In the article “Are generic MC4 connectors compatible?” we address the issue of compatibility between MC4 type connectors found on the market.
Recalling the history of this subject a little: the solar market has already encountered different connector standards for modules and strings in the past.
As happens in many markets, with different products, connectors have undergone an evolution over time.
At a certain point the MC4 connector, created by dusty, ended up gaining worldwide acceptance, starting with the European market, and became the global standard in photovoltaic systems.
Several manufacturers, including major market participants, started to offer similar connectors, supposedly compatible with each other.
Although they all adopt a similar design, compatibility cannot be fully guaranteed and there are risks when mixing connectors from different manufacturers in the same project.
As mentioned in the article Are generic MC4 connectors compatible?, although it is not recommended to combine connectors from different sources, it is often difficult to maintain standardization in projects.
The general rule that must be followed, if full standardization is not possible, is to look for connectors from reputable manufacturers, leaving aside the generic connectors that flood the market.
The quality and expertise of large manufacturers are important, especially when we are talking about electrical connectors, which are an essential safety factor and represent a tiny fraction of the overall cost of a photovoltaic installation.
In summary, there are two important aspects when we talk about connectors for photovoltaic systems: compatibility between connectors from different manufacturers and quality.
A case of connector (in)compatibility
Below we will report a curious case of connector incompatibility that occurred in the Brazilian market. The information was extracted from a report provided by Stäubli, prepared in March 2018. The customer alleged that the Stäubli MC4 connectors (model 32.0017P0001-UR) presented poor fixation of the electrical terminal next to the plastic housing.
As you know, when inserting the electrical terminal of the MC4 connector into the plastic receptacle, it is fixed with a characteristic “click”. In this case, the customer reported that the click was not occurring and the terminal could be easily removed by pulling the cable.
According to the report signed by application engineer Daniel Franzini, from Staübli, the analysis of some units of defective parts made it possible to verify the defect alleged by the customer, with the release of the contact when pulling the cable.
The positioning of the contact was also checked after its installation, noting irregular assembly: the calibrator penetrates more than expected (figure below, on the left), preventing the view of the white band that certifies correct assembly (figure below, on the right) .
An inspection of the metal terminals also revealed that there were terminals of unknown origin mixed in with original terminals. The origin of this fact is not known, but the important finding is about the incompatibility of these artifacts.
In Figures 4 and 5, the discrepancies between metal parts from different manufacturers can be seen very clearly.
The discrepancies observed in the previous figures were reported to Stäubli headquarters in Allschwil, Switzerland, which confirmed the use of Stäubli housings with metal contacts of unknown origin. As a conclusion of the materials analysis, it was observed that the generic connectors, of unknown origin, were absolutely incompatible with the original MC4 connectors.
The incompatibility existed not only in the mechanical aspect, confirmed by the terminal not locking inside the plastic receptacle, but there were also structural and dimensional discrepancies between the metal parts, which could lead to inadequate electrical contacts, putting the photovoltaic installation at risk.
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An answer
Good afternoon. It's a good article, but the figures numbered 1 to 5 do not appear on this page.