With more and more applications, the scale of power stations is getting larger and larger. In recent years, the new type of photovoltaic power generation, which is called "fishery and light complementation," has also begun to be applied in the eastern region. The upper layer is used for photovoltaic power generation and the lower layer is used for aquaculture.
As long as the three-dimensional arrangement of photovoltaic panel supports above the water surface and along the banks of the fish ponds, it not only saves land, increases the economic value per unit area of ​​land, but also does not affect aquaculture at the same time as generating electricity. Complementary" features.
However, compared with ordinary large-scale ground power stations, the "fish-to-light complementary" power plant also has certain difficulties. Due to the humidity and high temperature environment, water vapor is easily generated. If water vapor penetrates into the components, the conductivity of the encapsulant (ENC) increases, and the corresponding components The increase of the leakage current will cause polarization of the surface of the module, namely PID effect. Therefore, the power loss caused by the PID effect in the photovoltaic system of the module in a high humidity or high temperature environment, especially a fish-photo complementary photovoltaic system, a coastal photovoltaic system, and a photovoltaic system near the equator is more severe.
PID Effect and Analysis of Formation Cause
PID (Potential Induced Degradation), also known as potential-induced attenuation, is the packaging material of the battery module and the material on the upper surface and the lower surface thereof. Ion migration occurs under the action of a high voltage between the battery chip and its grounded metal frame, resulting in component performance. Decay phenomenon.
External possible causes:
It is easy to occur in a humid environment, and the degree of activity is related to the degree of moisture. At the same time, the degree of contamination of the surface of the module by the conductivity, acidity, alkalinity, and the ion-bearing object is also related to the occurrence of the aforementioned attenuation phenomenon. So far, the formation mechanism is not yet clear, and it is speculated that the metal ions derived from the soda-lime glass are the main current-carrying medium that forms the aforementioned leakage current with the PID effect.
Possible internal reasons:
System aspects: The inverter grounding method and the position of the components in the array determine whether the cells and components are positively or negatively biased. The actual operating conditions and research results of the power station show that if all the components between the entire middle component and the negative output terminal of the inverter are under negative bias, then the PID phenomenon closer to the output component becomes more obvious. While all components in the middle of the middle component and the positive output of the inverter are under positive bias, the PID phenomenon is not obvious.
Components: The influence of environmental conditions, such as humidity, causes leakage currents.
In terms of battery, the uneven sheet resistance due to unevenness in the cell sheet, and the increased sheet resistance used to optimize the cell efficiency will make the cell sheet easier to attenuate, resulting in PID effects.
Therefore, the power loss caused by the PID effect in the photovoltaic system of the high humidity environment, especially in the fish photo-complementary photovoltaic system, the coastal photovoltaic system, and the photovoltaic system near the equator is very severe.
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Cylindrical Battery
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