Solar System and Standby Generator Configuration

Simple Auto Disconnect

When you have an active solar array installed on an installation with a standby generator, you will need to disconnect your solar when starting the generator. This is easy when you have a manual transfer switch and you need to be on site to start the generator. That way you simply turn off the solar supply, start your generator and you are done.

Now let’s change the way your standby generator is set up.

The generator is set for auto start, you have an automatic transfer switch (ATS) and there is a power failure. Your generator starts immediately and you still have the solar supply active. This makes for a very “unhealthy” generator. You need to find a way to disconnect the solar system when you have a power failure.

The Easy Circuit

The link below will show you a very easy circuit that will de-energise your solar on a power failure automatically and you must then reset the solar manually once normal power is restored. I have opted for the manual reset as the generator and solar are on two different switchboards. You can alter this easily to create a circuit that will “sense” normal power and restore the solar automatically.


Take a look at what will happen.

Once you have wired your circuit, you need to push the “energise” button to energise the contactor. When it is energised, your solar system is connected to the grid. On a power failure, the contactor drops out and remains off until you push the “energise” button again. Pretty simple method using only a push-button and a contactor, but it will save you a lot of headaches.

Make sure you label it clearly that it must only be reset once normal power is restored.

Important Note

Before using this circuit, check with your relevant Authority what their requirements are.