Electricity supply is dictated by demand, which in turn is affected by many factors such as the time of day, the day of the week, holiday periods, air temperatures and other weather conditions.
There is a consistent daily patten in electricity supply, with peak supply in the early evening, reaching a maximum between 5pm and 7pm, and a low point between 3am and 5am on average across the year. The peak periods are similar for all four quarters although Quarter 1 and Quarter 4 show a higher peak. Figure 4.1 shows the average hourly electricity supply by quarter for 2025.
| Quarter 1 | Quarter 2 | Quarter 3 | Quarter 4 | |
| 00:00-01:00 | 4.01 | 3.45 | 3.42 | 3.94 |
| 01:00-02:00 | 3.89 | 3.46 | 3.43 | 3.85 |
| 02:00-03:00 | 3.87 | 3.4 | 3.37 | 3.84 |
| 03:00-04:00 | 3.79 | 3.35 | 3.32 | 3.77 |
| 04:00-05:00 | 3.72 | 3.32 | 3.29 | 3.71 |
| 05:00-06:00 | 3.72 | 3.44 | 3.42 | 3.75 |
| 06:00-07:00 | 3.9 | 3.79 | 3.73 | 3.98 |
| 07:00-08:00 | 4.29 | 4.02 | 3.98 | 4.32 |
| 08:00-09:00 | 4.48 | 4.07 | 4.07 | 4.5 |
| 09:00-10:00 | 4.62 | 4.02 | 4.04 | 4.6 |
| 10:00-11:00 | 4.63 | 3.97 | 4.01 | 4.61 |
| 11:00-12:00 | 4.62 | 3.97 | 4.02 | 4.61 |
| 12:00-13:00 | 4.63 | 3.97 | 4.01 | 4.61 |
| 13:00-14:00 | 4.6 | 3.96 | 3.99 | 4.6 |
| 14:00-15:00 | 4.57 | 3.96 | 3.98 | 4.61 |
| 15:00-16:00 | 4.62 | 3.99 | 4.02 | 4.69 |
| 16:00-17:00 | 4.77 | 4.12 | 4.14 | 4.89 |
| 17:00-18:00 | 4.99 | 4.15 | 4.16 | 5.07 |
| 18:00-19:00 | 5.06 | 4.11 | 4.13 | 5.01 |
| 19:00-20:00 | 4.99 | 4.08 | 4.09 | 4.85 |
| 20:00-21:00 | 4.79 | 4 | 3.96 | 4.63 |
| 21:00-22:00 | 4.52 | 3.79 | 3.74 | 4.35 |
| 22:00-23:00 | 4.2 | 3.59 | 3.58 | 4.09 |
| 23:00-24:00 | 4.11 | 3.53 | 3.5 | 4.03 |
It should be noted that the data shown here is based on UTC (Coordinated Universal Time) and therefore does not account for daylight saving time differences which partially explains the shift between peak supply times for Quarters 1 and 4 compared with Quarters 2 and 3.
The supply of electricity is also dependent on the day of the week with supply highest during mid-week periods and lowest at weekends. Looking at average daily consumption by the day of the week for the whole of 2025, Sundays had the lowest average electricity supply at 91.5 GWh, which was 10% lower than the highest weekday average supply of 101.5 GWh on Thursdays. Mondays have the lowest average mid-week supply due to the impact of bank holidays on the annual average figure.
| Average Daily Electricity Supplied | |
| Monday | 98.56 |
| Tuesday | 100.73 |
| Wednesday | 100.87 |
| Thursday | 101.45 |
| Friday | 100.29 |
| Saturday | 94.56 |
| Sunday | 91.52 |
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