In some embodiments, indication 142, such as a heartbeat indication, can be sent to all modules in the array, a subset of the modules, or to a single module. In some embodiments, some combination of local and external controllers can be used to engage and disengage the modules. For instance, determination of whether to enable or disable a module can be performed by a local controller based on an indication provided by a central controller. In some embodiments, controllers can coordinate with one another such that enabling or disabling is consistent in the array. For example, if a single local controller missed an indication to shut down, the other local controllers can share the shutdown signal with that single local controller to help ensure shutdown takes place. Note that such coordination need not take place for an entire array. For example, in some embodiments, system level coordination can refer to a system of PV modules coupled to some downstream hardware, such as an inverter, combiner box, etc.

In some embodiments, inverters are powered solely by the PV array and cannot send an enable indication to the modules before some or all of the modules become enabled. In such embodiments, a separate startup circuit can be used to send an enable indication to one or more modules in the array to become enabled so that the inverter can begin operating. The startup circuit can be built into the inverter enclosure but can be separate from the inverter's power production circuitry. In one embodiment, the startup circuit can use the AC power grid connection at the inverter's output as a power source. In some embodiments, the startup circuit can send the initial startup indication and the heartbeat indication during normal operation, or it just can send the startup indication before the inverter's normal operations.