areas. It is recommended to use inverters with IP65 protection or higher to effectively prevent external moisture from entering the equipment. Meanwhile, the distribution box needs to be galvanized and sprayed with anti-corrosion paint and must be 100% airtight.

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In addition, the inverter’s printed circuit board (PCD) and electronic components need to have film coating, glue, or protective paint to safeguard the circuit board from moisture, salt spray, and mildew.

3

The inverter needs to pass temperature, humidity, and corrosion resistance tests. Developers need to ensure relevant certification for the same in their areas of operation.

4

Developers also need to pay attention to products such as cables, metal brackets, and combiner boxes. Only PV products and mounting structures treated with anti-corrosion products must be deployed. Similarly, the metal parts of the AC/DC/PE cables should not be exposed to the air.

Meanwhile, wiring terminals have to be shielded and fitted to avoid contact with metal surfaces.

5

Protective treatment during installation and construction

PV, PE, and AC cables need to be placed in PVC pipes or buried in the ground to protect them from the effects of abrasion and salt spray.

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The metal bracket and grounding grid metal need to be painted with anti-corrosion paint, galvanized, inspected, and repaired regularly to prevent corrosion.

7

Special attention should be paid while using aluminum or zinc bolts to connect stainless plates to prevent electrochemical corrosion caused by contact between different metals. Plastic gaskets can be added to isolate the two metals and prevent contact corrosion.

8

The combiner or grid box needs fire-resistant mud at its inlet and outlet to improve protection and prevent water vapor from entering.

9

Salt spray and high humidity environments can corrode solar panels and seriously affect the project’s safety, reliability, and long-term operation. Particular attention should be paid to equipment selection, construction, and operation and maintenance to improve the operational stability of the PV project and reduce system errors.

This article is sponsored by solar inverter manufacturer Ginlong Technologies.

 

Image credit: Solis