A controller circuit for a PV module includes a receiver circuit and a mode control and power conversion circuit. The receiver circuit receives a first signal from a transmitter circuit and changes a second signal from a first state to a second state responsive to the first signal. The mode control and power conversion circuit receives a DC voltage from a string of PV cells, receives the second signal from the receiver circuit, switches from a first mode to a second mode in response to the second signal being in the second state, converts the DC string voltage to a standby voltage in the second mode, and provides the standby voltage to DC power lines. The standby voltage is less than an operating voltage provided by the mode control and power conversion circuit in the first mode.