How the Automatic Shut Off Switch Works

Solar Inverter
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How Solar Inverters Work
Last Updated: April 29, 2021  

When people think of installing solar, they envision complete independence from the grid. However, this setup usually is the exception of solar installations, not the rule.

Since solar arrays can’t store energy, other options need exploring. Battery backup has become commonplace in solar homes, but for many, whole-home energy storage isn’t a financial option. Most solar homeowners stay connected to the grid, especially if the utility offers net metering.

Staying connected to the grid allows customers to use it when solar panels can’t cover all the necessary production. However, when the power grid goes down, everything connected to it does too.

Solar Power During an Outage

It would make sense for a solar array to continue running during a daytime power outage. However, this isn’t what happens, and for good reason. It is against metropolitan and municipal fire code for solar panel systems connected to the grid to stay on when the grid’s down, which demands a rapid shut down mechanism in solar panels.

Rapid Shutdown Requirements

Rapid shutdown shuts down the solar array as soon as it detects that the grid in the area isn’t working. Essentially it stops power from going onto the grid, preventing linemen from getting hurt while trying to fix power line issues. The problem is that it also shuts off solar power to the house.

Rapid Shutdown Solutions

The rapid shutdown switch is normally on the inverter. Go Solar Group uses the SolarEdge inverter.

Rapid Shutdown: SolarEdge

The SolarEdge, a commonly used solar inverter, will disconnect from the solar modules if it detects grid failure. However, if a manual shut-off is required, a mechanism on the inverter will allow it. Start by turning the inverter on/off switch at the bottom to the off position.

Once the voltage has gone down below 50 volts of direct current (DC), turn off the DC safety switch. Once completed, the alternating current (AC) can turn off.

Rapid Shutdown Requirements Effective January 2019

The requirements for rapid shutdown received an update in January 2019. It’s now required to adhere to NEC 2017 instead of NEC 2014. This new regulation requires a module-level shutdown.

All conductors within a foot of an array now have to reduce to 80 volts within 30 seconds during an outage. This new requirement increases the safety of firefighters should they have to enter a home through the roof.

NEC 2017 Requirements’ Effect on Future Inverter Shut Off Switch

Before NEC 2017, inverters could cut off power at the inverter. The solar panels, however, could still generate a current.

Inverter companies, such as SolarEdge, have updated their products to comply with these regulations. However, these changes make it more difficult for solar to power a home during an outage.

Future Power in an Emergency

Solar batteries can avert this crisis. They allow individuals to access solar whenever they want. 

If they have a home battery, like the Powerwall, it takes over during outages. As a result, the homeowner may not even know there was an outage.

Go Solar Group has several affordable backup solutions. These batteries and other backup solutions give individuals the ability to customize their energy storage to their specific needs.

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