What is an inverter AC

Requirements for the AC connection


AC cable requirements:

  • Conductor type: copper wire

  • Outside diameter: 18 mm

  • Conductor cross-section: 4 mm² to 16 mm²

  • Stripping length: 18 mm

  • Stripping length: 250 mm

  • The cable must be designed according to the local and national guidelines for the dimensioning of lines, from which requirements for the minimum conductor cross-section can result. Influencing factors for cable dimensioning are e.g. B. the nominal AC current, the type of cable, the type of installation, the accumulation, the ambient temperature and the maximum desired line losses (for calculation of the line losses, see the "Sunny Design" design software from software version 2.0 at www.SMA-Solar.com).

Switch disconnectors and line protection:

Damage to the inverter due to the use of screw fuses as a load disconnection device

Screw fuses (e.g. DIAZED fuse or NEOZED fuse) are not switch disconnectors.

  1. Do not use screw fuses as a load disconnection device.
  2. Use a switch disconnector or miniature circuit-breaker as a load-break device (for information and layout examples, see Technical Information "Miniature Circuit Breakers" at www.SMA-Solar.com).
  • In systems with several inverters, each inverter must be protected with its own miniature circuit breaker. The maximum permissible protection must be observed (Technical specifications). This will prevent residual voltage from being applied to the cable in question after it has been disconnected.

  • Loads that are installed between the inverter and the line circuit breaker must be protected separately.

Residual current monitoring unit:

The inverter does not require an external residual current circuit breaker for operation. If the local regulations require a residual current circuit breaker, the following must be observed:

  • The inverter is compatible with residual current circuit breakers of type A and B, which have a rated residual current of 100 mA or higher (for information on selecting a residual current circuit breaker, 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 public grid via its own residual current circuit breaker.

Overvoltage category:

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

Protective conductor monitoring:

The inverter is equipped with protective conductor monitoring. The protective conductor monitoring detects when no protective conductor is connected and in this case disconnects the inverter from the utility grid. Depending on the installation location and network configuration, it can be useful to deactivate the protective conductor monitoring. This can e.g. This may be necessary, for example, in a Delta IT network or other network forms, if there is no neutral conductor and you want to install the inverter between 2 phases. If you have any questions about this, contact your grid operator or SMA Solar Technology AG.