SMA Solar Technology AG Electrical Connection
Technical Description SI5048-TB-TEN110340 33
6.2.1 Safety Precautions/Conditions
Connect a suitable battery to the DC side (see section 22”Technical Data” (page217)). DC must be
connected observing all local valid guidelines and regulations.
6.2.2 Cable Sizing
Be sure to observe all standards applicable to the installation site for sizing the cable.
DIN VDE 0298-4 applies in Germany.
Size the battery cables as short as possible. Long cables and insufficient cable diameters reduce
system efficiency and overload capabilities.
Example for Cable Sizing
At an AC output of 5000 W and a battery voltage of 48 V, a current of up to 140 A flows through
the battery cable.
The current flowing through the battery cable causes a power loss and a drop in voltage with every
meter of plain battery cable. You can use the following table to find the power loss and voltage drop
associated with different cable cross-sections.
This means that:
For a 10-meter distance between the Sunny Island and the battery, at least 20 m of cable are needed.
Using a cross section of 50 mm², 140 A (current flowing through the battery cable) cause a power
loss of 170 W in total and an effective voltage drop of 1.2 V.
DANGER!
Death hazard due to inappropriate handling of the battery. Death or serious
chemical burns.
• All safety and maintenance instructions provided by the battery manufacturer must
be observed.
• Use special (insulated) tools to mount and install the battery.
Cable cross-section Power loss Voltage drop
35 mm
2
12 W/m 90 mV
50 mm
2
8.5 W/m 60 mV
70 mm
2
6 W/m 45 mV
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