Cables used in a solar rooftop system

The cables used in a solar PV system transport the electricity generated from the system to the load. The cables used in the system used can be classified as Alternating Current (AC) or Direct Current (DC) cables.

The DC cables carry the power from the PV modules to inverters, whereas the AC cables carry the AC power from the inverter to the metering point.

DC Cables:

Solar DC cables interconnect solar panels to the combiner boxes to an inverter. The DC cables are usually two-core cables, a current-carrying live wire, and a negative wire, both are typically surrounded by an insulation layer. DC cables are generally made of copper conductors which provides more flexibility. As the life of the solar plant is expected to be more than 25 years, DC cables should be capable to withstand high temperatures, UV radiations, fire risk, exposure to water, etc.

There are two types of solar DC cables:

Module cables: These cables are usually integrated into the PV solar panels and are equipped with suitable to be interconnected.

fig: Module DC Cables



Main cables: The extension cables used to connect the module strings to the DC combiner boxes or the inverter.

AC Cables:

The AC cables connect the inverter to the load via protection devices. In the case of three-phase inverters, the connection to the low voltage grid is made using five-core AC cables (three live wires for the three phases that carry the current, a neutral wire carry current away from the device and ground wire (safety wire) that connects the casing of the device to the ground).

fig: AC Cables





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