10
3.4 SLD - AC Coupled PV System with Back-up Power Operation
The single line diagram shown below is a representation of a typical installation configured for utility interactive and
back-up power operation, with AC coupled PV connected to a critical load panel. This drawing is a guideline only,
and is not a substitute for a code compliant installation. All components required for a code compliant installation
are the responsibility of the licensed installer, including any additional circuit protection requirements not shown
here.
NOTES
1.
The backup power bus must be electrically isolated from the main electrical bus. Do not tap the neutral wires of the main
and backup buses. A separate line, neutral, and ground must be run to each of the load and grid ports of the battery
system. Refer to the installation manual for wiring details.
2.
Energy meter supports 1Ø and 3Ø configuration. In the above case, the energy meter was removed from the PCS cabinet
and relocated to the main panel.
3.
3Ø service shown. For 1Ø service, do not populate L2, L3 ph components.
4.
The battery system must be earth bonded to the building ground to meet lightning protection requirements.
5.
The battery system load and grid ports are independently controlled circuits. Should the electrical code require additional
“line-of-sight” disconnects, a separate disconnect must be used for each of the grid and load ports. The disconnects
and/or circuit breakers must operate independently of each other, and not be ganged.
6.
The PCS provides galvanic separation of AC and DC sources. Overcurrent protection devices, RCD Type A (300 mA), are
sufficient for protection of both AC Grid and AC load ports.
7.
Total AC nameplate of PV not to exceed 5 kW. String inverter shown for simplicity. Multiple AC strings of micro-inverters
permitted. Any additional PV installed on the grid side of the battery system operates independently from the battery
system, and is only limited by the interconnection requirements of the utility service provider.
8.
The maximum conductor size permitted for the PCS grid port is 16 mm
2
, and maximum breaker rating of 63 Amp to
protect the internal circuits of the PCS. The ESS breaker rating and conductor size can be reduced, however, these
parameters are subject to the total possible continuous output current of combined PV and ESS generation at the ESS grid
breaker in the main electrical panel. Variables that determine conductor sizing include; PV continuous output current
rating connected to the ESS load terminal, total self-supply current to the main electrical panel (load connected PV plus
ESS output), and length of run from the ESS grid port to the main electrical panel (voltage drop). Conductor sizing is the
responsibility of the installer as per the actual installation, compliant to local / national electrical codes. Refer to the
technical data in section 17.1 for Maximum AC fault current and duration (short circuit).
9.
The PCS short circuit withstand capacity is rated at 10 kA (1 second). Circuit protection must not exceed this rating.
*DRED: Australia only.
** See note 8.
** See note 9.
N L3 L2 L1
Main Bus
3
M
Emergency switching device
Figure 6: Single Line Diagram: Typical AC coupled PV system.
