About the map

Learn more about our offshore wind map.

We manage the seabed out to the 12 nautical mile territorial limit under the auspices of the Crown Estate Act (1961), and it is under the Energy Act (2004) that we have responsibility for renewable electricity generation within the UK Economic Exclusive Zone which extends to the limits of the UK continental shelf.

We have developed an interactive map showing ‘real time’ power generation, the wind speed and direction, and supplementary information as to where offshore generation fits into the national energy mix.

The map, which amalgamates data from various sources (see below for more detail) and updates hourly, shows the estimated total electricity being generated as well as each individual projects’ contribution.

It demonstrates the significant contribution that offshore wind is already making to a low-carbon and secure energy mix.

Where does the data come from?

In order to present as close to real time generation data as is available, the map draws information from several sources as outlined below.

Operational metering

National Grid and offshore wind farm operators monitor generation in real time using meters which measure the instantaneous megawatt (MW) output on the power stations. Typically this data is confidential to the system operator and the wind farm operator. We will publish operational metering data for those wind farms where the operator publishes this information. We will also publish aggregated data reported to the market by National Grid via Elexon, who have responsibility for collecting and publishing market data.

Final physical notifications

Under the market arrangements most offshore wind farm operators publish forecasts of their output. Elexon also publishes this data, known as Final Physical Notifications (FPNs), to the market an hour before the half-hour to which the forecast refers. We use this FPN data as a forecast of output for the wind farms that notify in this format (typically, but not necessarily, with a capacity of greater than 50 MW).


For those wind farms for which FPNs aren't available, an algorithmic approach is used to forecast the output. Calibrated turbine output curves from the manufacturer are used, coupled with expected availability numbers and a publicly available weather forecast (Global Forecast Systems [GFS] at 0.5 degree resolution) from the National Oceanic and Atmospheric Administration in the United States. Forecast accuracy is monitored against settlement metering outputs.

Settlement metering

The company which gathers the data for the UK electricity market is called Elexon; it  publishes half-hourly generation numbers for many of the offshore wind farms from settlement data. This settlement data is published to the market five working days after generation. This data is the most accurate data on the operation of the power stations but obviously not timely enough for understanding what the fleet is producing in any given hour. It should also be noted that not all wind farms are reported by Elexon, as some smaller wind farms are metered in separate arrangements by their host energy suppliers and there is no public visibility on the output of these stations.

What does the data mean?

The power output of a wind turbine fluctuates with wind speed. MW (megawatt) is a measure of the output an offshore wind farm can achieve. MWh (megawatt hour) is the volume of energy supplied. For example, at an average output of 100 MW an offshore wind farm will create 100 MWh of energy in an hour, or 2,400 MWh in a day.

1 MWh = 1,000kWh

1 MWh will meet the electricity needs of an average UK home for around three months

1GWh = 1,000 MWh

1 GWh will light the one million lamps of the Blackpool illuminations for all 66 nights

1 TWh = 1,000 GWh

1 TWh will keep the UK national rail network on the move for over three months

What is the difference between a Watt and a Watt.hour?

A Watt (W) is a measure of POWER, it is the rate at which energy is transferred. 1 Watt = 1 Joule per second. Think of a Joule as a precisely measured quantity of energy. A 2000 W vacuum cleaner therefore consumes energy at a rate of 2000 Joules per second.

As an analogy, imagine opening a tap to fill a bathtub. The water flows at a rate of 10 litres per second. That is the rate at which water is transferred.

A Watt.hour (Wh) is a measure of ENERGY. It is 1 Watt of power flowing for 1 hour. If the vacuum cleaner is used for 2 hours, the quantity of energy used will be 2000 x 2 = 4000 Wh = 4 kWh. Similarly, if the tap with a flow-rate of 10 litres/second is left open for 30 seconds, the quantity of water used will be 10 x 30 = 300 litres.

About the map data

This map and data contained within are for indicative purposes only. No warranties or representations of any kind are given in connection with the map or its content, including the completeness or accuracy of any of its contents.

The Crown Estate, its Commissioners, staff and agents shall not be held liable for any loss or damages or expenses of any kind (direct, indirect or consequential) in connection with use of any information or material contained in or referred to on this map, or otherwise from the use of this map.

You are not permitted to copy, sub-licence, distribute or sell any of this data to third parties in any form.

Unless stated otherwise, all material on this website is the property of The Crown Estate. The material may be used, provided it is reproduced accurately and appropriate acknowledgement is given. You may not sell the information to a third party. By continuing on this website you are agreeing to our Terms of use.

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