Moving electricity round our system isn’t just an in-the-moment thing, it requires careful planning and events like Easter require careful consideration.
We’re currently analysing the likely system conditions and options so that as we head into Easter weekend, we can handover a robust plan to our colleagues who are working in the control room.
This includes forecasting demand and how much electricity Britain might want, looking at the predicted weather to think about how much wind and solar might be generated, forecasting the electricity that could go back and forth on interconnectors to the continents whilst also considering all the generation that intends to be online to meet demand.
We bring all this information together to make sure we can keep our system stable and that it has everything it needs to operate, such as the right voltage and inertia requirements, as well as ensuring that second by second supply will match demand.
Our expert planners then advise on the most secure and economic way to configure the transmission network, highlight any outages on the network impacting the plan, confirm which commercial contracts are available to meet our system requirements and any actions our traders could take ahead of time to optimise the system.
It's important we are clear about any uncertainty in our forecasts so we can plan accordingly.
For example, we can’t be sure about the weather days in advance, which in turn impacts on the level of wind and solar generation we expect on the day.
It’s part of our usual processes to continue to refine these forecasts to give our control room the most up to date information the closer we get to real time, but at several days ahead we must still explore various options that need to be available to manage the system so we are ready for anything.
What does demand currently look like from Good Friday to Easter Monday?
Here is our latest forecast for Easter 2020 as of 9 April.
The black line shows national demand, the blue band is estimated embedded wind generation (wind that doesn’t connect directly onto our national transmission system) and the yellow band shows estimated solar generation. The blue line shows “virtual” demand once the three components are added together.
We think Good Friday will be the sunniest day of the Easter break so we anticipate the highest level of solar generation to be throughout Good Friday, reducing as we move towards Easter Sunday.
Historically, demand is usually lowest overnight but this year it looks like daytime minimum demand on Good Friday is lower than overnight minimum demand because of all the renewable generation we are expecting.
The gap between afternoon and overnight minimum level of demand is on Good Friday is almost 1000MW, the equivalent of two conventional power stations. This is incredibly rare - we have only ever observed five other instances where the minimum demand has occurred in the mid-afternoon, rather than overnight.
Easter Monday is anticipated to be the windiest day throughout Easter as shown by the thicker blue volume on the graph as embedded wind generation picks up.
Overall our minimum demand for Easter weekend is expected to be on Easter Monday at 16.8GW – this is only 1GW above our lowest ever observed national demand of 15.8GW.
The hard work our planning teams put in place mean that this is manageable for the ESO control engineers, but it’s very low for this time of year.
How has Covid-19 impacted all this?
It’s certainly reduced demand.
Morning (07:00-13:00) and afternoon (13:00-17:00) continue to be most impacted, with demand reductions of 20% and 18% respectively. The greatest difference continues to be observed between 08:00 and 10:00.
Normally between the overnight minimum and morning peak, demand goes up relatively sharply.
Since the lockdown was introduced the increase of demand during these times has been less steep, likely because many of us are working from home, we aren’t dropping kids off at school and lots of firms and factories have shut down.