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Ecotricity Explains: The National Grid

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By Adam Ifans
21 May 2024

The National Grid ensures that mainland Britain is supplied with electricity. It’s all around us. In fact, it’s hard to even take a walk without seeing evidence of this incredible network, with cables running to even the remotest locations in the country.

It’s not just about cables, though. The grid is far more complicated than many people realise, so read on to discover everything you need to know about the National Grid.

grid explained
What is the National Grid?

The National Grid is a network of Extra High Voltage and High-Voltage cables which, alongside the Distribution Networks, connects generators and consumers of electricity in Britain. It doesn’t extend to Northern Ireland, which is part of the Irish electricity system. It’s been a privately owned company since 1990.

The National Grid operates at a frequency of 50Hz and has interconnectors to mainland Europe, which means we can export energy when we have a surplus and import when we need more than we generate.

How does our green electricity reach homes and businesses?

The process of powering our homes and businesses is a complex one. Here’s how it works:

Step 1

The first stage of getting power to our homes and businesses is generating the electricity. We do this in our wind and solar farms – some other companies still use climate-wrecking fossil fuel power stations, of course.

Step 2

The electricity is then transformed to three-phase Alternating Current (AC) before being fed into the National Grid, usually at 275 or 400 kilovolts (kV). It’s at this point that the electricity enters the National Transmission Network. The high voltage enables the electricity to be transported more efficiently along power lines supported by steel pylons.

Step 3

The National Grid is divided into 16 transmission zones, each of which is linked to others. While the links are high power lines, this means there can be limited capacity for transmitting electricity from one zone to another. For example, if Scotland’s windfarms are generating huge amounts of electricity on a windy day, there is a limit to how much of that electricity can be transmitted to the wider grid.

Step 4

The National Transmission Network is connected to local Distribution Networks. These are operated by separate companies to the National Grid. Here, the electricity is converted to lower voltages at substations, typically down to 11,33 or 132 kV.

Step 5

The safer, lower voltage electricity can now be distributed through the local network, but the voltage still needs to be reduced before entering our homes and businesses. This is done by hanging transformers that are attached to distribution lines.

Step 6

Electricity is delivered to your home, office or business through what’s called a ‘service wire’ into your premises. It runs into your meter before passing into the rest of the building, so that the amount of electricity you use can be measured.

Is the energy coming into my house actually green?

Effectively, yes. But it’s a little complicated, as we’ll explain.

As you might gather from reading above, the electricity in Britain’s National Grid is all intermingled, regardless of how it was generated. This is because electricity itself (as opposed to its generation) is simply the flow of charge.

However, what’s important is that you’re paying for sustainable electricity, which in turn means that the green stuff is being generated for you and fed into the grid. That’s what matters and that’s how you’re making a difference in the fight against the climate crisis. So the ‘pool’ is still dirty – but you’re making it cleaner.

How are supply and demand balanced?

Keeping the supply and demand of electricity balanced on the National Grid is vitally important. Too little electricity in the grid means people will suffer power shortages, while too much will destabilise the grid, which could stop it working.

Ecotricity is part of the Balancing Mechanism, National Grid’s main tool for keeping Britain’s electricity network balanced.

National Grid has a constantly updating forecast of how much electricity everyone is going to use. Through the Balancing Mechanism, and other frequency response tools, it keeps supply and demand stable by paying electricity generators like Ecotricity to boost or reduce their generation, or activate their batteries, which are perfect in this role due to their super-fast response times. See our blog on our role in the Balancing Market for more info.

How is Ecotricity helping to improve the grid’s infrastructure?

It’s important that energy companies help the National Grid’s infrastructure to use more green energy. We’re doing this in two ways.

Firstly, we’re building our first grid-scale battery storage project at Alveston in Gloucestershire. It has a 10 megawatt 24 MWh capability. Battery storage takes up some space (a 50 megawatt battery would need a site around the size of a quarter of a football pitch) but it’s silent in operation and unobtrusive.

Our battery storage facility will capture and store green energy, so that it can be used to balance the grid when extra electricity is needed. That means there will be less need to fire up fossil fuel reactors to fill in the gaps and green energy will be available 24 hours a day. The more battery storage Britain can build, the better we’ll be able to use the abundant green energy that we have.

You can read more about our grid-scale battery storage plans here.


The second way we’re helping the grid is through our new Ecolibrium platform. It’s a new type of flexible electricity grid that acts like a virtual power plant that we can control to help provide more green energy when needed.

Ecolibrium uses digital technology and complex data processing to control energy demand and output, intelligently balancing them to avoid peaks and troughs - ultimately improving efficiency.

It’s a great way of making the most of the green energy we’re already generating throughout the country, helping every gust of wind and every shard of light make a difference in creating a greener Britain.

You can read more about Equilibrium here.

Ready to start turning your bills into mills?!

Switch to Ecotricity and we’ll use your bill money to build new sources of renewable energy and build a greener Britain.

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