Appendix C - An Ac Coupled/Battery-Backup Pv System; Creating An Ac Coupled System - Magnum Energy MicroGT 500 Owner's Manual

Appendix C – An AC Coupled/Battery-Backup PV System
Appendix C – Installing an AC Coupled/Battery-
Backup PV System
AC coupling is the ability to use a battery-based inverter to continue
to power loads and charge the batteries during a utility power
outage.

Creating an AC Coupled System

In a basic PV installation, the MicroGT inverters utilize renewable
energy to offset power consumption from the utility grid. However,
they must shut down during a utility power outage. Thus, your
critical loads are no longer powered, and all the energy produced
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by your PV system during the outage is wasted.
In an AC coupled system, all the energy sources and loads are
connected directly to the AC side (Figure 12). Installing a bi-
directional battery-based inverter (i.e., Magnum's MS-PAE Series)
allows the MicroGT inverters to operate, and therefore to continue
to utilize the renewable energy from your PV system to power the
home's critical loads during the power outage—all from the AC side
Note: Refer to the instructions in the Installation section for additional
info and cautions during installation.
To install a MicroGT 500 AC Coupled PV system:
1. Complete Steps 1-6 as instructed in the Installation section in
this manual.
Note: For Step 1 (Item 2a.), the point of utility becomes the sub-
panel rather than the main panel.
2. Route and connect the appropriate wiring from the sub-panel to
the Magnum MS-PAE inverter.
3. Route and connect the appropriate wiring from the Magnum MS-
PAE inverter to the main utility panel.
Refer to Operation section in this manual before energizing your
system.
Note : The terms "Critical Loads" and Sub-panel" are used
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interchangeably.
Note : When the MS-PAE Series inverter and the MicroGT 500
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grid-tie inverter are installed in the same system, the advanced AC
Coupled Support Mode in the MS-PAE Series inverter can be enabled
so that these two inverters work together to prevent the system
battery from being overcharged. The AC Coupled Support Mode is a
control method that causes the MS-PAE inverter output frequency to
decrease, causing the output power of the MicroGT 500 to decrease in
an attempt to maintain the battery voltage around the absorb voltage.
This advanced AC Coupled Support mode is available in MS-PAE
Series inverters (≥Ver 6.0), is enabled when the battery type is set to
Custom, and activates when the battery voltage increases above the
custom-absorb voltage level.
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