Some homes have more than one solar inverter. There are several different ways in which two (or more) inverters may be installed and monitored. Charge HQ supports some setups, but not all. In all cases, Charge HQ obtains solar monitoring data from a single "source" only, eg from a single monitoring app such as Fronius. But this is often enough to support a 2nd inverter, even of a different brand.
If your main inverter monitoring can see the generation from both inverters, ie they are combined, this will work with Charge HQ. If you have a consumption meter, this will work too.
This setup typically involves:
In this case, your 1st inverter has a consumption meter, which means it measures grid import and export, and the 2nd inverter is not visible to the 1st inverter. In this case your household consumption will often be reported as negative, ie when the 2nd inverter's generation exceeds your actual household consumption. The grid import and export is reported correctly.
This case is supported by enabling the Negative Consumption setting in Solar Tracking Settings. Charge HQ should automatically detect this case and enable the setting for you.
If your solar monitoring only shows the generation from one inverter, and does not show household consumption or grid imports and exports, then Charge HQ can only track the generation of the 1st inverter.
If your inverters are each monitored separately and there is no consumption meter, Charge HQ can only track the solar generation of one inverter. Charge HQ can not combine data from multiple sources. In this case the best option is to connect Charge HQ to your largest solar system.