Disconnection of PV systems Fire brigade switch – new: “Cluster” technology for disconnecting large PV systems!

In the area of larger rooftop systems, disconnecting the PV generators either directly at the roof inlet or immediately afterwards is a safety feature of modern PV systems that can no longer be ignored. This is the only way to ensure that in the event of an incident in the building, for example a fire, the PV cables penetrating the building can be disconnected from the power supply.

The Bavarian manufacturer of energy communication technology Q3 ENERGIE GmbH & Co. KG has been offering corresponding switching technology since 2012. The devices are usually planned and installed on a project-specific basis. In addition to the pure switching technology, the switch boxes can also include overvoltage protection or cables can be combined as in a string box and fitted with fuses. The switch-off itself then takes place via a control box. This can also detect a cable break and display the status message of overvoltage protection modules. If required, an additional external emergency stop can be connected, as well as a potential-free contact that signals the system status to a fire alarm control panel, for example.

To simplify cable routing from the control box to the individual roof surfaces, Q3 has now developed a cluster technology. Up to five different roof surfaces can now be approached and switched off with a single control box. In addition to "On and Off", each individual cluster also signals the line status and, if necessary, the functionality of the surge protection. The distance between the control box and an individual cluster can be up to 1,200 meters. In the event of a power failure, all clusters go into a safe state and switch on automatically when the grid is restored. In the event of a switching event, all strings of the entire system are disconnected from the PV generator from the control boxes and are therefore safely de-energized.

The system was recently adapted to the higher module outputs and strings with up to 1,500 V DC at 15 A string current can be switched[addendum: 1,500 V DC at 20 A since July 2025]. The Q3 system is certified in accordance with IEC 60946 and can be individually integrated into a wide range of system types and sizes. Q3 offers regular training courses for planners and installers.