With solar becoming a popular option for obtaining energy, many homeowners have begun implementing grid-tie and hybrid solar power systems into their homes. Both grid-tie and hybrid systems give homes two sources of electricity, one from the grid and one from a solar power system. Meaning you’ll have a backup in case your primary power source fails.

For safety and convenience, these grid-tie and hybrid systems often use a device called an automatic transfer switch (ATS). So, what is ATS? What does it do, what are its benefits, and why would you need it?

What is an Automatic Transfer Switch (ATS)?

An automatic transfer switch is a self-acting electrical device that switches between your primary and backup power source when the primary fails. Having an ATS installed with your solar-powered home ensures that you get continuous power without the need to manually switch from solar to grid or vice versa.

Although most often used in solar power systems, ATSs can also be used in many other setups where a home or facility has two sources of power. Whether it’s grid-to-solar, grid-to-battery, or grid-to-turbine, as long as you have at least two power sources, you’ll want to install an ATS.

Benefits of using ATS

Without an ATS, you’ll typically see manual transfer switches installed in various solar home setups. A manual switch allows you to switch between your primary and backup power source when power fails from your primary power source, so what exactly are the benefits of using an automatic switch compared to a manual switch?

continuous power

The main reason you should implement an ATS in your solar power system is that it allows for a continuous flow of electricity within your home even when the grid or your solar generator fails. Depending on the ATS you install, you can also enjoy uninterrupted power where the ATS switches to your backup power source within tenths of a second.

In fact, every uninterruptible power source (UPS) uses an ATS to provide uninterrupted power and protect your computer from damage.


Integrating an ATS into your electrical system allows you and your family to have easy access to power without the need to manually switch on your backup supply. This is especially true for homes where the manual switch is located in attic basements or other hard-to-reach areas of the home.


Some ATS can also be set up to power only select areas or electrical appliances in the home. This is important because backup power usually comes in limited supply.

This means you can’t just power your home at 100% capacity, because you don’t want to burn through your stored electricity too soon. Having an ATS and setting it up to only provide power to certain areas of the home is a great way to save energy during a power outage.


Manually switching between primary to power backup in dark environment is dangerous. Worst of all, you may not even be at home when the power goes off. It would be disconcerting to let your unregistered family member fumble with the panelboard trying to find the manual transfer switch. Having an ATS eliminates the need to manually operate the switch which makes it a safer alternative over a manual transfer switch.

Types of ATS

There are different types of ATS being sold in the market today. Understanding the different types will help you make a better decision on which type of ATS you want for your specific needs. Here are the four most common ATS types:

Open Transition ATS: Also known as a break-before-make switch, this type of ATS systematically disconnects your electrical wiring from your primary power source before connecting it to your backup.

This method of switching is the safest but also the slowest switching method, with a downtime of about one second. This ATS is best for those who want utmost security and reliability from their ATS.

Closed Transition ATS: Unlike open transition ATS, which is connected to only one power source at a time, a closed transition switch is connected to both power sources continuously.

This allows for low latency switching for uninterrupted power. This type of ATS is a great option for those who require uninterrupted power for plugged memory sensitive devices such as desktop computers, game consoles and 3D printers.

Soft-loading transfer switch: This type of ATS contacts both power sources in the same way as a closed transition ATS. What makes this type of ATS unique is its ability to use both power sources at the same time.

Soft-loading ATS uses an active synchronizer to gradually transfer power from the primary to the backup. Until then, this type of ATS allows the primary to keep powering equipment until its voltage can keep up with demand.

Leave a Reply

Your email address will not be published. Required fields are marked *