Solution for string combiners


Ground-mounted photovoltaic system  

Ground-mounted photovoltaic system

  • Planners and system operators face the challenge of optimizing the planned system yield and system availability.
  • Thanks to string combiner boxes from Phoenix Contact, you have the certainty of using a tested and secure solution.
  • Ease of installation and simple integration into the infrastructure of the system are further positive aspects.


According to a survey in Photon magazine, experts find 70% of German photovoltaic systems to be deficient. Assembly errors are causing the forecast yield and therefore the return on investment of a photovoltaic system to be achieved later than anticipated. The anticipated return from feed-in compensation is failing to materialize.

Discussions between employees and customers  

The correct design of the string combiner box is the crucial factor

With its functions, namely connecting, measuring, and protecting, the string combiner box (SCB) is the decisive element when it comes to a more cost effective design and long-term availability of the photovoltaic system. The SCB, however, is frequently selected solely based on cost. Quality and a long service life are a secondary consideration.

To ensure combiner boxes are safe and of a high quality, planners and installation engineers must consider standards-compliant products. Switching device standard EN 61439, which describes the design, selection of components, and the tests required, applies to the SCB. The standard also requires that the technical properties, operating conditions and correct installation and maintenance are fully documented. All information should be provided with the device in the form of installation instructions in the language of the country in which the system is installed.


Switchgear and controlgear assemblies from Phoenix Contact ensure error-free operation of photovoltaic systems. Thanks to optimally coordinated components and communication interfaces, you can connect the string combiner boxes to a higher-level park management system quickly and easily. A specialist team of experts from all the relevant divisions of the company will develop individual solutions together with you, the customer.

Preliminary development / clarification with customers  

Control cabinet solutions for every customer requirement

In the initial development phase, all our divisions work closely with customers in order to find a solution that most closely reflects their requirements. Specific challenges are identified at an early stage. This allows the development process to be handled in a target-oriented and efficient way.

Once the the initial clarification phase is complete, the design phase gets underway. During this phase, prototypes are built and undergo a specific testing procedure. The findings are used to further optimize the solution.

Testing procedures
Hotspots, for example, are detected with the aid of a temperature test. The results are used to define the optimum layout of components. This eliminates failure due to thermal overload.

The prototypes are subjected to electrical and mechanical testing in our in-house laboratories. The tests ensure that the solutions operate error-free in the intended installation environments.

Thermography testing is performed in our in-house lab to detect possible hotspots and determine the optimum arrangement of all components in the string combiner box. This means that failure due to thermal overload can be eliminated.

Thermographic images of string combiner boxes compared  

The temperature-optimized control cabinet design excludes potential failure due to thermal overloading

Following successful completion of all relevant tests in the development phase, production is given the go-ahead. The components are manufactured in a one piece flow, to ensure each individual step is efficiently implemented. This makes it possible to respond quickly and flexibly to changing designs and lot sizes. The required quality assurance information can be viewed at a glance, which ensures that the production and assembly process runs smoothly.


In the production line, tools are used that allow all items to be produced with repeat accuracy. The use of screwdrivers with torque control ensures reliable and safe connections. This ensures the consistent quality of each individual SCB. In the final production step, the final test takes place according to IEC 61439. A test report is then generated. All switchgear and controlgear assemblies as well as the components they contain have serial numbers which allow them to be uniquely identified at any time.

SCB compact and SCB next generation  

Two intelligent solution concepts: SCB with string fuse outside the control box for 32 strings and SCB with standard string fuse for 16 strings

Your advantages

  • Application-oriented analysis and consultation
  • Optimum positioning of surge protection
  • Use of the best connection technologies and suitable components
  • Reduced costs and wiring effort
  • A separate power supply unit in the field is not necessary
  • Space-saving installation, thanks to compact design
  • Application-oriented analysis and consultation


DescriptionTypeOrder No.
String combiner box for 32 strings with inline fuseSOL-SC1-32-0-FI-VMC-T1-SD1-222403683
String combiner box for 16 strings with standard string fuseSOL-SC1-16-0-F-VM-T1-SD1-112403682
DescriptionTypeOrder No.
String combiner box for 32 strings with inline fuseSOL-SC1-32-0-FI-VMC-T1-SD1-22
String combiner box for 16 strings with standard string fuseSOL-SC1-16-0-F-VM-T1-SD1-11


C6 The Exchange
Calmount Park
Dublin 12
D12 XE18