What Is Solar Rapid Shutdown And Why Do You Need One For Your PV System?

Home What Is Solar Rapid Shutdown And Why Do You Need One For Your PV System?

If you recently installed a solar panel system, you might have noticed a box named rapid shutdown with an on/off switch. But what do you mean by a rapid shutdown switch and why is it important for a PV system? 

In this article, you will learn about the requirements of rapid shutdown and how you can comply with the code of your state with the safety of your solar panels.

What Is A Rapid Shutdown Device?

Module Level Rapid Shutdown
Source: Beny

A rapid shutdown is a regulation that makes it necessary for solar power systems to have a solar panel shut-off switch. In simple words, a rapid shutdown is a speedy way to de-energize your solar system in case of emergencies.

It was first implemented as a safety precaution in 2014 by the National Electrical Code to offer a fast way to cut off the running electricity through the system. The intention behind this regulation was to provide a method for firefighters to remove the power source during a fire. Later, some changes were made to the requirements of the NEC 2014 code for a rapid shutdown.

In 2017, the meaning of rapid shutdown was expanded with different requirements based on the closeness of the PV system conductors to the PV array boundary. The PV circuits that are located more than 3 feet away from the entry point of the building would not be limited to not more than 30V within 30 seconds of initiating the rapid shutdown.

The PV circuits that are located inside the boundary of the array need to execute one of the following three options:

  1. The PV array should be listed as a rapid shutdown PV array and should be used and installed in accordance with PV listing instructions.
  2. The PV conductors that are located within the boundary shall be limited to 80V within 30 seconds of initiating the rapid shutdown.
  3. PV arrays that are not exposed to wiring methods or conductive parts and are installed above 8 feet of exposed grounded conductive parts would not be required to abide by rule 2 mentioned above.

What Is The Importance Of Rapid Shutdown?

Solar system
Source: Pinterest

There is live electricity running through your solar plant when the sun is shining bright in the sky. It is entirely safe in most situations because it runs from the panel to your inverter. However, in emergencies the conduits can be damaged, exposing them to live electricity and creating a dangerous situation.

With the function of a rapid shutdown, the firefighters can quickly cut the power off in the conduits, making it safe for them to access the area around the PV system. Once they can safely access the area, they can detect and solve the problem without any risk of electrocution or fire.

A photovoltaic system has conductors that carry current any time the sun is shining and without a rapid shutdown device, there is no safe way to turn off the running current in those conductors. There isn’t time to deal with the solar conductors in times of emergency. Consequently, the NEC guidelines of the rapid shutdown system help protect your PV system effectively.

The National Fire Protection Association wrote the requirements of the rapid shutdown into NEC in order to keep the first responders safe. Hopefully, you won’t have to face fire and worry about the function of the rapid shutdown, but if the fire catches on the firefighters can de-energize your solar system in case they need to go to the roof.

Surprisingly, just turning the solar inverter off doesn’t always turn out to be enough. Some inverter setups and wires remain energized even after turning the inverter off. This increased the risk of shock for the first respondents working on the roof. Having a switch that disconnects the power entirely, allows you to turn your solar panels to a level of safety in under a minute.

Is It Necessary To Have Rapid Shutdowns Everywhere?

Solar PV system with rapid shutdown
Source: Pinterest

If your system was installed way before the implementation of the safety codes by NEC, then you do not need to get the rapid shutdown switch installed. It is not required to have rapid shutdown systems everywhere at this point, but it is a safety feature so it is a good idea to have one installed irrespective of whether your state enforces it or not. 

The National Electrical Code releases a set of requirements every three years for the safety of electrical systems that need to be followed. The NEC is not mandated federally which is why the state takes its time to adopt the code. Some of the states select an independent electrical code instead. You need to determine what are the requirements for a rapid shutdown in your state.

As of 2021, each state in the USA enforces the NEC or its own version of the code. If your state enforces the 2014 or newer NEC code, your PV system will have to follow the rapid shutdown requirements to pass the final inspection of the system and get it connected and running.

Here are a few things that you can do to pass the solar inspection test easily:

  • Install the solar kit correctly in compliance with the safety standards
  • Document the changes that you made to the system and make sure that the changes have been approved
  • Make sure that the wiring inside is visible 
  • Prepare for the inspection in advance by providing safe access to the solar panels
  • Keep the stamped copy of your solar permitting plans ready

Specific Requirements Of Rapid Shutdown

Solar rapid shutdown
Source: Pinterest

To abide by the NEC code, your solar rapid shutdown procedure needs to meet some specified criteria which vary depending on the state that you are living in. Just make sure that you get your safety devices from a renowned company that offers quality products. Some companies even offer their expert advice on which systems to buy for your house.

There are two specific codes – NEC 2014 and NEC 2017 both of which are applicable in different parts of the world.

NEC 2014

The requirements of the rapid shutdown were first mentioned by NEC in 2014 for the safety of PV systems. The NEC 2014 code states that the controlled conductors farther than ten feet of the solar panels should be brought down to 30V and 240 volt-amperes within 10 seconds of rapid shutdown switch initiation.

Let’s have a broader look at this code. The controlled conductors transmit AC or DC current from the solar panel components, given that they are farther than 10 feet from the panels. Any conductor within ten feet of the solar panels or the array can maintain power after the switch is initiated.

This applies only to solar conductors that are longer than 5 feet in length inside the building, or farther than 10 feet from the solar power system. Additionally, the device should be clearly labeled saying “rapid shutdown device”, along with the other parts of the solar system.

Some of the PV systems utilizing string inverters can comply with the NEC 2014 rapid shutdown code without a shutdown switch. If the string inverter is located within 10 feet of the panels, then you won’t have to get conductors extending beyond 10 feet.

NEC 2017

If your state complies with the NEC 2017, you will have to abide by the expanded requirements regarding the rapid shutdown. The NEC 2017 requires you to de-energize any conductors beyond 1 foot of the array using a rapid shutdown switch as opposed to the 10 feet zone of NEC 2014.

The solar components inside the one-foot boundary should be limited to 80V within 30 seconds of initiating the shutdown device. It is easy to comply with this code with module-level rapid shutdown switches. The changes in 2017 stipulate that the rapid shutdown should occur at individual solar modules instead of solar array as a whole.

The 3 ways to comply with the 2017 NEC code includes:

  • Installing a “listed” or field-labeled rapid shutdown system
  • Installing a system that is capable of lowering its voltage to 80 volts within 30 seconds
  • Installing a BIPV system without any metal components or exposed conductors

Is It Necessary To Comply Your Old System with New NEC Versions?

Solar panel system
Source: Pinterest

You do not need to retroactively install a rapid shutdown button on your system if your solar panels were installed years before the NEC came into action. That being said, if you want to expand your solar system or make changes that require inspection, you may have to update your system in accordance with the NEC regulations, which may include the rapid shutdown switch.

Installing the rapid shutdown switch will add a layer of safety to your solar system in case of emergencies. So even though it may not be necessary to install a rapid shutdown switch, it is recommended for safety purposes. You need to make sure that your system is upgraded keeping in mind the requirements of the rapid shutdown in your state.

Do All Inverters Have Rapid Shutdown Facilities?

Source: Pinterest

Some of the inverter systems are compliant with the shutdown requirements but others require additional components to initiate the rapid shutdown. Microinverters and power optimizers have in-built shutdown capabilities. If you have a string inverter, you may need to install module-level devices to comply with the 2017 NEC code.

You need to determine if your system is compliant with the rapid shutdown requirements before you make any changes to your solar panel system because you will be inspected for the same. You can take the help of a professional to choose the correct rapid shutdown components for your system.

Installing the Rapid Shutdown Switch

Installing a safety PV system
Source: Pinterest

Solar panels are not unsafe to first responders per se. If your system was installed before the rapid shutdown was implemented, it does not pose risk to you or the building. However, it is worthwhile to install the rapid shutdown switch as per the local guidelines of your state. Not all inverters support the rapid shutdown, so you need a professional to help you with it.

It is advised to get a professional to install the rapid shutdown switch with expertise. This way you won’t have to worry about the changing codes of your state. You can easily get an updated version of the system in accordance with the current code of safety of the PV system. This will help you get through the inspection without any glitches.

It is also possible to install the rapid shutdown switch by yourself if you have the right guidelines and right tools for it. If you choose to install the system by yourself, make sure that you abide by all the rules of your local state regarding the rapid shutdown device.


The requirements of the NEC 2017 represent a step forward in the safety of PV systems. There are various designs and products available in the market that complies with the control requirements of the NEC code. Stay safe and keep your PV system safe with the rapid shutdown system. 

If your state has codes for the safety of your PV system, then you need to make sure that you update your solar system in accordance with the new guidelines of the rapid shutdown device of your state.

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