Requirements for the AC Connection


Cable requirements:

  • The conductors must consist of copper.

  • External diameter: 14 mm to 25 mm

  • Conductor cross-section: 6 mm² to 16 mm²

  • Maximum conductor cross-section with bootlace ferrule: 10 mm²

  • Insulation stripping length: 12 mm

  • The cable must be dimensioned in accordance with the local and national directives for the dimensioning of cables. The requirements for the minimum wire size derive from these directives. Examples of factors influencing cable dimensioning are: nominal AC current, type of cable, routing method, cable bundling, ambient temperature and maximum desired line losses (for calculation of line losses, see the design software "Sunny Design" from software version 2.0 at www.SMA-Solar.com).

Load-break switch and cable protection:

NOTICE

Damage to the inverter due to the use of screw-type fuses as load-break switches

Screw-type fuses (e.g. DIAZED fuse or NEOZED fuse) are not load-break switches.

  1. Do not use screw-type fuses as load-break switches.
  2. Use a load-break switch or circuit breaker as a load disconnection unit (for information and design examples, see the Technical Information "Circuit Breaker" at www.SMA-Solar.com).
  • In PV systems with multiple inverters, protect each inverter with a separate three-phase circuit breaker. Make sure to observe the maximum permissible fuse protection Technical Data). This will prevent residual voltage from being present at the corresponding cable after disconnection.

  • Loads installed between the inverter and the circuit breaker must be fused separately.

Residual-current monitoring unit:

  • If an external residual-current device is required, install a residual-current device which trips at a residual current of 100 mA or higher (for details on selecting a residual-current device, see the Technical Information "Criteria for Selecting a Residual-Current Device" at www.SMA-Solar.com).

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).

Additional grounding:

Safety in accordance with IEC 62109

The inverter is not equipped with a grounding conductor monitoring device. In order to guarantee safety in accordance with IEC 62109, you must take one of the following measures:

  1. Connect a grounding conductor made of copper wire with a cross-section of at least 10 mm² to the connecting terminal plate for the AC cable.
  2. Connect additional grounding with the same cross-section as the connected grounding conductor to the connecting terminal plate for the AC cable Connecting Additional Grounding). This prevents touch current if the grounding conductor at the connecting terminal plate for the AC cable fails.

Connection of additional grounding

In some countries, additional grounding is generally required. In each case, observe the locally applicable regulations.

  1. If additional grounding is required, connect an additional grounding that has at least the same cross-section as the connected grounding conductor to the connecting terminal plate for the AC cable Connecting Additional Grounding). This prevents touch current if the grounding conductor at the connecting terminal plate for the AC cable fails.