Requirements for the AC Connection

AC cable requirements:

  • Aluminum or copper cables must be used.

  • The conductors must be solid, stranded or fine-stranded. When using fine-stranded wire, bootlace ferrules must be used.

  • The maximum permitted temperature for the terminal block of the AC connection of 90°C must be observed.

  • Cable cross-section L1, L2, L3: 50 mm² to 150 mm² (300 kcmil to 1 AWG)

  • Cable cross-section grounding conductor when using copper cable: 10 mm² to 50 mm² (1/0 AWG to 6 AWG)

  • Cable cross section grounding conductor when using aluminium cable: 25 mm² to 50 mm² (1/0 AWG to 4 AWG)

  • Maximum permissible temperature: 90°C

Residual-current monitoring unit (RCMU):

The inverter is equipped with an all-pole sensitive residual-current monitoring unit in accordance with IEC/EN 62109-2 and VDE 0126-1-1. The all-pole sensitive residual-current monitoring unit monitors AC and DC residual currents. It disconnects the inverter redundantly from the utility grid in the event of residual current jumps of > 30 mA. If the residual current monitoring unit malfunctions, the inverter is immediately disconnected from the utility grid at all poles. If the protection by automatic disconnection of the power supply according to DIN VDE 0100-410 is fulfilled by an appropriate overcurrent protective device, the inverter does not require an external residual-current device for safe operation. If local regulations require the use of a residual-current device, the following must be observed:

  • The inverter is compatible with type B residual-current devices. For SHP 125-US-20 the rated residual current must be 1250 mA and for SHP 150-US-20 the rated residual current must be 1500 mA or higher (for information on selecting a residual-current device, see Technical Information "Criteria for Selecting a Residual-Current Device" under www.SMA-Solar.com). Each inverter in the system must be connected to the utility grid via a separate residual-current device.

  • When using residual-current device with a lower rated residual current, there is a risk of false tripping of the residual-current device, depending on the system design.

Overvoltage category:

The inverter can be used in grids of overvoltage category III or lower in accordance with IEC 60664-1. That means that the inverter can be permanently connected to the grid-connection point of a building. In case of installations with long outdoor cabling routes, additional measures to reduce overvoltage category IV to overvoltage category III are required (see the Technical Information "Overvoltage Protection" at www.SMA-Solar.com).

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