Inertia, frequency, voltage, thermal, constraints…these are just a few of the factors that go into the highly complex process of balancing the grid. 

But don’t worry if you’re not up to speed on the detail – balancing the grid is a highly complex activity – and we aim to provide the basics in this section of Electricity Explained. 

The role of the ESO is to ensure electricity supply meets demand second by second, which is what we mean by ‘balancing’ the grid.  

And when you think about how demand rises and falls throughout the day, how it is affected by weather and seasons and then about supply too, how that’s unpredictable and can change at a moment’s notice, it’s clear we need a lot of tools at our disposal.  

Electricity is transported to all corners of Great Britain. And properties like voltage and frequency must be carefully regulated across the whole network to ensure power generated at scale in industrial power stations can be safely used by domestic appliances plugged into wall sockets. 

We see to it this happens smoothly and efficiently, working with industry partners to provide ‘ancillary services’ that keep our electricity supply reliable, affordable and safe.  

National Grid ESO - control room engineer COP image

What are system notices?

Everything you need to know about the different types of system notices and why we issue them.

National Grid ESO - RIIO 2 project progress tracker - Car driving on country road between fields

What are margins?

Our role as Britain’s electricity system operator is to manage the flow of electricity around the grid so it’s available when people need it – and that means keeping the supply secure.

Sunrise over fields

What is inertia?

A simple definition of inertia is that it’s an object’s tendency to continue in its existing state of rest or motion.

ESO - Man child laptop

What are constraints payments?

It’s our job to keep the cost of running the system as low as possible, so we can keep energy bills down. One of the ways we do this is with constraint payments.