In various embodiments, the heartbeat indication can be provided to the modules in a variety of ways. For example, an electrical signal can be imposed on the array, such as a time-varying current, which can be detected and discriminated from noise or other outside influences by sensing circuitry. As one specific example, power-line communication (PLC) can be used to transmit or receive a variation in the module's voltage or current between the remote device and module. PLC can be used to send a heartbeat indication such that a periodic indication can be sent to multiple modules causing the multiple modules to remain enabled for a predetermined amount of time (e.g., 10 seconds, 15 seconds).

The remote transmitting device can be the inverter, combiner box, or some other component, as described herein. In an embodiment in which the inverter is the device transmitting the heartbeat indication, a specific heartbeat circuit can be included in the inverter to provide the heartbeat or the heartbeat indication can be produced by altering the normal operation of the inverter circuitry.

Examples of variations to the normal operation of the inverter include changing the timing and/or magnitude of maximum power-point tracking (MPPT) steps, causing the array's operating point (and its voltage or current) to vary according to a predetermined pattern (but in a way that has a small effect on the power produced by the inverter), or applying a voltage to the array, even if the array cannot produce usable power (e.g., before sunrise).