What is a Photovoltaic Combiner Box?

A photovoltaic (PV) combiner box is a crucial component in solar panel systems. It aggregates the output of multiple solar panels, enabling a streamlined connection to the inverter. This box plays a key role in consolidating the energy collected, providing protection, and ensuring the efficient operation of the solar power system.

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Technical Requirements of a Combiner Box

The combiner box must be robust, with a structure typically made from cold-rolled steel plate (minimum Q235) with a thickness of at least 1.5mm. It should be sealed, dustproof, moisture-resistant, and have sufficient mechanical strength to withstand dynamic and thermal stresses. The protection level of the outer shell should meet at least IP65 standards, and for cable entries, IP68 rated cable glands are preferred.

Performance Parameters

All internal electrical circuits should withstand at least DC1000V. The main circuit should use copper busbars capable of handling ≥250A. The insulation resistance between each circuit and exposed conductive parts should be no less than 1000Ω/V of the nominal voltage. Additionally, the combiner box should feature current monitoring for each input line and have an RS485 interface for data communication.

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Installation and Connection of PV Combiner Boxes

The combiner box should be installed vertically, preferably on PV support structures. For external connections, the input, output, communication, and grounding terminals are located at the bottom of the casing. Positive connections from PV modules should be on the left bottom side, while negative connections on the right.

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Electrical Installation Precautions

Only qualified electrical engineers should handle the installation and wiring, complying with national and local standards. Before installation, an insulation test should be conducted using a megohmmeter. Ensure that the internal arrangement of components meets safety and maintenance requirements.

Electrical Wiring and Steps

Careful attention should be given to polarity in input and output connections. Secure external wiring connections and ensure that the cabling is neat and fire-resistant. The grounding of the combiner box should be securely connected, and communication wiring should use IP68 rated cable glands.

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Proper installation and maintenance of the PV combiner box are vital for the efficient and safe operation of a solar power system. By adhering to the technical requirements and installation guidelines, the longevity and performance of the solar system can be significantly enhanced, contributing to a more sustainable and reliable energy solution.