What to do in case of untimely circuit breaking on an installation equipped with Dualsun panels?

Frequent tripping in an installation can be caused by excessive leakage currents, which trigger the residual current device (RCD). Leakage currents can have several origins, such as parasitic capacitance, installation errors, or insulation faults.  

According to the Agence Qualité Construction, the method for detecting frequent RCD tripping should be based on the analysis of inverter monitoring data. It is also essential to check the entire wiring of the installation, as well as the grounding of the inverter and panels.  

All Dualsun panels are certified under IEC 61215-61730, which includes the following tests performed multiple times during the certification process:  

• MQT03/MST16 - Insulation Test (Dielectric Test):  

 "Determine whether the PV module is sufficiently insulated between current-carrying parts and the frame or other externally accessible components. The maximum test voltage must be 2000V, which is more than four times the system's maximum voltage."  

This test is performed on every module during production.  

• MQT15/MST17 - Wet Leakage Current Test:  

"Evaluate the module's insulation under wet conditions and verify that rain, fog, dew, or melting snow does not enter the active parts of the module's circuits, where it could cause corrosion, a ground fault, or a safety hazard."  

This test is performed randomly on modules.  

• MST13 - Continuity Test for Equipotential Bonding:  
  "Demonstrate that there is a conductive path between all exposed conductive surfaces of the module, ensuring that these surfaces can be properly connected to the ground in a PV system."  

This test is performed on every module during production.  

• MST11 - Accessibility Test:

  "Determine whether uninsulated electrical connections pose a shock risk to personnel."  

  This test is performed only for panel certification.  

Given the insulation-related tests, it is highly unlikely that frequent tripping issues are caused by a defect in Dualsun panels. Based on experience, these issues can often be resolved by ensuring that the installation complies with standards, as well as Dualsun's recommendations and those of inverter manufacturers.  

A photovoltaic (PV) array behaves like a capacitor between the ground and the phase. This generates capacitive leakage currents, which are harmless. 

In a TT neutral system, such as in France, a transformerless string inverter will transmit part of the grid's voltage amplitude into the DC circuit of the panels. Due to its electrical capacitance, the PV array then generates an alternating voltage. This creates a current flowing to the ground, known as leakage current.  

This leakage current combines with the fault current to create the residual differential current. It is this current that is detected by the installation's RCD and can cause it to trip.  

Only the fault current, caused by an electrical insulation fault, is dangerous to people.  

Therefore, as long as the panels are properly grounded, this leakage current is not dangerous to people but may trigger an RCD.  

To prevent RCD tripping, several solutions can be implemented: 

1. install a 300mA RCD (residual current device) (allowed under Amendment A5 of the NF C 15-100 standard, provided that the grounding resistance is less than or equal to 167 ohms and no power outlets are installed on the AC side of the PV system). 

2. Use inverters with transformers: The galvanic isolation between the panels and the electrical circuit prevents the appearance of unwanted AC currents that generate leakage currents.  

The SPRING4 has a higher capacitance than a FLASH panel due to the presence of the conductive heat exchanger near the cells. Its average measured capacitance is 18nF.  

Therefore, it is even more important to pay attention to this issue in installations containing SPRING4 panels.