If RCR is used, is it necessary to connect meter?

Yes, if you are using a Ripple Control Receiver (RCR), it is typically necessary to have a meter connected for monitoring and data collection. The meter helps track the power flow, especially in on-grid systems where grid management and performance analysis are crucial. It ensures accurate measurement of energy generated by the system and allows for proper integration with the utility grid. In some cases, like hybrid inverters or when implementing export control functions, a second meter may be required to monitor the separate inverter's power output.