Photovoltaic PV solar combiner box

What is a solar combiner box

The solar combiner box is a wiring device in the photovoltaic power generation system that ensures the orderly connection and convergence function of photovoltaic modules. This device can ensure that the photovoltaic system is easy to cut off the circuit during maintenance and inspection, and reduce the range of power outage in case of photovoltaic system failure.

A combiner box refers to a system where users can connect a certain number of photovoltaic cells with the same specifications in series to form a series of photovoltaic cells. Then, several photovoltaic series are connected in parallel to the photovoltaic combiner box. After converging in the photovoltaic combiner box, a controller, DC distribution cabinet, photovoltaic inverter, and AC distribution cabinet are used together to form a complete photovoltaic power generation system, achieving grid connection with the mains.

Composition of combiner box

1. Box body

The box body is generally made of materials such as steel plate spray coating, stainless steel, engineering plastics, etc. It has a beautiful and generous appearance, is sturdy and durable, is easy to install, and has a protection level of IP54 or above. It is waterproof and dustproof, and meets the requirements of long-term outdoor use.

2. DC circuit breaker

DC circuit breaker is the output control device of the entire combiner box, mainly used for the opening/closing of the line. Its working voltage is as high as DC1000 V. Due to the fact that the energy generated by solar modules is direct current, it is easy to generate arcing when the circuit is disconnected. Therefore, when selecting, it is necessary to fully consider its temperature and altitude reduction factor, and it is necessary to choose a photovoltaic specific DC circuit breaker.

3. dc fuse 

When the component experiences reverse current, the photovoltaic dedicated DC fuse can timely cut off the faulty string, with a rated working voltage of DC1000 V and a rated current of generally 15 A (for crystalline silicon modules). The DC fuse used in photovoltaic modules is a specialized fuse designed specifically for photovoltaic systems (with an external size of 10mm x 38mm), installed on a dedicated enclosed base to prevent current backflow between strings and burning the modules. When current backflow occurs, the DC fuse quickly exits the faulty string from the system operation without affecting other normal working strings, which can safely protect the photovoltaic string and its conductors from the threat of reverse overload current.

4. DC surge protector

As the photovoltaic combiner box is installed in an outdoor environment, we must consider lightning protection for the combiner box. For this purpose, we have connected a photovoltaic DC specific lightning surge protector (i.e. lightning arrester) in parallel at the DC output part of the combiner box. Once a lightning strike occurs, the surge protector will quickly discharge excessive electrical energy, ensuring stable output of electrical energy and protecting the combiner box from lightning damage. The installation of lightning protection components in a junction box is called a photovoltaic lightning protection junction box.