In a PV system, it’s usually necessary to have a switch that can isolate the PV panels from the system —or the inverter from the grid and loads. This is mainly done using a solar isolator switch. This switch allows you easily (and safely) turn off your solar circuits whenever necessary. The solar isolator, its types, and how it works in your PV system will be explained in this article.
Isolator Switch Definition
Before we can get into the details, let’s define what an electrical isolator switch is. An isolator switch is any type of electrical switch that can be used to isolate a circuit so that no power passes through it. This disconnects any electrical current and turns off all the power to the circuit.
An isolator switch is usually used for safety, or when performing maintenance or repairs on a circuit. The types of isolator switches can vary, but some of the most common include single-pole isolator and double-pole —also referred to as a three-phase isolator switch.
Most often, an isolator switch is a box-like device mounted on the wall with a single handle. When the isolator handle is in the “off” position, power will not pass through any of the circuits connected to it. The isolator switch can also be used to control multiple circuits from one location by using a multi-pole isolator switch.
Solar Isolator Switch
A solar isolator switch is a type of switch that’s solely intended for use in solar systems. It’s similar to any other type of switch, but it has special features that make it suitable for solar PV systems which, in essence, contain both AC and DC currents.
Just like other types of isolators, the isolator switch for solar systems provides a means for disconnecting the various circuits within the system from each other. This is especially important for safety during maintenance, but also for ensuring that your system meets all relevant safety regulations.
Types of Solar Isolator Switches
There are two main types of solar isolator switches: DC and AC. The type you use depends on the side of the system being isolated, and whether the current is direct or alternating.
DC isolator switches are designed to isolate direct current circuits and generally have one pole with two positions: “on” and “off”. These can be used to isolate solar panels, batteries, charge controllers, etc. from other parts of the solar system.
AC isolator switches are intended for use in AC systems such as those connected to the grid. They usually have two or more poles, and can be used to isolate solar inverters from the main grid or any other AC circuits in a PV system.
DC Isolator for Solar
A DC isolator switch is designed to be installed in the DC side of a PV system, between the PV array and the inverter or next to the battery. It is used as an emergency shut-off switch for maintenance or troubleshooting purposes, so it can easily be switched off. When the isolator switch for solar panels switch is in its “Off” position, any current flowing from the PV panels to the inverter is completely blocked.
Isolator Switch for Solar Panels
The isolator switch for solar panels is meant to isolate the solar panels, and can also be called a PV array isolator switch. It’s typically installed between the PV array and the inverter, so it can be switched off if necessary.
In addition to proving safety, and depending on your region, the solar panel isolator may need to meet local safety regulations. Generally, when installed outside, a PV isolator switch must be corrected rated on the on the basis of the local environment.
Solar Battery Isolator Switch
The solar battery isolator switch is used to isolate the batteries from the system. These switches are normally installed on the positive side of the battery. Here, they allow you to quickly and conveniently disconnect the battery whenever necessary.
This type of solar isolator switch is especially useful if you have a battery-based system, if you have your solar system installed in a boat or motor home. In these situations, the switch isolates the battery when the boat or RV is parked.
AC Isolator for Solar
An AC isolator switch is designed to be installed in the AC side of a PV system, between the grid and the inverter (in a grid tied system) and between the inverter and the loads (in an off-grid system). Its main function is to disconnect the AC power from the grid or loads in case of emergency or repair needs.
Grid Isolator Switch
The grid isolator switch in a grid-tied system is used to completely isolate the solar inverter from the public grid. It provides an extra layer of safety, as it allows you to quickly and easily disconnect the PV system from the grid in case of an emergency or for maintenance purposes.
In a storage-based solar system, you do not need the grid isolator. Instead, you need the battery and solar panel isolator. These must be rated for DC current since the power to be isolated is DC.
Inverter Isolator Switch
As mentioned before, the inverter isolator switch is used in off-grid systems to disconnect the PV system from the loads. This helps to ensure that no current can flow back from the inverter to the disconnected circuit, allowing for the safe removal or replacement of components.
This type of solar isolator switch is normally installed next to the inverter or at the load side of the system, in the same AC circuit. It may be a switch to isolate the inverter from the grid, or as switch to electrically separate an electric load or loads with the inverter.
The solar isolator switch, whether DC or AC, is a key component of any solar PV system. It helps ensure safety and provide compliance with local safety regulations while also allowing you to quickly and easily disconnect the system for maintenance or repairs.
When selecting a solar isolator for your system, make sure to choose one that is rated for the voltage and current of your PV system. We hope you now have a better understanding of the different types of solar isolator switches, where to use them, and why.