AC vs. DC Basics
- DC (direct current): current flows in one direction. PV modules produce DC.
- AC (alternating current): current changes direction periodically (in the U.S., typically 60 Hz). Homes and the grid use AC.
Why PV uses an inverter
A grid-tied PV system uses an inverter to convert DC from the array into AC synchronized with the utility grid.
Common exam focus
- Identify where DC exists vs where AC exists in a system
- Understand that switching/isolating AC does not automatically de-energize DC sources