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Solar Rapid Shutdown For Owners
Rapid shutdown is a safety feature for firefighters. As a homeowner you may see its labels, a switch or labeled disconnect outside the building, or the term on a repair quote. This page explains the idea in plain terms. It is not installation guidance, and codes differ by edition and by city.
What It Is For
The Mike Holt Enterprises excerpt of National Electrical Code 2020 section 690.12, from a code textbook publisher, says PV system conductors on or in a building must be controlled by a rapid shutdown system to reduce shock hazard for firefighters. The Department of Energy guide to fire safety with solar systems describes the firefighter sequence as finding the solar system on the structure, shutting it down, watching for hazards while extinguishing the fire, and making the scene safe when leaving.
The Numbers In The 2020 Code Excerpt
The excerpt says that, for rapid shutdown, the array boundary is the area 1 foot outside the perimeter of the PV array. It gives these limits:
| Where | Limit Stated In The Excerpt |
|---|---|
| Outside the array boundary, or more than 3 feet from where conductors enter the building | 30 volts within 30 seconds of initiating shutdown |
| Inside the array boundary | One of three options in the excerpt: a listed PV hazard control system, 80 volts within 30 seconds of initiating shutdown, or an array with no exposed wiring or conductive parts that sits more than 8 feet from exposed conductive parts |
We read only the 2020 edition excerpt. Earlier and later editions use different wording, and your city may enforce a different edition. Ask your building department which one applies to your system.
The Initiation Device
The excerpt says a rapid shutdown initiation device can be the service disconnect, the PV system disconnect, or a readily accessible switch that plainly indicates whether it is in the off or on position. For houses, the excerpt says the device must be outside the building at a readily accessible location. Your installer's paperwork or the inspection record should say which device yours is, and where it sits.
Microinverters And Optimizers
Because the rule limits voltage inside the array boundary, equipment type matters. Enphase says its microinverter systems have built in rapid shutdown capability and that a single switch shuts the system down. The EnergySage overview of microinverters says microinverters do not require power optimizers for rapid shutdown compliance, and Enphase says string inverters need additional equipment for it. These are statements by an equipment maker and a consumer site, so check your own system's documents.
What Owners Should And Should Not Do
- Find the switch or label on your system and keep photos of it with your records.
- Do not operate the shutdown switch to test it. If it has been used, ask your installer or the manufacturer how the system should be restarted, since procedures differ.
- Do not remove, cover, or paint over required labels during a reroof or siding job. Tell contractors the system exists.
- If you add panels or a battery, ask the installer how the shutdown will be handled. See Add A Battery To Solar You Already Have.
If the shutdown seems to have tripped on its own and the system will not restart, photograph the lights and read Solar Inverter Lights And Error Codes.
If you want a local service company to look at your system, describe it in the system check form. We name the one company before anyone contacts you.
Related: Solar Monitoring, Repair, And Inspection, Solar Inverter Replacement, Removing Solar Panels For A New Roof, Solar Warranty Help.
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