As a bench technician, one of the biggest problems I identified in the inverters was referring to the connectors MC4. And I'll be sharing some of the cases.
In Brazil, we perceive that many integrators do not have the appropriate tools and experience for the installation of equipment. The biggest consequence of this is the amount of damage to the DC connectors
As we cannot demand the training of technicians for integrator companies, we have received some cases of these problems.
In all our analyses, we were able to identify three situations that lead to this problem:
1. Incorrect equipment for crimping;
2. Opening the DC circuit in load.
3. bad grip on the connector
1: The first and most common, is about of the crimping of cables, we realized that two factors are involved: the lack of correct equipment and the length of the cable available for crimping. Thus, may generate the following damages:
Due to the high current and the low contact area of the connector, the above connector has undergone a heating, deforming it. With this deformation and the load on the output, it began to appear electric arc inside the connectors, contributing even more with the heating. Over time, the inverter may begin to display faults regarding the disconnected string or under voltage in the module.
2: The second case is related to the lack of experience. When a string is reversibly connected, the module enters short. In this case, the ideal is to wait until the night to disconnect the cables and invert the connectors. However, many disconnect the cables with the module in short, thus damaging the connectors.
Due to the high current, and the current characteristic continues to cease in no time, the risk of generating electric arc is large. Being a danger to the life of the installer.
3: Another case is the bad grip on the connector. This allows the connector to move within the cover and as a consequence does not generate the full connection between the terminal of the string to the terminal of the inverter.
Bad grip on the connector prevented the total fitting of the terminals thus generating false contact between them and as a consequence overheating and melting of the cover and electric arc between the terminals. The cover of the terminals should be tightened to the end of the thread thus generating total tightening of the terminal the cover and preventing the terminal movement inside the cover.
So, for a perfect operation of all the functionalities of the SUN2000, it is necessary to pay attention to the installation of the inverter, the crimping of the terminals, polarity of the strings, tightening of the connectors, quality of the installation, something that is not possible Identify in a remote monitoring.
Thank you.
Rafael Guilherme Lange.
