SMA STP 50-40 - Connecting the Inverter to the Utility Grid

6 Electrical Connection
SMA Solar Technology AG
Operating manualSTP50-4x-BE-en-2338
☐ 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 (see Section13,
page120). 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 is compatible with type B residual-current devices that have a rated residual
current of 300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 < 500mA, the rated residual
current must be set in the inverter (see Section8.23, page83). In this way the inverter
reduces the operational leakage currents and prevents a false triggering of the residual-current
device.
Overvoltage category:
The product can be used in grids of overvoltage categoryIII or lower in accordance with
IEC60664-1. That means that the product 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).
6.2.2 Connecting the Inverter to the Utility Grid
Requirements:
☐ The connection requirements of the grid operator must be met.
☐ The grid voltage must be within the permissible range. The exact operating range of the
inverter is specified in the operating parameters.
Procedure:
1. Disconnect the miniature circuit breaker from all 3 line conductors and secure against
reconnection.
2. Ensure that the DC load-break switch is in the O position and is secured against reconnection.