Solar Combiner Box: A Beginner's Guide

Home Solar Combiner Box: A Beginner's Guide

What Is A Solar Combiner?

A solar combiner box helps bring the output of several solar strings together. This way, people can make the most of the available solar energy and use it for residential or commercial purposes. 

Each string conductor lands on the terminal of fuses, and the output of the fused inputs is brought together in a single conductor where the box is connected to the inverter. The function explained is a very basic combiner box, but when you integrate one box into the system, several features are added as per requirement.

Based on the preferences and the needs of a facility, the features are added to the box. The combiner boxes are placed between the solar inverters and modules. Hence, such boxes require little maintenance as well. Maintaining them regularly is suggested to make sure that there are no leaks. This way, loose connections will be identified before a major disruption happens. 

Common Parts & Components In A Solar Combiner

AC Combiner
Combiner Box in Beny

A solar combiner box contains the following components:

Circuit Breaker

A switch may be used to disconnect or isolate a circuit manually, or it can be used to automatically open and disconnect a circuit in the event of a short circuit or a surge in current. Circuit breakers in combiner boxes are usually single-pole, which means they only have one set of contacts for usage with a single incoming wire.


 Fuses, like circuit breakers, disconnect the appropriate circuit in the event of an over-current or short circuit emergency. The fundamental distinction between the two is that fuses are not always mechanical. They depend on a tiny wire or filament that burns through or “blows” when the fuse’s rating is exceeded. This essentially disconnects or isolates the circuit that is causing the problem. Many fuse types may be manually removed from the circuit to isolate them, then replaced as needed.


A busbar is a multi-connection point conductive metal strip or rail. This enables you to integrate numerous incoming wires into a single component. The outgoing wire is likewise connected to the busbar, ensuring that the incoming and outgoing parts are connected. The most typical use of busbars is to combine the incoming negative or ground leads from solar panels.

Bridge Bar

This is a metal strip with multiple independent “fingers” used to link or bridge the circuit breaker and fuse outgoing terminals. They’re mounted on the circuit breaker’s side opposite the entering positive wires. They combine many inputs into a single output, similar to a busbar.


The physical box in which the combiner components are installed is the enclosure.

A terminal strip

It is similar to a busbar, although it is usually constructed of ABS composite instead of metal.

Rapid Shutdown Device

The rapid shutdown device is an electric safety requirement required for solar panel systems. It helps in de-energizing a rooftop panel system quickly for best results. The requirement applies to the solar PV systems and provides a way to reduce the voltage if required of the solar modules. This device offers a safe way for the firefighters to reduce or stop the current or voltage from a PV array. 

The user enables the photovoltaic array to perform its jobs efficiently and safely. It furthermore helps avoid electrical hazards of all kinds. An inverter is already installed to shut the energy from getting past the inverter generated from modules. It cannot stop the generation of electricity. Whereas a rapid shutdown device helps stop the generation of electricity as well. 

DC Disconnect

Just as a DC disconnect helps the flow of direct current, a disconnector helps stop the flow of electricity. DC disconnects are switches that interrupt the flow of direct current. The major function of the disconnect switches is to shut the incoming flow of power from the solar panels. You can turn the switch off when you don’t need the power to flow from the solar system to the device. DC disconnects are referred to as PV disconnects as well. 

They are either installed between the inverters or the solar panels or, in most cases, built into the inverter for maximum advantages. To protect the space in case of emergencies like fire or just something else, an AC disconnect helps do that. They are installed on the exterior wall of the home or office, just beside the electric meter, for maximum advantages. 

DC Surge Protective Device

Surge protection devices are of great use, and as the name suggests, it helps protect electrical equipment in case of overvoltage. At times, lightning results in a sudden increase in the voltage, which can harm your electrical device. So to make sure that the device stays protected from all potential issues, a surge protective device is installed. Hence, you may not always know which one will be an ideal choice. 

The device is designed for transient overvoltage and surge conditions. In several incidents where large surges occur, the equipment may fail then and there. Hence to protect the device’s functioning and further disruption, protective devices are installed. At times, smaller surges may occur, and the equipment also needs to be protected. 

DC Fuse Holder

A fuse holder is a kind of fuse accessory that helps integrate fuses. You cannot drop them directly into the conductive paths because of their sizes and shapes. The fuse holder helps integrate fuses safely into the electrical circuits and helps ensure that the current flows through a full path. 

Fuse holders are hence devices that accept incoming power and assist in carrying the power through the fuse efficiently. This way, the fuses will not stay exposed and will be covered with protective layering. 

What to Look for in a Solar Combiner Box?

When purchasing a solar combiner box, keep the below factors in mind.


Your solar combiner box selection may, at times, come down to availability and price point. There are a couple of off-the-shelf solutions equipped with a wide range of potential configurations for residential installations, saving the extra expense and time related to something customized.

Now, based on the components of your system, the combiner box may have to perform more than just basic functions – combining the fuses and circuits. Not all manufacturers have the ideal off-the-shelf combiner box ready for each situation. Do you want simplicity and flexibility? Suppose you have two separate solar systems that run into the same box and will shoot out then to independent controllers. Certain boxes handle such a problem in absolutely no time, and others have to be tailored.

Before choosing a combiner, please define the inverter in use. With so many choices available, from conventional string inverters to transformer-less with MPPT, you must narrow down the code-compliant combiners.


Wireless monitoring technologies are accumulated inside the combiner box by the manufacturers. This ensures string-level and panel-level monitoring of voltage, current, and temperature. Monitoring provides real-time feedback when assigning the field, besides the inherent advantages during the installation. In this way, any mistakes or faults will be noticed early.

Solar combiner boxes need a little maintenance. The level of maintenance must be determined by the frequency of usage and the environment. It seems like a great idea to examine them for loose connections and leaks, but a correctly installed solar combiner box would last as long as your project.

When selecting the combiner box, quality is perhaps the essential factor to consider, specifically since it is the first equipment attached to the solar module’s output. Combiner boxes are quite affordable when compared to other different solar project components. Remember, a faulty box can cause an unexpected failure with smoke and flames.

The use of the whip is a new feature. It is a wire lying at the end of the solar connector. The manufacturers attach whips that enable the installer to connect output wires via a solar connection. The contractor does have to drill holes or get fittings.


Ensure that everything you select adheres to the code standards in your jurisdiction. For the roof mount, as per the rule in 2011, everyone has to install a disconnecting combiner within six feet of the array. Few codes require a rapid system shutdown.

The arc fault is the high-power electrical discharge between the conductors that release substantial heat. Insulation between the wires gets broken down due to this. The best combiner box safeguards your solar system with utmost proficiency.


Certain locations can connect everything without a combiner, based on the materials in use. The BLA or Big Lead Assembly harness, a thick gauge of wire, can handle the arcing voltage current without a combiner.

A solar combiner box is unnecessary for projects with two or three strings. Instead, it would help if you connected the string to the inverter. Combiner boxes are perfect for huge projects that have over 4000 strings. Different sized boxes are used in commercial applications to procure power from abnormal building layouts. They help the site planners to maximize power while decreasing material expenditures for utility-scale projects.

How to Mount Your Own Solar Combiner Box?

Its ease of installation and deployment usually determines an ideal combiner. It eliminates the headaches associated with a project. A box with pigtails and pre-wired fuse holders can be something that does not need installation from a licensed expert.

Eabel launched its ICS or integrated combiner solution in May. It includes pre-wiring, cable glands, touch-safe distribution blocks, and bidirectional holders for fuses. The installers will incorporate them in each project if you make it as cost-effective, simple, time-saving, and practical as a turnkey solution.

Tips to Maintain Your Solar Combiner Box

Due to humidity, ambient temperature, and dust, there are bound to be a few potential failures. The solar combiner box requires regular maintenance, or else it would not last or operate seamlessly as long. During the maintenance, the contracted parts should not be charged.

The fuse is exposed to high voltages from the inverter and battery board and must never be touched during normal operations. Before replacing and checking the fuse, please do not forget to disconnect the DC circuit breaker. Note that there are few high voltages at both ends of the circuit breaker. You must confirm that every current is zero before eliminating the fuse, the combiner box, and the solar panel.

It would help if you put on insulated gloves during the maintenance. Always remember, the insulation voltage is more than 1000V. Below are a few tips for implementing with maximum caution-

  • Cleaning the panels is easy but time-consuming. It makes sure that all the solar cells are unobstructed and get the optimum amount of insulation. Use a soft rag and biodegradable soap to get rid of dust. You can also pour water over the solar panels.
  • You do not need to cut down the trees and bushes. Please trim at least to ensure the solar panels remain without any shade.
  • Daily checks involve close monitoring of the combiner box to ensure the green light is on and that the system is working properly. Also, maintain a record of the entire system’s output. A few software will do that for you automatically.


Keep the discussion mentioned above in mind to get the perfect combiner box for your solar project. A solar combiner box that costs less than a few dollars adds sufficient value to the solar system. There are fewer cords, emergency disconnects, high security, and enhanced efficiency. Who would not wish to put one of these in their house? They provide all the amazing benefits and are simple to install. 

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