SMA Solar Technology AG
6 Electrical Connection
Installation Manual
STP5-9TL-IA-en-10
35
6.3 AC Connection
6.3.1 Conditions for the AC Connection
Cable requirements:
☐ External diameter of the cable must correspond to the clamping range of the cable gland:
12 mm ... 21 mm
☐ Recommended conductor cross-section for stiff or flexible cables, with or without bootlace
ferrule: 1.5 mm² ... 6 mm²
☐ Conductor cross-section: 10 mm² at maximum
☐ Stripping length: 15 mm
☐ The cable must be dimensioned in accordance with the local and national directives for the
dimensioning of cables. The requirements for the minimum conductor cross-section derive from
these directives. Influencing factors for cable dimensioning are, among others, the following:
nominal AC current, type of cable, routing method, cable bundling, ambient temperature and
maximum desired line losses (for calculation of line losses, see design software "Sunny Design"
with software version 2.0 or higher at www.SMA-Solar.com).
Switch-disconnector and cable protection:
• In plants with multiple inverters, protect every inverter with a separate three-phase miniature
circuit-breaker. Observe the maximum permissible fuse protection (see Section 13 "Technical
Data", page 90). That prevents residual voltage being present at the corresponding cable after
disconnection.
• Loads installed between the inverter and the miniature circuit-breaker must be protected
separately.
Residual-current monitoring unit:
• If an external residual-current device is prescribed, install a residual-current device that trips at
a residual current of 100 mA or higher (for information on the selection of residual-current
devices, see the Technical Information "Criteria for Selecting a Residual-Current Device" at
www.SMA-Solar.com).
Damage to the inverter by using screw-type fuses as switch-disconnectors
Screw-type fuses (e.g. DIAZED fuses or NEOZED fuses) are not switch-disconnectors.
• Do not use screw-type fuses as switch-disconnectors.
• Use a switch-disconnector or miniature circuit-breaker as a load disconnection unit
(for information and examples for designing, see the Technical Information
"Miniature Circuit-breaker" at www.SMA-Solar.com).
