Photovoltaic power system inverter detection apparatus and methods are disclosed. Electrical continuity between an inverter in a PV power system and a PV panel disconnect switch, which switchably couples one or more DC PV panels to the PV power system, is tested while the PV panel disconnect switch is open. A state of the electrical continuity is determined based on measurements of an electrical parameter after the test signal is applied. The PV panel disconnect switch is maintained open on determining no electrical continuity, and closed on determining that there is electrical continuity between the PV panel disconnect switch and the inverter. A shutdown device that implements inverter detection may be located and/or adapted to meet safety conditions, by being located less than 10 feet from the PV panel array and/or adapted to limit a test signal to a maximum of 30V and 240VA.