6 Electrical Connection SMA Solar Technology AG
36 SI80H-60H-OffGrid-IA-en-11 Installation Manual
6.5 Earthing the Battery
If you you wish to the battery, you can do so at the positive pole or at the negative pole using a
protective conductor. SMA Solar Technology AG does not recommend earthing the battery.
Conductor cross-section:
You must determine the required conductor cross-section of the PE, taking into account the applicable
local standards and directives. The calculation of the conductor cross-section of the PE depends on
the type and size of the connected battery, the external fuse in the BatFuse, and the material of the PE.
Requirement:
☐ Material of the PE conductor: copper
1. Determine the conductor cross-section for PE.
2. Earth the battery at the positive pole or negative pole.
3. Also earth the off-grid inverter:
• Strip the insulation off the protective conductor.
• Place the clamping bracket over the conductor.
Position the conductor on the left.
Example: Calculation of conductor cross-section for PE
PE is made of copper. The required conductor cross-section of PE can be calculated using the
following formula:
S
CU
I
SC
t
= Conductor cross-section in mm²
= Short-circuit current in A
= Interruption time in s
Typical tripping times for an LV/HRC fuse are around 25 ms for short-circuit currents between
2,000 A and 10,000 A. Earthing with a cross-section of 16 mm² is sufficient for short-circuit currents
up to 10,000 A.
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