WiremanWireman · Rapid shutdown won’t release: troubleshooting for electricians · 2023 NEC ·
Rapid shutdown won’t release
Initiator, the signal to the module electronics, and incompatible or failed devices.
Before you start
How much electrical experience do you have?
This sets how much detail each step shows. You can change it any time.
Showing detail
How it works
Rapid shutdown lets firefighters drop the voltage on roof-mounted PV conductors quickly. Outside the array boundary the conductors must fall to a low voltage within 30 seconds, and inside it the system must also reduce the shock hazard. Most systems do this with electronics at each module that only pass full voltage while they hear a “keep running” signal from a transmitter or the inverter. If that signal stops, the array stays in shutdown even after the switch is turned back on.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- Is the whole array stuck in shutdown or just one string?
- Whole systemIs the initiator switch on, and has the system had a few minutes to restart?
- Switch was off, now on and workingSystem was shut down on purpose
- Switch is on, still stuckTest: Check power to the inverter or signal transmitterExpect: The voltage on its label, typically 240 V or 120 V.
- No powerTransmitter or inverter has no AC
- Power presentWere any modules, module devices, the inverter or the transmitter replaced or added recently?
- Yes, parts were changedIncompatible rapid shutdown equipment
- No changesSignal transmitter or its coupling has failed
- One stringTest: Measure that string’s voltage in run modeExpect: Close to the good strings. A string near the maker’s shutdown voltage is still in shutdown.
- ZeroOpen in that string
- At the low shutdown levelThat string isn’t receiving the signal
- Between normal and shutdownOne or more module devices failed
- Whole systemIs the initiator switch on, and has the system had a few minutes to restart?