Will a generator work with my battery backup system?

System Integration Basics

A generator can provide supplemental power to a battery backup system during extended outages or when the batteries are depleted. To integrate a generator with your Powerwall or Enphase EG4 system, you’ll need a transfer switch and possibly a generator controller, depending on the system’s configuration. A transfer switch automatically switches between the grid, generator, and battery backup sources based on the system’s state and your preferences.

Generator Sizing and Connection

When selecting a generator, consider the total power requirements of your critical loads, including the system’s inverter and transfer switch. As a general rule, the generator should be sized to handle at least 20% more power than the system’s maximum demand to account for startup surges and inefficiencies. For example, if your system’s maximum demand is 5 kW, a 6 kW generator would be a suitable choice. Connect the generator to the transfer switch, which will automatically switch to the generator when the grid is unavailable and the batteries are depleted.

Automated Transfer and Control

To ensure safe and efficient operation, consider implementing an automatic transfer switch that can monitor the grid, generator, and battery backup sources. This can be achieved using a system like the Honeywell Home T9 or the Square D by Schneider Electric 100 Amp Main Breaker Transfer Switch. The transfer switch will automatically switch to the generator when the grid is unavailable and the batteries are depleted, and switch back to the grid when power is restored. This ensures seamless operation and reduces the risk of damage to either system.