3. Screw the clamping bracket tight using the
M6x16 cylindrical screw and the conical spring
washer M6 (torque: 6 Nm). The teeth of the
conical spring washer must face the clamping
bracket.
6.4
DC Connection
6.4.1
Requirements for the DC Connection
Requirements for the PV modules per input:
☐ All PV modules must be of the same type.
☐ All PV modules must be aligned and tilted identically.
☐ On the coldest day based on statistical records, the open-circuit voltage of the PV array must
never exceed the maximum input voltage of the inverter.
☐ The same number of series-connected PV modules must be connected to each string.
☐ The maximum input current per string must be maintained and must not exceed the through-
fault current of the DC connectors (see Section 10 "Technical Data", page 41).
☐ The thresholds for the input voltage and the input current of the inverter must be adhered to
(see Section 10 "Technical Data", page 41).
☐ The positive connection cables of the PV modules must be fitted with the positive DC
connectors (for information on assembling DC connectors, see the DC connector installation
manual).
☐ The negative connection cables of the PV modules must be fitted with the negative DC
connectors (for information on assembling DC connectors, see the DC connector installation
manual).
Use of Y adapters for parallel connection of strings
The Y adapters must not be used to interrupt the DC circuit.
• Do not use the Y adapters in the immediate vicinity of the inverter. The adapters must not
be visible or freely accessible.
• In order to interrupt the DC circuit, always disconnect the inverter as described in this
document (see Section 9, page 38).
6 Electrical Connection
SMA Solar Technology AG
Operating Manual
STP20-25TL-BE-en-11
28