Connecting the Battery Fuse to the Sunny Island
Qualified person
Selecting the battery fuse
The battery fuse protects the DC cables and the battery against a short circuit. The battery fuse must be designed according to the maximum short-circuit current of the battery, the conductor cross section of the DC cables and the technical data of the Sunny Island ( > DC Connection for Battery). The locally applicable standards and directives must be complied with.
If a battery fuse is already available, no further fuse is necessary.
Tip: Install a battery fuse of the type enwitec BAT FUSE HERITAGE 01 or enwitec BAT FUSE HERITAGE 03.
Maximum cable length for the DC connection
Long cables and insufficient conductor cross-sections reduce the efficiency of the system and the overload capacity of the inverter.
- The length of all DC cables from the battery via the battery fuse to the Sunny Island must be smaller than 10 m.
Connection of DC loads or DC energy sources
The DC connection of the inverter is primarily intended for connecting a battery. When DC loads or DC energy sources are connected, electromagnetic interference may temporarily interfere with operation. Therefore, DC loads or DC energy sources that are immune to electromagnetic interference should be used. This is the case if DC loads and DC energy sources have interference immunity for industrial environments (e.g. according to EN 61000-6-2).
SMA recommends the Sunny Island Charger of MSTE SOLAR GmbH as DC charge controller.
The recommended minimum conductor cross-section depends on the battery voltage, the power and the length of the cable:
Cable requirements when using the inverter with an enwitec BAT FUSE HERITAGE 01 or enwitec BAT FUSE HERITAGE 03 battery fuse:
Sunny Island | Cable length1) | Conductor cross-section | Cable diameter | Terminal lug |
|---|---|---|---|---|
SI8.0H | ≤ 5 m | 70 mm² | 14 mm to 25 mm | M8, 20 mm to 25 mm wide |
> 5 m | 95 mm² | 14 mm to 25 mm | M8, 20 mm to 25 mm wide | |
SI6.0H | ≤ 5 m | 50 mm² | 14 mm to 25 mm | M8, 20 mm to 25 mm wide |
> 5 m | 70 mm² | 14 mm to 25 mm | M8, 20 mm to 25 mm wide | |
SI4.4M | ≤ 5 m | 50 mm² | 14 mm to 25 mm | M8, 20 mm to 25 mm wide |
> 5 m | 70 mm² | 14 mm to 25 mm | M8, 20 mm to 25 mm wide |
1) Cable length from the battery to the Sunny Island via the fuse switch-disconnector
WARNING
Danger to life due to incompatible lithium-ion battery
An incompatible lithium-ion battery can lead to a fire or an explosion. With incompatible lithium-ion batteries, it is not ensured that battery management is intrinsically safe and will protect the battery.
- Ensure that the lithium-ion batteries are approved for use with the Sunny Island (see technical information “List of Approved Batteries” at www.SMA-Solar.com).
- If no lithium-ion batteries approved for the inverter can be used, lead-acid batteries can be used.
- Verify that the battery complies with locally applicable standards and directives and is intrinsically safe.
Procedure:
- Ensure that the load-break switch of the battery fuse is open and secured against reconnection.
- On the Sunny Island, remove all screws of the lower enclosure lid using an Allen key (AF 5) and remove the enclosure lid. Retain the screws and conical spring washers for later use.
- Connect the DC power cable of the battery fuse with the correct polarity ( > Connecting the DC Power Cable).