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Circuit Breakers In Solar Systems

Updated: Jun 21, 2023

A circuit breaker (also called a miniature circuit breaker, MCB or isolator) is essentially a higher evolution of the well known fuse. It provides the same protective function in an electrical system as the fuse, but unlike the fuse which often destroys itself to protect an appliance, circuit breakers are more powerful and work as switching devices by cutting-off power after which they can be reset.

They are designed to protect electrical circuits and appliances from various faults such as overloads and short circuits. When an electrical circuit or equipment experiences an overload or short circuit, the tripping device of a breaker promptly responds and disconnects the circuit, thereby preventing damage to the circuit and ensuring safety. On the other hand, when the electrical circuit or equipment is operating normally, the breaker maintains a reliable connection with the circuit through its main contact.

circuit breakers in different variations
Why Does A Solar System Need CIrcuit Breakers?

Solarkobo considers breakers as a standard requirement when designing a solar system. We consider them important to our client's investments for the following reasons:

They Protect System Components

DC circuit breakers are often installed to serve as barriers between the solar panels which provide DC and the inverter and grid power that produces AC for use in appliances. As such, they protect both the panels in any case of the AC changing direction and moving up to the panels, situation that can cause both physical and economic hazards like damage to the panels or even solar panel fires. This is their most important function.

When electrical circuits or equipment experience overloads, short-circuits, or other faults, the tripping devices of the breakers act to promptly and reliably interrupt the circuit. In normal operating conditions, the main contact of the circuit breaker establishes a dependable connection that ensures that the trip unit functions correctly without any malfunctions.

They Protect Inverters Against Lightning

At the peak of the rainy season, it is not rare to have customers complain that their inverters were damaged, sometimes beyond a quick repair, by a lightning strike.

Breakers protect the inverter against damage by lightning. Lightning bolts can reach up to 100 million volts; they generally follow the path of least resistance, meaning that they can reach and travel through the panels and into the inverters where they destroy circuit boards. Grounding or earthing provides a surefire insurance against lightning bolts but since most systems are not grounded, breakers are added to provide these protection.

They Help with Disconnecting the Panels During Maintenance or In an Emergency

Breakers make it easy for the panels to be disconnected from the system during installation or in the event of maintenance or any kind of emergency.

A Solarkobo Installation Incorporating A Breaker
A Solarkobo Installation Incorporating A Breaker
How Do They Work?

Circuit breakers commonly employ various types of magnetic and thermal trippers to safeguard the distribution system. These trippers monitor the fluctuation amplitude of the operating voltage. If the voltage drops or rises significantly above the rated voltage or if a fault occurs, the trippers promptly triggers a breaking action, preventing the circuit breaker from closing. Under stable conditions, the trippers automatically close back the circuit and reestablishes the connection.

The size of a breaker depends on the size of the system it is designed for use in. Since solar panels are often connected in strings, each string requires a breaker along its path to the charge controller.

DC circuit breakers are an essential component of solar systems hence they are standard to all our installations. They add a fraction to the price of the system they serve to protect and cannot be excused on the grounds of cost. Our university-trained engineers provide the best design and installation services for our clients in Lagos and throughout in Nigeria.

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