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Solar automatic transfer switch
Solar automatic transfer switch
Resource: https://www.youtube.com/watch?v=yzVt-YWxJR0

A solar automatic transfer switch allows you to use a PV system alongside a backup power source. Easy to install, it also offers the advantage of automated operation and a safer switching method between your solar system and an alternate power source. This article aims to help you understand the automatic transfer switch for solar power backups in more detail.

What is a Transfer Switch?

If you’re new to the transfer switch, here’s what it is: A power transfer switch is an electrical device used to safely connect or disconnect a load from its primary power source to another.

In the case of a solar system, the load is the home or business that the solar array is powering and the alternate power source is the grid or grid generator.

The transfer switch function is to ensure the continued supply of power to electrical loads. It does that while ensuring no more than one power source is connected to the load at any given time, as that could cause an electrical hazard. There are two main types of transfer switches:

A manual switch requires the user to be present so they can manually toggle the load between the power sources. An automatic transfer switch, ATS, does that automatically, in your absence. Read more about the solar ATS below.

Solar power automatic transfer switch
Solar power automatic transfer switch
Resource: https://youtu.be/babtv00R-Nc

Solar Automatic Transfer Switch

A solar automatic transfer switch is a type of self-acting switch that is specifically designed for use with a solar power system. Solar ATS are typically installed so they connect to the grid, inverter, solar battery, and the load.

When battery power goes down, the solar transfer switch will automatically connect your appliances to the grid. This ensures your electrical system continues to operate even when there is no solar power available.

A solar power transfer switch is an important part of a PV system. It provides a safe and reliable way to connect or disconnect the solar array to the grid. Without you, would need to manually do the toggling. You can use these switches in different solar systems, as explained below.

Grid Tie Solar Transfer Switch

A grid-tie solar transfer switch is specifically used with a grid-tied solar power system. That means it allows your system to draw power from the grid when necessary, such as during bad weather.

These solar transfer switches are typically mounted between the utility meter and the solar inverter. The switch will then monitor both sources, and connect to the alternate source whenever necessary – without requiring manual operation.

Another advantage of a solar-to-grid switch is that it doesn’t feed power to the grid as that could cause danger to utility crews. Instead, it only draws electricity from the mains to power your loads when the batteries are depleted.

Off Grid Solar System Transfer Switch

In some cases, the solar system does not connect to the grid. So the auto solar transfer switch must toggle the load between the PV system and a different source, such as a generator.

But solar inverters usually come with built-in mechanisms to switch between power sources. So, where would you need the transfer switch? The answer is, in these situations:

  • When the inverter cannot serve the specific load because its power rating is too low. In this situation, you would want to bypass the inverter and use an external transfer switch instead.
  • In situations where you want to connect to two backup sources (such as the utility and a generator) but your inverter can only allow one source to be connected.

You can also use the automatic transfer switch for off-grid solar systems in different electrical systems, whether residential or commercial. That said, the off-grid switch is more common in remote locations where it is not feasible to run a utility line. Also, in RVs when connecting to shore power or generator.

RV Solar Automatic Transfer Switch

An RV solar automatic transfer switch is installed in an RV. Here, it provides a convenient means to connect or disconnect your loads from solar power to shore power. That way, your RV can remain powered even when the solar system is not producing electricity.

The RV transfer switch may also be used with other types of power sources, such as a generator. The switch will automatically connect the RV to the solar array when the vehicle can receive direct sunlight.

When the battery is low in power, such as during overcast days or after heavy solar usage, the RV solar ATS will automatically disconnect from the solar system and connect loads to the generator.

Solar automatic changeover switch wiring diagram
Solar automatic changeover switch wiring diagram
Resource: https://www.youtube.com/watch?v=O1KuDeh3bno

How does a Solar Automatic Transfer Switch Work?

The solar auto transfer switch uses clever electronics and a switching mechanism to connect to a preferred source. This ensures a continuous supply of power to an electrical load, regardless of if the primary source is working or not. Here is what happens:

  • The solar ATS monitors the primary source which is, in this case, is the solar system storage battery
  • Upon detecting a low voltage (which can be programmed a preferred value) it initiates a switching action to connect the load to the alternate source
  • When the primary power source (solar) is back to normal, the switch detects the return and automatically transfers the load to it

As already indicated, an automatic transfer switch for solar power systems may allow users to program its operation mode. For example, you may be able to set the minimum voltage that should cause a load changeover. This would help to protect the batteries.

Another common feature of a solar power transfer switch is the provision for manual control. This is usually a toggle switch that you rotate to select the default power source or even override the auto function.

A type of solar automatic transfer switch
A type of solar automatic transfer switch
Resource: https://powerforum.co.za

Best Automatic Transfer Switch for Solar

What is the best automatic transfer switch for solar systems? This is a common question when looking to buy transfer switch equipment. And the answer is that it depends. The auto-transfer switch for solar is available in a variety of different sizes and configurations.

It’s also available in many different ratings for voltage. The right automatic changeover switch for solar power backups will, therefore, be dependent on several factors such as:

  • The specific application or use case
  • The number of circuits that need to be powered
  • The maximum amperage and voltage that the switch can handle

Other considerations when choosing the best automatic transfer switch for solar systems may include things such as:

  • Ease of installation – you want a model that is easy to install, especially if you are doing it yourself
  • Ease of use – you want a model that is easy to use, especially if you are not an electrician
  • Price – you want an affordable model without compromising on quality or features

There are also different automatic transfer switch brands out there. Therefore, in addition to the factors mentioned above, you may want to consider the brand or manufacturer when making your final decision.

Installing solar automatic transfer switch
Installing solar automatic transfer switch
Resource: https://www.youtube.com/watch?v=IaeNkSG5-uk

Solar Automatic Transfer Switch Installation

An automatic transfer switch for solar is one of the easiest to install, with most types of the switch plug-and-play gadgets. It usually only requires a few wires, and comes with easy to follow instructions. The installation process is also typically the same for most switch models.

Here are installation steps for a home automatic transfer switch if looking to link your solar system to an alternate power source such as utility grid. Note that these steps apply to the type of solar ATS that does not require complex wiring.

1. Decide where to install your solar auto changeover switch. This will be determined by the type of electrical panel you have. The switch must be mounted a safe height above the ground, and away from any flammable materials. Ensure plenty of ventilation, too.

2. Disconnect the main power supply to your home. This is usually done by flipping the main breaker in your electrical panel to the “off” position.

3. Wire switch according to the instructions that come with it. This will involve connecting wires from the switch to the following:

  • The grid
  • The solar inverter
  • The solar battery

The switch will come with connection points or terminals for the wires, which makes the task easier.

4. Mount switch. Once everything is properly wired and switch installed, you can then reconnect the main power supply to your home. Be sure to flip the breaker in your electrical panel back to the “on” position.

5. Test automatic transfer switch by disconnecting the power from your solar system and making sure that the switch properly transfers the power to your backup generator.

With most models of a solar battery or solar panel automatic transfer switch, the installation process is relatively simple and can be done by anyone with basic electrical knowledge.

However, if you are unsure about any part of the installation process, it is always best to consult with a professional electrician. A qualified person will ensure that everything is installed correctly.


A solar automatic transfer switch can be a vital addition to your PV system. It allows you to use solar power as the primary source and switch to alternate power such as utility or generator when necessary. When looking to use one, we recommend getting a model that matches the requirements of your power system. Make sure to install your ATS according the provided instructions to ensure it works properly.

IGOYE Automatic Transfer Switch Catalog