What Is a Solar Isolator Switch, and Do You Need One?

Solar energy systems are a wise investment, but must be safely installed and managed. The solar isolator switch is one of the most important yet often overlooked components.

Whether installing a new system or adding battery storage, understanding how isolator switches work and why they matter can help keep everyone safe, protect your home and equipment, and offer peace of mind.

This article will explore what they are, if and when you need one, why they are necessary, and how best to choose the right one.

A solar isolator switch is a safety device that allows you to manually disconnect the direct current (DC) electricity from flowing in different parts of your solar system. There are two types of switches. One is located between the solar panels and your household electricity, which should be placed in an accessible location, but is sometimes placed right next to the panels, which could be high on a roof. 

The other type is a solar battery isolator switch, which disconnects the electricity between your EcoFlow Power Ocean (Single-Phase) battery storage system and your inverter, which typically avoids the accessibility issue.

The isolator switch is a vital safety component of any solar system. It ensures the safety of those working on or around a system by preventing electrical accidents and other safety issues. 

Without an isolator switch, even trained electricians could make assumptions based on how they think the system is set up, assuming it is safe. However, if the system is not set up exactly according to regulations, it could still result in live electricity, risking electrocution and fire. 
Introducing solar batteries can further complicate the risk since a DC battery should always be considered live. For these reasons, solar isolator switches should always be used, whether you have batteries or not. 

To ensure safety, a switch must be adequately sized for your particular array, have a dust and water ingress rating of at least IP65, and be located in an accessible location to make it easy to turn off the power from your array if needed. Using high-quality products with excellent manufacturer warranties, like those offered by EcoFlow Home Battery, will further help ensure the safety, performance, and longevity of your system. 

Also, if you have more powerful three-phase electricity in your home, ensure you use products like the EcoFlow Power Ocean (Three-Phase), which are explicitly designed for three-phase systems. 

Yes, solar isolator switches are legally required in the UK. According to the G98 regulations for systems under 16kW, your solar system should be “connected via an accessible isolation switch that’s capable of isolating all phases and neutral. The isolation switch shall be capable of being secured in the ‘off’ (isolated) position.”

The G99 regulations for larger systems over 16kW are more complex, but the ability to isolate your system is still required. 

If your system is designed to operate in parallel with a public low-voltage distribution network, aka on-grid systems, you will need an isolator switch. If yours is off-grid or larger than 16kW, consult the EREC G99 regulations for more information.

This means that the odds are high that you will need an isolator switch with or without solar battery storage systems. If you have an existing array and are adding a new battery storage system using the EcoFlow PowerOcean DC Fit, it is always a good idea to consult a certified electrician to ensure the appropriate isolator switches are installed.

In fact, you should almost always hire a certified electrician to install your system if you lack significant electrical skills or knowledge of the rules. It will ensure it’s done according to all the latest safety standards and legal requirements. Depending on where you live, if you are connecting to the national grid and applying for any rebates or credits, a certified electrician may already be required. 

The size switch you need depends on your system's maximum output current and voltage, since it must be able to handle the full short-circuit of your solar array with a safety margin. The size will also vary depending on whether you have single-phase or three-phase electricity. Your electrician will help you determine the correct size. 

An isolator switch is a safety device used to ensure that electrical circuits are de-energised for repair and maintenance. When the switch is “off”, it creates a physical break in the circuit, stopping the flow of electricity and preventing accidents like electric shocks.

The isolator switch size depends on your solar system's maximum output current and voltage. It must be rated to handle the full short-circuit of the solar array with a safety margin. Also, single-phase inverters may have a voltage of up to 600V, while three-phase systems could be 1500V.

A solar isolator switch should be located on the DC side of the inverter (where the DC wires enter the building), and another switch should be placed near the solar panels themselves. This positioning means that disconnecting the panels should be fast and straightforward, which is key for maintenance and emergencies.

Solar isolator switches are not just an added safety feature but a legal requirement for most on-grid solar systems in the UK. They protect electricians, homeowners, homes, and equipment by providing a simple, secure way to isolate the power when needed so that you can work on or around the system. 

Whether installing a new array or upgrading your current one with a battery storage solution like the EcoFlow Power Ocean (Single-Phase), make sure you have an isolator switch that is sized correctly to handle the full short circuit of the system and meets current regulations. For most of us, that means consulting a certified electrician to ensure it is done correctly and safely.