DC Circuit Breaker for Solar System: All You Need to Know

Home DC Circuit Breaker for Solar System: All You Need to Know

DC circuit breakers are essential components of the solar system. It acts as a barrier between Direct Current and Alternating Current. Installation and routine maintenance require a barrier between the panels and the alternating current. DC circuit breakers are essential for electric protection. 

DC circuit breakers are crucial because they can function even when the alternating current unit has completely failed. Their usage can result in less requirement of maintenance, better reliability, and a lesser failure rate. 

Therefore, this blog will attempt to explain why DC Circuit breakers are crucial for solar systems. DC circuit breakers are essential to ensure that the quality of the photovoltaic panel stays for a longer period.

AC Circuit Breaker vs. DC Circuit Breaker

AC Circuit breaker and DC Circuit breaker work for different types of electric currents. They have their own vital roles to play with respect to the type of the current they are dealing with. 

Direct Current produces an output where the voltage is constant. On the other hand, alternating current produces a current which is rather unstable. It can vary from positive to a negative voltage, and in most cases, the cycle stays from 50-60 hertz. 

The usual electric grids work with AC power, whereas the more intensive workplaces use DC current to supply their power.

The extinguishing point for the DC circuit breaker is high. The voltage is continuous and is more resistant to any obstacle. AC circuit breakers are more common than DC circuit breakers. This most likely happens because DC circuit breakers are still the newer part of technology that people are getting used to in their domestic lives. 

DC circuit breakers are not only protective devices for photovoltaic solar panels, but they are crucial for electric vehicles, LED lamps, and more. These units require DC circuit breakers to ensure proper functioning. 

DC circuit breakers have been an important part of industries that require heavy inputs. Examples can be machinery which can require plenty of energy and precision. Arc Welding also requires input that can be given by DC circuit breakers.

In the case of heavy-duty batteries, solar power installations, heavy machinery, DC current is the ideal type that can provide them the required input. AC current is ideal for powering high-power motor drives, and transmission of power over a long distance. 

DC current is excellent for charging stations for electric vehicles, electric motors which require direct current, powering fuse boxes in both electric and gas cars, and much more. Therefore, AC and DC Circuit breakers have their own roles to play, and none can be called better than the other.

DC Circuit Breaker in PV System

Photovoltaic systems can be a very powerful mechanism for renewable energy. It can consist of one or more solar panels. Further, they are combined by an inverter and other electrical and mechanical hardware. However, the same systems require to be protected and maintained at all costs. The most minor incident in any of the functions can turn out to be a massive problem for the entire system. 

Therefore, DC circuit breakers are one of the most essential components required by the PV system. The entire process of its function, wiring, and its safety tips would be thoroughly discussed below. Let’s take a look at the various aspects of a DC circuit breaker.

How Does It Work?

Image of DC circuit breaker
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The essential question arises, how do DC Circuit breakers actually work?  As similar to AC circuit breakers, DC circuit breakers also work with the method of thermal and magnetic protection.

In the case of thermal protection, it trips the breaker when the electric current is beyond the rated value. As more heat is generated, the bimetallic contact heats up and expands. The thermal protection can help in cases of current that have been overloaded. 

In the case of magnetic protection present in the DC circuit breakers, it trips the DC circuit breaker when fault current is present in a massive amount. DC circuit breakers have the capacity to break fault current even at its highest stage. Magnetic protection in DC circuit breakers is important because they can stop short circuits and other faults.

With particular response to systems that have Solar PV panels in them, DC circuit breakers are crucial. Solar panels circuits are an expensive part of the system. Therefore, it is important to protect them through the means of the DC circuit breaker.  All the circuits of the Solar PV panels are connected to a combiner box. Additionally, the DC circuit breaker protects the circuits and the panels.

The solar irradiation received by photovoltaic solar panels can be converted into direct current. DC circuit breakers are essential for photovoltaic installation. Even a small mismatch can cost a fortune. In the case of electric vehicles, their batteries are charged with the help of EV charging stations. The system here works in alignment with direct current. Therefore, it is essential to have DC circuit breakers in these systems to avoid any mishaps. 

Photovoltaic solar panels and electric vehicles can work well together because they primarily deal with direct current. Further, the conversion of this direct current to alternating current is not mandatory. DC circuit breakers make it easy to control automatic systems. That takes place so they can provide a response that is quick.

Wiring tips

Image of wiring
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The DC circuit breaker’s wiring is simpler than the one present in AC circuit breakers. While AC circuit breakers can take up to three live conductors, which can be different, DC circuit breakers can take up to one. 

The physical installation of a DC circuit breaker can be similar to the AC circuit breakers. DC circuit breakers have a particular design constructed for them, in the fuse boxes. Through the means of these, they can protect inverters, solar PV, and more. 

In terms of DC circuit breakers, they are easier to install because there is no risk of putting the wires in the wrong connection. There is just one live conductor present, and everything else follows through. 

The electric wiring which is joining the DC circuit breaker and the device should be shielded and be provided with sufficient current. Even a cable that is not the correct size can result in malfunction. The circuit can be directly connected to the device which is powered by the current.  It would require a switch for control. It can also use a plug-in outlet for control purposes.

Solar PV panels may have one or more installations as per their capacity. The circuits which are connected to a PV combiner box must be protected by a DC circuit breaker. With all the power combined through the solar panels, they can be used with a current output that is single directed. If there are many panels for DC loads, then a number of DC circuits breakers would need to be installed.

Safety tips

Image of individual welding
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In cases of transformerless inverters, an ungrounded array is required to provide input to the transformers. This would additionally require a DC isolator which is double poled. 

In the case of models which can carry both DC and AC isolators, the switch should be able to handle 20% voltage in the open circuit array. In the case of a short circuit array, the voltage should be above 25%.

As mentioned above, DC circuit breakers carry an extinguishing point to them. It is essential to include extra arc extinguishing measures because they have the capacity to face interruptions better. If a system uses a battery bank, it should be shielded by a DC circuit breaker. In the case of an inverter that is converting direct current to alternating current, it would require a DC circuit breaker as well, for safety. 

An electric panel consisting of DC loads would require DC circuit breakers. During maintenance,  installation, or any kind of emergency, it is vital to separate the AC side from the panel side. In such cases, the DC isolator’s switches become an important part.

Homeowners who have solar panels can have direct current applications in their houses. In these cases, it is essential to have DC circuit breakers for shielding. There are many solutions that need to be designed. They must also install separate fuse boxes with many circuit breakers for both direct and alternating current.DC circuit breakers can operate the flow of current in a  particular direction. 

Therefore, an attempt or an accident that has tried to change the direction would result in safety concerns and damage to the solar cells. In the case of LED lamps, they can function with the help of a diode which is light-emitting. However, this function can only take place where there is a direct current present. 

Although LED lamps are efficient in terms of energy saving, they are still expensive to invest in. Therefore, protection of the LED lamp is essential. A DC circuit breaker will be required to provide protection to the direct current that is being used to connect circuits for the functioning of the LED lamp. Users should also know whether there has been an internal system that may require an alternating current circuit. In that case, the individual concerned should buy as per the internal system of the LED lamp.

In the case of industries that rely on welding, DC circuit breakers are essential to promise safety in the operation and stop any damage to the machine. In cases of other industrial machines, transport devices, and more, the power circuit and the control circuit would be separated from each other. This happens because they function at different levels of voltage. Furthermore, this voltage would be protected by the DC circuit breaker. The circuit breaker and the electric supply should be the same. Any difference between these can result in accidents.

What to Consider When Choosing DC Circuit Breakers for Solar Panels?

Workers establishing panels
Source: Unsplash

There are some factors that need to be considered when choosing DC circuit breakers for solar panels. Following is the list of the essential factors:

  • The Number of Strings Present in the Isolator

If there are two poles present, then there should be a single string. When it comes to two poles, there should be two strings. For Isolators that carry external Direct Current, you can opt for multiple string panels. For in-built DC Isolators, a single maximum power point tracker that can act as a converter would work with a common string inverter. 

  • Installations and Their Effect on the Environment

DC isolators can normally function in temperatures that can consist of -40 degrees Celcius to 60 degrees celsius. The temperature is an essential factor to check during the installation process because they are relied upon to understand the protection and fireproof systems. The enclosure box should be able to control fire ratings from UL94V-0 to UL 94V-2.

  • Size of the Voltage in the System

Isolators carrying operational voltage should be greater, or equal to the one that the system requires. The most common requirements include 1500V, UL508i 600V, IEC60947-3 1000V. Single-phase inverters that are connected to system voltage can usually work with 600V. In terms of three-phase string inverters, the system voltage can reach up to 1000V and 1500V. The same would apply to inverters that are centralized.

  • Current Rating, and the Voltage of String Panels

Maximum voltage and the current that the panel string can carry are important factors to decide which DC isolator should be selected. PV inverter parameters and inverter manufacturers can work well in that order to save cost. For this, the user needs to understand how the concept works, and what they need to do to save the cost. The size can be designed as per the voltage of the Direct Current inputs. 

The curve of current can be used to help to balance the situation that can arise in different weather and temperature conditions. It is essential to understand the maximum voltage and current that the PV string can bring in its isolated stage.

Most importantly, these factors and instruments should be managed properly to ensure that there is no safety hazard.


DC circuit breakers are an essential component of PV systems. Without their protection, photovoltaic panels can become more prone to damages and system failure. Alternating current breakers and DC circuit breakers have their own roles to play in the system. Therefore they both are important for proper functioning. If the proper wiring tips, safety measures, maintenance, and procedure are followed, DC circuit breakers can act as the prominent shield that is required by plenty of systems such as photovoltaic panels.

To find the best protection for photovoltaic systems, and the functioning of DC circuit breakers, you can visit BENY’s site. It can provide you with all the essential products, and the information you need.

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