In photovoltaic (PV) power systems, the combiner box plays an essential role. It consolidates and distributes the direct current (DC) generated by multiple PV panels, facilitating the connection to inverters or other devices. Let’s explore the differences between DC combiner boxes and AC combiner boxes.

Combiner Box

DC Combiner BoxWorking Principle: The primary task of a DC combiner box is to consolidate and distribute the DC electricity produced by PV panels. When PV panels generate DC electricity, they are connected to the input ports of the combiner box via cables. The internal circuitry of the combiner box then consolidates and distributes this DC electricity, outputting the aggregated DC to inverters or other devices. During the consolidation process, the combiner box monitors parameters such as current, voltage, and power for each PV string and implements protection mechanisms like short-circuit protection, reverse-polarity protection, and over-current protection through protective devices.

Main Functions:

  • Consolidation Function: Connects multiple PV panels in series to form a larger voltage output, increasing the system’s voltage level, reducing current loss, and thereby enhancing system efficiency.
  • Monitoring Function: Continuously monitors parameters like current, voltage, and power for each PV string to ensure the system operates smoothly.
  • Lightning Protection: Often equipped with lightning protection devices to effectively prevent damage from lightning strikes to the PV power system, ensuring system safety.

AC Combiner BoxRole: The AC combiner box is a crucial component that serially connects the output of inverters with the input of AC distribution panels or step-up transformers. It aggregates the AC output from multiple inverters before outputting it, simplifying the connection between series inverters and AC distribution panels or step-up transformers.

Main Functions:

  • Consolidation Function: Aggregates the AC output from multiple inverters for output.
  • Protection Function: Protects inverters from harm from the AC grid side/load, serving as a disconnect point for inverter outputs, enhancing system safety.
  • Monitoring Function: Real-time monitoring of AC current, voltage, and other parameters.

In summary, DC combiner boxes primarily handle DC electricity, while AC combiner boxes deal with AC electricity output by inverters. The choice between using a DC or AC combiner box depends on the structure and requirements of the PV power station system.