Connecting to external AC PV inverters
The Multi RS includes a built in AC PV inverter detection system. When there is a feedback of AC PV (a surplus) from the AC-out connection port, the Multi RS will automatically enable an AC output frequency adjustment.
While no further configuration is required, it is important that the AC PV inverter is configured correctly to respond to the frequency adjustment by reducing its output.
Note the 1:1 rule of AC PV inverter size to Multi RS size, and minimum battery sizing applies. More information about these limitations are available in the AC Coupling manual, and this document is required reading if using an AC PV inverter.
The frequency adjustment range is not configurable, and includes a built in safety margin. Once the absorption voltage is reached, the frequency will increase. So it is still essential to include a DC PV component in the system for complete battery charging (i.e. float stage).
The PV inverter stop frequency (fstop) is 53.2Hz. This is not configurable.
It may be possible to adjust the power output response to various frequencies on your AC PV inverter.
The default configuration has been tested and works reliably with the Fronius MG50/60 grid code configuration.