Photovoltaic connectors that cannot be ignored
1. Performance requirements of photovoltaic connectors
So what are the performance requirements of photovoltaic connectors?
First, the photovoltaic connector should be well conductive, and the contact resistance should not be greater than 0.35 milliohms.
Second, it needs to have sufficient safety performance to ensure the safety performance of solar cell modules. The environment and climate in which solar energy equipment is used are sometimes in very bad weather and environment. Therefore, it must have waterproof, high temperature, corrosion resistance, high insulation and other properties, and the protection level should reach IP68.
Third, the structure of the solar connector should be firm and reliable, and the connection force of the male and female connectors should not be less than 80N. For the MC4 connector connected to a 4mm² cable, when carrying a current of 39A, the temperature should not exceed the upper limit temperature of 105 degrees. MC4/H4 connectors are single-core connectors with male and female headers, which have many advantages such as good sealing, convenient connection, convenient maintenance and maintenance.
2. Precautions for installation of photovoltaic connectors
The selection of the plug should pay attention to the product quality, including the size of the internal metal conductor, the material thickness, elasticity and coating should meet the ability to carry large current and good contact, the plastic of the plug shell should ensure that the surface is smooth without cracks, and the interface is sealed good. When installing the component connector, avoid exposure to sunlight and rain, so as to avoid aging of the connector, corrosion of the internal connector and cable, increase in contact resistance, or even ignition, resulting in a decrease in system efficiency or a fire accident.
The installation of photovoltaic connectors, the crimping link is the top priority, and professional crimping tools should be used. Before the construction of the photovoltaic power station, the relevant engineering installers should be trained in crimping operation.
With the development of photovoltaic cell technology, the capacity of a single photovoltaic module is also increasing, and the string current is also gradually increasing. Although theoretically the design carrying current of the MC4/H4 connector is sufficient to meet the requirements of these large-capacity modules, but Due to various reasons, in recent years, many photovoltaic power stations have experienced more and more accidents in which the connectors are melted, burned, and even lead to the burning of combiner boxes and inverters. Figure 5, Figure 6, Figure 7.
As we all know, in a 100kWp photovoltaic power station, there are usually 600-1000 such connectors, and their working states such as contact resistance are very important to the normal operation of the photovoltaic power station. The poor working condition of the connector will affect the increase of the internal resistance of the DC side, which will lead to a decrease in the power generation efficiency of the power station. In the worst case, the poor contact will cause the connector to heat up or even burn the connector, which will lead to the burning of the combiner box and the inverter (Figure 7)., and even more serious can lead to the occurrence of large-scale fires.
Component connectors, connector plug-ins connected to combiner boxes and string inverters are where faults occur frequently. Although the connector is small, it is very important in the photovoltaic power generation system. Especially in the operation and maintenance process after the completion of the power station, it is necessary to pay attention to its operation status, and to regularly check the heating phenomenon of the connection plug to ensure that there is no abnormality and normal operation.