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Analysis of the problem and solution for residential photovoltaic against extreme weather (South China coastal area)

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Analysis of the problem and solution for residential photovoltaic against extreme weather (South China coastal area)

When constructing photovoltaic power plants in South China coastal areas, the impact of extreme weather such as typhoons and rainstorms needs to be considered. Not only does it require strict quality control in the project design stage, but also the subsequent operation and maintenance stage.

1. Typhoon

The main impact of typhoon on residential photovoltaic system is to blow up and overturn the photovoltaic panels. If the design is unreasonable, it may cause the entire roof to be lifted, which will not only cause economic losses but also poses a threat to the personal safety of residents. In August 2018, the photovoltaic modules installed on a household’s roof in Zherong County, Fujian Province were overturned by a typhoon and 38 photovoltaic panels were damaged. Fortunately, there were no casualties. Afterwards, the component manufacturer stated that the accident was as a result of the dealer’s improper installation. The photovoltaic brackets were not locked on the cement foundation in accordance with the regulations, but were locked on the remaining stone piers of the residents’ decoration. It remains clear that high quality of photovoltaic modules as well as standard installation are both indispensable.

 

Figure 1: The overturned photovoltaic panels in a resident’s home in Zherong County, Fujian Province

In fact, the wind resistance of photovoltaic panels is mostly determined by photovoltaic brackets. The brackets are usually made of aluminum alloy, carbon steel and stainless steel. There are two common connection methods between brackets: welding and assembly. Since the welding points are not artistic and they are easy to rust, assembly connections are now mostly used. This connection process uses channel steel as the main supporting layout component, which is not only easy to assemble but also has good durability. Theoretically, the maximum wind resistance of the brackets is 216 km/h and the maximum wind resistance of the tracking brackets is approximately 150 km/h (greater than 13 typhoons). Besides the solid support, the location of the foundation is also very important. Currently, residential photovoltaic power stations are mainly installed on inclined as well as flat roofs. During installation, issues such as installation location, installation orientation, installation angle, load requirements, arrangement, and spacing all need to be considered. The counterweight of the photovoltaic system is generally a cement foundation. The development of cement foundation must fully consider the load of the building as well as meet the requirements for wind and snow resistance.

Zinc-magnesium-aluminum alloy assembled photovoltaic bracket  

 

Figure 2: Zinc-magnesium-aluminum alloy assembled photovoltaic bracket

2.Rainstorm

The rainstorm itself will not have a negative impact on the integrity of the residential photovoltaic systems, because residential photovoltaic inverters are generally IP5 waterproof (water washing will not cause any damage to the product).  In order to better prevent water leakage, the gaps between panels should not be sealed, usually butyl aluminum foil tape is used horizontally and waterproof tape is used vertically. This way, rainfall will not threaten the photovoltaic system and buildings.  Rainfall washes away the dust and impurities accumulated on the surface of the photovoltaic panels, which then helps improve the efficiency of the system.

 

Figure 3: Roof photovoltaic panel sealed with waterproof tape and butyl aluminum foil tape

However, after the rainstorm, the soaking of rainwater is a big test for residential photovoltaic system. For panels installed on sloping roofs, there is generally no excessive accumulation of water due to the strong drainage capacity of the roofs. Whereas, for the photovoltaic system installed on flat roofs, the solar panels may be soaked in rainwater on encountering excessive rainfall due to their low brackets. This damages the power supply system and there may be a risk of electric shock if someone touches it.

 

Figure 4: Solar photovoltaic panels laid on the sloping roof

Therefore, in order to prevent excessive accumulation of water on the flat roof, a set of drainage systems can be added before the onset of heavy rain to effectively drain the water. During the inspection after rain, do not directly touch the connection part of the inverter, photovoltaic module, and power supply cable with naked hands. Also, be sure to wear rubber gloves and rubber boots.

It is clear that extreme weather will not have a serious impact on the home photovoltaic system with regular components and correct installation. After meeting the above requirements, the photovoltaic panel becomes very reliable. Such a system is not only harmless to the building but can also become a roof umbrella. If you would like to know how to choose photovoltaic modules, photovoltaic system installation specifications or other precautions, please contact info@prozparity.com. Prozparity offers you one-stop professional household PV design, installation, Feed-in Tariff application services and maintenance any time.


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