What Is a Combiner Box?

A combiner box is used to bring together the outputs of several solar strings. The conductors of each string fall onto a fuse terminal and the outputs of the fused inputs are combined onto a single conductor that connects the box to the inverter. This is the most basic combination box, but once you have used a combination box in a solar project, there are often additional features integrated into the box. Disconnect switches, monitoring devices and remote Rapid Shutdown Devices are examples of additional equipment.

We can distribute power to the solar inverter, which saves labor and material costs by reducing wiring. Solar combiner boxes are designed to provide overcurrent and overvoltage protection to enhance the protection and reliability of the inverters

Combiner Boxes

If a project has only two or three strings, such as a typical home, a combo box is not needed. Instead, you would connect the strings directly to the inverter. Only for larger projects, anywhere from four strings to 4,000 strings, is a combiner box necessary.

However, Combiner Boxes have advantages in projects of all sizes. In residential applications, combiner boxes can bring a small number of strings to a central location for easy installation, disconnection and maintenance. In commercial applications, combiner boxes of various sizes are often used to draw power from unorthodox layouts of different building types. For utility-scale projects, combiner boxes allow site designers to maximize power and reduce material and labor costs by distributing the combined connections.

The combiner box should be located between the solar modules and the inverter. When optimally located in the array, it can limit power losses. Location is also important for price. Location is important because combiners in non-optimal locations may increase DC BOS costs due to voltage and power losses

Maintenance requirements for combiner boxes are not high; the environment and frequency of use should determine the level of maintenance. It is a good idea to check them regularly for leaks or loose connections, but if the combiner box is installed correctly, it should continue to function for the life of the solar project

The quality of the combiner box is the most important consideration when selecting a combiner box, especially since it is the first piece of equipment connected to the solar module output. Compared to other equipment in a solar project, combiner boxes are not expensive, but a faulty combiner box can fail in a dramatic way

This year, arc fault protection and remote quick shutdown devices are more popular than ever, due to recent changes in the National Electrical Code that require their use in many solar applications. New technologies and components are driven by changes in the NEC and the desire to improve energy efficiency and reduce labor costs. Some of these new components include: higher voltage components, integral mounting hardware and custom grounding options.

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