How to choose photovoltaic connectors?
Photovoltaic connector, also known as MC connector. In a photovoltaic system, connectors account for a small proportion, but many links need to be used, such as junction boxes, combiner boxes, cable connections between components and inverters. Many construction workers do not know enough about the connector, and there are many failures in the power station due to the problem of the connector. Another report "Review and Analysis of Factors Affecting Photovoltaic Power Generation" released by "solar bankability" in July 2016 showed the impact on the TOP20 power stations. Among the factors, the loss of power generation caused by connector damage or burnout ranks second.
In addition to the quality of the connector itself, another very important reason for the burning of the photovoltaic connector is that the construction was not done properly, which caused the virtual connection of the connector, which caused the DC side to arc, and then caused a fire. The problems caused by the connector include: increased contact resistance, heat generation of the connector, shortened service life, burnout of the connector, power failure of the string, failure of the junction box, and leakage of components, which cause the system to fail to work normally and affect the power generation efficiency.
In the entire photovoltaic system, the DC side voltage is usually as high as 600-1000V. Once the joints of the photovoltaic modules are loosened and the contact is poor, it is very easy to cause the phenomenon of DC arcing. DC arcing will cause the temperature of the contact part to rise sharply, and the continuous arc will produce a high temperature of 1000-3000 ℃, and accompanied by high temperature cannibalization of the surrounding devices. The lighter case will fuse the insurance and cables, the more severe case will burn the equipment and cause a fire.
The improper crimping of photovoltaic connectors is mainly due to the difference of on-site tools and operating experience, resulting in poor crimping quality. The main problem is that the cable copper wire is bent, some of the copper wires are not crimped in and the crimped part is the cable insulation layer.
After the string is completed, connect to the PV terminal of the inverter. Try to use the original photovoltaic connector of the inverter, because this is matched with the PV terminal on the inverter. If it is correctly crimped, it can be a good match. The contact resistance is low, the heat generation is small, and the temperature is lower, and the operation is more reliable and safe. For this problem, it is recommended that qualified installers can purchase professional tools, and provide corresponding training for on-site installers, and establish a random inspection mechanism.
TO sum up
Photovoltaic connector is a very important part of the photovoltaic system. It should attract enough attention. In the process of product selection and construction, the following points should be paid attention to:
1. Use domestic and foreign famous brand products with reliable quality.
2. Products from different manufacturers cannot be mixed together, and the products may not match.
3. Use professional wire stripping pliers and crimping pliers. Unprofessional tools cause poor crimping. For example, part of the copper wire is cut, some of the copper wire is not crimped in, and is crimped to the insulating layer by mistake, and the crimping force is too small or too large.
4. After the connector and the cable are connected, check it. Under normal circumstances, the resistance is zero and it will not break if you pull it hard with both hands.