Feuerwehrschalter QFire BIG für große PV-Anlagen
Generatornahe Abschaltung mehrerer PV-Strings – projektspezifisch geplant, galvanisch getrennt nach IEC 60947-3.
String-Level Remote DC Disconnection for Large PV Systems
QFire BIG ist eine stringbasierte, fernsteuerbare DC-Trennlösung für gewerbliche und industrielle PV-Anlagen im IEC-Umfeld.
Das System ist für Aufdachanlagen, Industriegebäude, Logistikdächer und komplexe Photovoltaikanlagen ausgelegt, bei denen mehrere PV-Strings, lange DC-Leitungswege oder mehrere Generatorfelder sicher abgeschaltet werden müssen.
Die QFire BIG Schaltboxen werden generatornah installiert und trennen die angeschlossenen PV-Strings galvanisch nach IEC 60947-3. Je nach Projekt können bis zu 24 PV-Strings in einer Schaltbox verarbeitet werden. Die Auslegung erfolgt passend zur Anlage – mit Blick auf Stringanzahl, Systemspannung, Stringstrom, Dachstruktur, Leitungsführung und gewünschtes Abschaltkonzept.
Zusätzlich kann QFire BIG projektspezifisch in ein AC-seitiges Abschaltkonzept eingebunden werden. Über den Statuskontakt der QFire Steuerbox lassen sich externe Komponenten wie NA-Schutz, Wechselrichter-Freigabe oder bauseitige Schützsteuerungen ansteuern. So können DC-seitige Generatorfreischaltung und AC-seitige Abschaltlogik bei großen PV-Anlagen gemeinsam geplant werden.
QFire BIG ist kein Moduloptimierer und keine klassische Rapid-Shutdown-Lösung auf Modulebene. Der Fokus liegt nicht auf Leistungsoptimierung am einzelnen Modul, sondern auf der sicheren DC-Stringabschaltung und Generatorfreischaltung für professionelle PV-Anlagen – zum Beispiel im Brandfall, bei Wartungsarbeiten oder im Serviceeinsatz.
Dank zentraler Steuerbox, projektspezifischen DC-Schaltboxen, der optionalen Clusterlösung und externer Not-Aus-Anbindung lässt sich QFire BIG flexibel in unterschiedlichste Anlagenkonzepte integrieren. Das System eignet sich insbesondere für:
QFire BIG auf einen Blick
| Anwendung | Kundenspezifische Anschlussboxen |
| Funktion | DC-Stringabschaltung / PV-Generatorfreischaltung |
| Trennung | galvanisch nach IEC 60947-3 |
| Systemspannung | bis 1.500 V DC |
| Stringstrom | bis 20 A Isc pro String |
| Stringanzahl | bis 24 PV-Strings pro Schaltbox |
| Erweiterungen | Not-Aus, Schlüsselschalter, Brandmeldeanlage, Statuskontakt, SPD, Sicherungen, Cluster, Einbindung in AC-seitige Abschaltkonzepte |
Large Industrial and Commercial Roofs
Multiple Roof Areas
Expandable PV Projects
Multiple Inverters & MPP Trackers
Complex System Structures
Increased Safety Requirements
The modular system architecture is particularly suitable for complex roof structures, multiple generator fields, and large PV capacities with many strings. Depending on system size, switching units for 2 to 24 strings are available – with system voltages up to 1,500 V DC and up to 20 A per string.
For extensive sites, multiple QFire systems can be controlled together via the QFire Cluster Control Box. This allows central disconnection of multiple buildings or separate generator fields.
Surge protection, external emergency stop buttons, key switches, status contacts, and online monitoring via QFire.LIVE are optionally available.
QFire BIG is a firefighter switch for large PV systems with multiple generator fields, complex roof structures, and high safety requirements.
QFire BIG in PV System Planning
Which PV firefighter switch is suitable for commercial PV systems?
In commercial and industrial PV systems, a simple DC disconnect switch at the inverter is often not sufficient, especially when long DC cable routes, multiple roof areas or specific requirements from the fire safety concept have to be considered. The key points are where the PV strings are disconnected, which voltages and currents are present, and how the shutdown should be triggered in an emergency.
QFire BIG is designed for exactly these types of systems. The switch box is installed close to the PV generator and disconnects the connected PV strings by galvanic isolation according to IEC 60947-3. This allows the DC cables from the switch box towards the inverter to be disconnected in a controlled way – manually via the control box, via external emergency stop or key switches, via a fire alarm system or, depending on the system design, AC-coupled in case of grid failure.
For planners and installers, the important point is this: QFire BIG is not treated as a standard off-the-shelf device, but is configured project-specifically according to the number of strings, roof structure, cable routing, protection concept and required accessories.
What is needed for DC string disconnection in large PV systems?
In large PV systems, DC string disconnection should be considered early in the planning phase. The most relevant factors are the maximum DC system voltage, the short-circuit current per string, the number of strings, the allocation to MPPTs, the cable routes from the PV generator to the inverter and the requirements from the fire safety concept.
QFire BIG is configured precisely for these conditions. Depending on the project, several strings can be combined in one switch box and disconnected close to the generator. Optional components such as surge protection, PV fuses, status contacts, external shutdown points or cluster solutions for multiple roof areas can be integrated.
The aim is not to place as many components as possible somewhere in the system, but to create a clear and serviceable DC structure: traceable string routing, a defined disconnection point, clear status indication and a solution that fits the actual PV system.
How can multiple PV strings be disconnected safely?
Multiple PV strings are best disconnected at the point where they are routed from the generator towards the building or inverter. This is exactly where QFire BIG is used. The switch box is installed close to the generator and disconnects the connected DC string cables by galvanic isolation.
Depending on the configuration, several PV strings can be handled in one QFire BIG switch box. This makes it possible to create a structured shutdown concept even for larger rooftop systems, without having to treat every single string with a separate standalone solution. Operation is carried out centrally via the control box or via integrated external shutdown points.
For large systems with several building sections or roof areas, the shutdown concept can also be planned using cluster technology. This keeps operation clear and manageable, even when the DC structure of the PV system is more complex.
Combining DC and AC shutdown in the system concept
In large PV systems, industrial projects and megawatt installations, the shutdown concept often has to be considered as a complete system. QFire BIG disconnects the PV strings on the DC side close to the generator by galvanic isolation according to IEC 60947-3. In addition, the status contact of the QFire control box can be used project-specifically to integrate external AC-side components – for example a grid and system protection relay, an inverter enable signal or a site-specific contactor control.
This is particularly relevant for large rooftop systems, installations with several inverters, hybrid systems with battery storage or projects with special requirements regarding fire safety, grid connection and operational safety.
More information on combined DC and AC-side shutdown can be found in our technical explanation of QFire PV generator disconnection.
Modular System Design of Generator Disconnection for Large PV Systems and Rooftop Installations
QFire BIG enables galvanic isolation of PV strings between the generator field and inverter. Typical components are:
Separation of control [2] and DC switch boxes [1]
Expandable through additional switch boxes
Integration of fire alarm system and/or external emergency stop button [3]
Central or cluster-based disconnection
The QFire BIG system has a modular design and consists of a central control box, optional cluster control boxes, and DC switch boxes for up to 24 strings per box. The switch boxes are custom-built and can optionally be equipped with surge protection and fuses.
Optional components are:
■ Fire alarm system connection
■ Integrated surge protection
■ Integrated fuses in positive and/or negative pole
■ External emergency stop button
■ Cluster technology for multiple roof areas
■ Online monitoring
■ Delay circuit (time-delayed disconnection of large systems)
In case of disconnection, all strings are galvanically isolated so that the lines from the installation location of the firefighter switch toward the inverter become de-energized.
This separation of control and switching function enables flexible adaptation to system size, roof structure, and safety requirements.
Galvanische Trennung der DC-Strings
Der QFire Feuerwehrschalter trennt im Auslösefall alle angeschlossenen PV-Strings galvanisch und zweipolig nach IEC 60947-3. Dadurch werden Plus- und Minusleiter jedes Strings zuverlässig vom Wechselrichter getrennt – für maximale Sicherheit im Brand- und Einsatzfall.
Klare Abgrenzung zu Motorschalter-Lösungen
Zweipolige Trennung von Plus und Minus
sichere Unterbrechung der DC-Verbindung
DC-seitige Abschaltung direkt am String statt nur netzseitiger Trennung
geeignet für Systemspannungen bis 1.500 V DC und bis zu 20 A pro String
Bei der galvanischen Trennung wird die elektrische Verbindung zwischen PV-Generator und Wechselrichter vollständig unterbrochen. Nach der Auslösung sind die Leitungen ab der QFire-Schaltbox spannungsfrei. Dieses Prinzip reduziert DC-Gefahren im Brandfall deutlich und sorgt für maximale Sicherheit bei Einsatzkräften und Servicepersonal.
Dieses Schaltprinzip erhöht die Sicherheit im Brand- und Einsatzfall erheblich, da gefährliche Gleichspannungen zuverlässig unterbrochen werden. Gleichzeitig ist die galvanische Trennung unabhängig von der Anlagenkonfiguration, der Stringlänge oder der Anzahl der angeschlossenen Generatorfelder wirksam.
QFire BIG control box for large PV systems
Central Control and Coordinated Disconnection of PV Strings
The QFire control box operates with independent system logic. This ensures that the disconnection function remains clearly defined and reliably controllable even with complex system structures, multiple roof areas, or long cable runs.
The control box forms the central control element of the QFire BIG generator disconnection. It handles the complete evaluation logic of incoming control signals and coordinates the control of connected switch boxes. In case of triggering, the control box ensures defined, safe disconnection of all connected DC strings – regardless of number, distance, or system size.
Through the clear separation of control and DC switching function, the electrical structure remains clear and compliant with standards. The control box itself does not switch DC loads but functions as a higher-level logic and interface layer. This makes the system particularly suitable for larger and complex PV systems with multiple generator fields or future expansion requirements.
QFire BIG Firefighter Switch:
Cluster Technology for Large PV Systems
Cluster technology enables central disconnection of multiple generator fields via a common control logic.
QFire BIG cluster control box for central shutdown of distributed generator fields
Additionally: Higher-Level, Star-Configured Disconnection Structure
For large and complex photovoltaic systems with multiple roof areas or generator fields, the cluster control box extends the QFire BIG system with a higher-level, star-configured disconnection structure.
The cluster control box supplements the functions of the QFire BIG generator disconnection for systems with multiple roof areas, halls, building sections, or widely distributed generator fields. It functions as a higher-level distribution and coordination unit and enables star-configured connection of multiple switch boxes or system segments.
The cluster structure allows even large and spatially complex PV systems to be shut down reliably and simultaneously. The shutdown logic remains clearly defined – regardless of the number of connected switch boxes or the overall size of the installation. This makes the QFire BIG firefighter switch system with cluster control box particularly suitable for industrial, commercial and logistics facilities, as well as for projects with future expansion requirements.
Triggering Methods and Interfaces
Plug + Play Installation
QFire BIG switch box for modular DC shutdown with galvanic isolation
For Safe Disconnection Up to 1,500 V DC / 20 A per String
The QFire BIG firefighter switch boxes provide galvanic isolation of the PV strings directly at the generator field. They form the central DC switching function of the system and ensure safe, standards-compliant disconnection of the connected strings during shutdown.
Through the modular design, the switch boxes can be flexibly adapted to different system structures – from small partial generators to large PV systems with multiple roof areas and high string counts.
Each switch box in the system provides galvanic isolation of the connected PV strings directly at the installation location.
Warum ist QFire BIG keine Moduloptimierer- oder Rapid-Shutdown-Lösung?
QFire BIG is not a module optimizer solution and not a conventional module-level rapid shutdown solution. This distinction is important because these systems follow a different technical approach.
Module optimizers, microinverters and MLPE systems operate directly at the individual module or module string and are often associated with power optimization, monitoring or rapid shutdown. QFire BIG is designed differently: the system disconnects PV strings close to the generator via a switch box and is designed for commercial and industrial PV systems with multiple strings, clear cable routing and a defined shutdown concept.
The focus is not on module optimization, but on safe DC string disconnection and PV generator disconnection. QFire BIG disconnects the DC strings by galvanic isolation according to IEC 60947-3 and is integrated into the project-specific system planning.
QFire BIG Firefighter Switch: Project-Specific Instead of Standard Solution
The QFire BIG switch boxes are designed, planned, and manufactured project-specifically. String count, connection technology, protective components, enclosure sizes, and interfaces are individually tailored to the respective system structure.
This creates not an off-the-shelf standard solution, but a technically sound, standards-compliant, and future-proof disconnection solution – Made in Germany.
String Count
■ Switch boxes from 2 to 24 PV strings
■ Flexible string reductions between input and output
Connectors and Connection Variants
■ Standard: MC4-Evo2 from Stäubli
■ Alternatively H4, Sunclix, or terminal technology possible
DC Surge Protection
■ Optional integrated surge protection
■ Standard: Q3 surge protection T1+2 up to 1,500 VDC
■ Alternative surge protection manufacturers available on request
PV Fuses
■ Optional integrated PV fuses
■ In positive and/or negative pole possible
Projektanfrage Feuerwehrschalter QFire BIG
Sie möchten das QFire BIG System projektspezifisch auslegen, technische Details prüfen lassen oder die passende Systemkonfiguration für Ihre Photovoltaikanlage auswählen?
Über das nachfolgende Anfrageformular erfassen wir alle relevanten Projektdaten strukturiert und nachvollziehbar.
Gerne können Sie Verschaltungspläne, Stringpläne oder weitere technische Unterlagen direkt mitsenden. Auf dieser Basis prüfen wir die technischen Rahmenbedingungen, legen das QFire BIG System passend zu Ihrem Projekt aus und stimmen die Komponenten gezielt ab.
Sollten Rückfragen erforderlich sein, melden wir uns bei Ihnen. Andernfalls erhalten Sie direkt ein projektspezifisches Angebot.
Projektanfrage Feuerwehrschalter
Projektbezogene Anfrage zur Auslegung des QFire Systems. Auswahl der Komponenten und Erstellung eines Angebots.
Technische Unterlagen Feuerwehrschalter
Datenblätter, Zertifikate und technische Dokumentationen zu QFire BIG und LITE, Steuerboxen, Schaltboxen sowie Zubehör.
Funktionsweise + Technik QFire
Technische Grundlagen zur DC-seitigen Abschaltung, Systemaufbau, Auslösearten, galvanischer Trennung und normkonformer Umsetzung.
FAQ zum Thema Feuerwehrschalter
Antworten auf häufige Fragen zu Einsatz, Normen, Auslösekonzepten, Pflichtanforderungen und Betrieb von Feuerwehrschaltern in PV-Anlagen.
Fachbeiträge & Pressemeldungen zum Feuerwehrschalter für Photovoltaik
Der Einsatz von Feuerwehrschaltern in Photovoltaik-Anlagen wird in der Branche intensiv diskutiert – insbesondere im Hinblick auf Sicherheit, Normung und Einsatz im Brandfall. Hier finden Sie ausgewählte Fachberichte, Branchenmeldungen und technische Einordnungen.
