AC Coupled Inverter Charger

Sigineer Power’s AC coupled inverter is off-grid, it can keep your grid-tie PV system working at blackouts.

Most grid-tie system are useless when the grid fails. They shut down at the very moment that the power is most needed. This does not need to be the case. One way to ensure that a PV array does not become stranded during utility outages is to make it into an AC COUPLED backup power system.

AC Coupled BackUp Power Systems utilize an Ac coupled inverter (battery-based inverter/charger) to “fool” the grid-tie inverter to “think” that it’s still connected to the utility by offering it with a pure sine wave AC signal.

After the GT inverter “qualifies” the AC signal, it starts producing AC power which is sent to the AC output of the battery-based inverter/charger. The two sources of power are combined and synchronized in phase to power loads and the excessive PV production is used recharge the batteries.

Sigineer’s battery-based AC coupled inverter chargers have below benefits:

1 Help solar installers to easily retrofit an existing grid-tie solar system into a battery backup off-grid system without rewiring the solar arrays or adding other components.
There is no need to be concerned about cable loss in long, expensive low voltage cable runs in comparison to the DC-coupled systems.
2 Increase the overall inverter capacity by paralleling AC coupled inverter with the grid-tie inverter.
So if you have a 5 kW solar inverter and a 15 kW battery inverter, your total output would be 20 kW.
The modification is simple and straightforward: connect the AC output of the grid-tie inverter to our inverter charger AC output(NOT AC input terminal which is dedicated for shore power), and connect the grid power to our inverter AC input.

The Sigineer Power AC coupled inverter works in two modes:

1 DC to AC Battery mode
The inverter’s pure sine wave AC output will synchronize with grid tie inverter to support loads, the excessive solar production will go back into battery even when the inverter is in DC TO AC discharge mode thanks to Sigineer’s unique bidirectional circuit design.

But is different from the charging stage when it is powered by shore power in its AC input. The inverter willn’t shut off charging until high battery cut off is reached.

When battery voltage goes to high alarm point, our 60/62.5hz frequency switch dry contact allows the inverters to receive an external signal to switch the output freq from 60hz to 62.5hz to temporarily shut off the grid-tie inverters.
Customers can  use a BMS or DC detector to achieve this purpose.

During the GT inverter shutoff, the battery is still being discharged by our AC coupled inverter.

2 AC to DC AC Charge mode
When the battery voltage goes low to alarm, the inverter is able to take AC power from the utility or generator to charge batteries.

Currently, only 4 models of Sigineer Power’s inverter chargers are built with 60/62.5hz freq switch and are suitable for AC coupled system.
These models are

Note: These AC coupled inverter chargers are OFF grid, they can’t send excess energy to sell back to the grid, they only output AC to wake up your grid-tie inverters.

Here is the simplified wiring diagram for AC coupled system.

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