Article 690, consisting of eight Parts, applies to photovoltaic (PV) electrical energy systems, array circuit(s), inverter(s), and charge controller(s) for PV systems. The requirements of Chapters 1 through 4 apply to these installations, except as specifically modified by Art. 690. These systems may be interactive with other electrical power sources or standalone with (or without) energy storage (batteries), as shown in Fig. 1.