Requirements for the AC Connection


AC cable requirements as follows:

  • Conductor type: copper wire

  • External diameter: 8 mm to 21 mm

  • Conductor cross-section: 1.5 mm² to 6 mm²

  • Insulation stripping length: 12 mm

  • Sheath stripping length: 50 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).

Grounding cable requirements:

Use of fine-stranded conductors

You can use an inflexible or a flexible, fine-stranded conductor.

  1. When using a fine-stranded conductor, it has to be double crimped by a ring terminal lug. Make sure that no insulated conductor is visible when pulling or bending. This will ensure sufficient strain relief by means of the ring terminal lug.
  • Grounding cable cross-section: max. 10 mm²

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 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:

The inverter does not require an external residual-current device when operating. If local regulations require the use of a residual-current device, the following must be observed:

  • The inverter with firmware version 3.00.05.R is compatible with type A/B residual-current devices that have a rated residual current of 30 mA or higher (information about the selection of a residual-current device see technical information "Criteria for Selecting a Residual-Current Device" at 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 devices with a rated residual current of 30 mA, the rated residual current must be set in the inverter Setting the Rated Residual Current of the Residual-Current Device). In this way the inverter reduces the operational leakage currents and prevents a false triggering of the residual-current device.

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).

Grounding conductor monitoring:

The inverter is equipped with a grounding conductor monitoring device. This grounding conductor monitoring device detects when there is no grounding conductor connected and disconnects the inverter from the utility grid if this is the case. Depending on the installation site and grid configuration, it may be advisable to disable the grounding conductor monitoring. This can be necessary, for example, in a Delta IT system or other grid configurations if there is no neutral conductor present and you intend to install the inverter between two line conductors. If you are uncertain about this, contact your grid operator or SMA Solar Technology AG.

Safety in accordance with IEC 62109 when the grounding conductor monitoring is deactivated

In order to guarantee safety in accordance with IEC 62109 when the grounding conductor monitoring is deactivated, you have to connect an additional grounding conductor to the inverter.

  1. Connect an additional grounding conductor that has an cross-section of at least 10 mm Connecting Additional Grounding). This prevents touch current in the event of the grounding conductor on the AC connector bush insert failing.

Connection of an additional grounding conductor

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

  1. If an additional grounding conductor is required, connect the one that has an cross-section of at least 10 mm Connecting Additional Grounding). This prevents touch current in the event of the grounding conductor on the AC connector bush insert failing.