Tips For Evaluating And Specifying A Solar Combiner Box

The output that is provided by a number of solar strings can be combined through the use of a solar combiner box. Each of the solar strings and their conductors is connected to the fuse terminal. The output of all these inputs subsequently flows through the combiner box’s single conductor, which is connected to the inverter. While this is the basic functioning and concept of a solar combiner box, they may include many other features as well. For instance, a modern combiner box may have features including the remote and rapid shutdown, monitoring, disconnection of particular switches and others.


The solar combiner box not only consolidates the outgoing power, it may also consolidate the incoming power so that it attains the form of one main and single field which distributes itself subsequently to the entire solar inverter. The combiner box also provides protection against greater voltage and current levels and has utmost reliability.

How to evaluate or specify a solar string combiner box

The combiner boxes may be used in the large commercial and utility power plants and may also be home to the other electrical components including the protective devices, DC disconnect, monitoring hardware, and other components. When you want to evaluate or specify a combiner box, here are some aspects to consider.


The new combiner boxes have the enclosures having an outdoor rating. They may be rated as NEMA 4, 4X, or 3R. Enclosures with the rating of 4 are quite popular today and are made of steel, while the 4 X rating enclosure if of a non-metallic build. A breather or vent can be added to the enclosure in areas where humidity may cause a problem. The enclosure of the box is often its most expensive component. You also need to consider the color, size, mounting position and other aspects of the enclosure.

Color of the combiner box

The light color solar combiner box absorbs lesser heat while the dark shades combine more heat. Hence the color of the combiner box should also be considered if you want a safe and reliable functioning.

Mountain area

If the combiner box has been mounted directly exposed to the sunlight, high amount of heating may occur. If the temperature keeps rising, the internal components of the box may undergo wear, may get damaged, and their reliability will also decrease. Hence it is recommended that the combiner box is mounted on a wall that faces north, and the area is shaded.


The larger the size of the combiner box, the more ventilation, and space it would provide for storing and placement of the internal parts and components. The large combiner boxes get more air and can offer greater life to the entire internal components. The large boxes also offer more room for maintenance and service purposes, and also make wiring and installation easier.

Third-party certification

Only a high-quality combiner box can be used for long-term and with complete peace of mind. The combiner box may catch flames, emit smoke and maybe more prone to accidents if it is of low quality and faces a hazard. Hence you should look for the third-party certifications to ensure that the box can withstand the hazards. The certification standard that is relevant here is the UL1741  standard.

Whip incorporation

The new combiner boxes have a whip or a small length of output electrical wire that has on its end a solar connector. Now the contractors are not required to drill holes for installation and usage purposes. The small wire is handy and provides for the instant transfer of power, as it can be easily connected to the mating/ another solar connector. The process is as simple as plugging and requires least of time and efforts.

Lastly, you can also opt for the output terminals that do not have bends. If there are bends, there will be greater stress on the components that have been placed in the box and the installation time will also increase. You can evaluate your combiner box on the basis of all the aspects given below and choose one that suits your setting the best way.


What do you think?


Written by Mike

Content AuthorYears Of Membership


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