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Data as of 2026-09-20
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Built 2026-09-21 (21 September 2026)

Slovakia Demand Forecast Accuracy: Error, Bias and Worst Miss, 23 August to 20 September 2026

The day-ahead demand forecast for Slovakia was off by 2.1% on average (mean absolute percentage error) over 687 hours from 23 August to 20 September 2026, and 92% of hours landed within 5% of the reading. Its bias was +0.5%: it ran high on average, an over forecast. The largest miss was 298 MW (9.6%) too low at 1 Sept 2026, 20:00 CEST (UTC+02:00). Dates and times are local (Europe/Bratislava).

Key Facts

  • The day-ahead demand forecast for Slovakia was off by 2.1% on average (mean absolute percentage error) over 687 hours from 23 August to 20 September 2026, and 92% of hours landed within 5% of the reading. Its bias was +0.5%: it ran high on average, an over forecast. The largest miss was 298 MW (9.6%) too low at 1 Sept 2026, 20:00 CEST (UTC+02:00).
  • Across 47 European bidding zones ranked by average error over their own latest 30 day windows, Slovakia came 9 (1 is the smallest error).
  • On average the forecast differed from reported demand by 58 MW, against average demand of 2,712 MW.
  • The forecast was above reported demand in 55% of compared hours.

Forecast Error at a Glance

687 hours from 23 August to 20 September 2026
Average error2.1%
Bias+0.5%
Hours within 5%92%
Worst miss298 MW

Average error is the mean absolute percentage gap between the forecast and reported demand. Bias is the signed mean (+13 MW per hour on average): the forecast ran high on average, an over forecast. The worst miss was 298 MW (9.6%) too low at 1 Sept 2026, 20:00 CEST (UTC+02:00): forecast 2,810 MW, reported 3,108 MW.

Source: ENTSO-E Transparency Platform (transparency.entsoe.eu), CC BY 4.0. Aggregated and converted by World Power Monitor; ENTSO-E does not endorse this site. (ENTSO-E Terms of Use plus CC BY 4.0 for listed data items) Data as of 2026-09-20. Accuracy is computed by World Power Monitor from the operator's hourly forecast and reported demand.

Forecast and Reported Demand, Last 7 Days

Local time, to 20 Sept 2026, 14:00 CEST (UTC+02:00)
Slovakia day-ahead demand forecast and reported demand by hour Hourly reported demand and the day-ahead forecast for Slovakia over the last 7 days of the window, to 20 Sept 2026, 14:00 CEST (UTC+02:00). Gaps are hours with a missing, zero or implausible report. 0 1,000 2,000 3,000 4,000 13 Sept, 15:0014 Sept, 15:0015 Sept, 15:0016 Sept, 15:0017 Sept, 15:0018 Sept, 15:0019 Sept, 15:00
Hourly reported demand and the day-ahead forecast for Slovakia over the last 7 days of the window, to 20 Sept 2026, 14:00 CEST (UTC+02:00). Gaps are hours with a missing, zero or implausible report.
Data to 2026-09-20
Slovakia day-ahead demand forecast and reported demand by hour
Local hourReported demandDay-ahead forecast
13 Sept, 15:002,431 MW2,330 MW
13 Sept, 16:002,481 MW2,427 MW
13 Sept, 17:002,565 MW2,526 MW
13 Sept, 18:002,641 MW2,586 MW
13 Sept, 19:002,757 MW2,628 MW
13 Sept, 20:002,686 MW2,626 MW
13 Sept, 21:002,548 MW2,482 MW
13 Sept, 22:002,425 MW2,374 MW
13 Sept, 23:002,293 MW2,240 MW
14 Sept, 00:002,199 MW2,263 MW
14 Sept, 01:002,132 MW2,205 MW
14 Sept, 02:002,137 MW2,168 MW
14 Sept, 03:002,157 MW2,192 MW
14 Sept, 04:002,206 MW2,258 MW
14 Sept, 05:002,390 MW2,403 MW
14 Sept, 06:002,785 MW2,784 MW
14 Sept, 07:002,965 MW2,988 MW
14 Sept, 08:003,071 MW3,125 MW
14 Sept, 09:003,142 MW3,243 MW
14 Sept, 10:003,049 MW3,232 MW
14 Sept, 11:003,035 MW3,266 MW
14 Sept, 12:003,015 MW3,234 MW
14 Sept, 13:002,996 MW3,171 MW
14 Sept, 14:002,949 MW3,083 MW
14 Sept, 15:002,973 MW3,035 MW
14 Sept, 16:002,984 MW3,011 MW
14 Sept, 17:002,983 MW2,992 MW
14 Sept, 18:002,931 MW3,018 MW
14 Sept, 19:002,980 MW3,130 MW
14 Sept, 20:002,953 MW3,044 MW
14 Sept, 21:002,781 MW2,849 MW
14 Sept, 22:002,612 MW2,652 MW
14 Sept, 23:002,526 MW2,534 MW
15 Sept, 00:002,407 MW2,375 MW
15 Sept, 01:002,322 MW2,278 MW
15 Sept, 02:002,294 MW2,233 MW
15 Sept, 03:002,297 MW2,230 MW
15 Sept, 04:002,346 MW2,293 MW
15 Sept, 05:002,416 MW2,425 MW
15 Sept, 06:002,578 MW2,723 MW
15 Sept, 07:002,632 MW2,863 MW
15 Sept, 08:002,679 MW2,900 MW
15 Sept, 09:002,700 MW2,895 MW
15 Sept, 10:002,632 MW2,843 MW
15 Sept, 11:002,668 MW2,868 MW
15 Sept, 12:002,691 MW2,933 MW
15 Sept, 13:002,635 MW2,915 MW
15 Sept, 14:002,527 MW2,818 MW
15 Sept, 15:002,537 MW2,788 MW
15 Sept, 16:002,609 MW2,840 MW
15 Sept, 17:002,716 MW2,933 MW
15 Sept, 18:002,805 MW2,960 MW
15 Sept, 19:002,905 MW2,998 MW
15 Sept, 20:002,881 MW2,980 MW
15 Sept, 21:002,685 MW2,805 MW
15 Sept, 22:002,530 MW2,603 MW
15 Sept, 23:002,400 MW2,455 MW
16 Sept, 00:002,313 MW2,404 MW
16 Sept, 01:002,242 MW2,304 MW
16 Sept, 02:002,192 MW2,253 MW
16 Sept, 03:002,226 MW2,258 MW
16 Sept, 04:002,291 MW2,332 MW
16 Sept, 05:002,454 MW2,506 MW
16 Sept, 06:002,779 MW2,787 MW
16 Sept, 07:002,938 MW2,935 MW
16 Sept, 08:002,966 MW2,970 MW
16 Sept, 09:002,939 MW2,934 MW
16 Sept, 10:002,853 MW2,878 MW
16 Sept, 11:002,843 MW2,883 MW
16 Sept, 12:002,846 MW2,953 MW
16 Sept, 13:002,828 MW2,951 MW
16 Sept, 14:002,817 MW2,855 MW
16 Sept, 15:002,836 MW2,823 MW
16 Sept, 16:002,914 MW2,903 MW
16 Sept, 17:003,012 MW2,974 MW
16 Sept, 18:003,026 MW3,015 MW
16 Sept, 19:003,130 MW3,056 MW
16 Sept, 20:003,083 MW3,041 MW
16 Sept, 21:002,855 MW2,873 MW
16 Sept, 22:002,661 MW2,655 MW
16 Sept, 23:002,552 MW2,493 MW
17 Sept, 00:002,460 MW2,534 MW
17 Sept, 01:002,400 MW2,434 MW
17 Sept, 02:002,358 MW2,377 MW
17 Sept, 03:002,341 MW2,387 MW
17 Sept, 04:002,405 MW2,453 MW
17 Sept, 05:002,562 MW2,615 MW
17 Sept, 06:002,894 MW2,889 MW
17 Sept, 07:003,086 MW3,107 MW
17 Sept, 08:003,212 MW3,207 MW
17 Sept, 09:003,254 MW3,213 MW
17 Sept, 10:003,180 MW3,246 MW
17 Sept, 11:003,204 MW3,261 MW
17 Sept, 12:003,157 MW3,237 MW
17 Sept, 13:003,160 MW3,174 MW
17 Sept, 14:003,076 MW3,052 MW
17 Sept, 15:003,029 MW3,006 MW
17 Sept, 16:003,046 MW3,005 MW
17 Sept, 17:003,080 MW3,044 MW
17 Sept, 18:003,067 MW3,044 MW
17 Sept, 19:003,131 MW3,065 MW
17 Sept, 20:003,105 MW3,086 MW
17 Sept, 21:002,927 MW2,897 MW
17 Sept, 22:002,737 MW2,686 MW
17 Sept, 23:002,638 MW2,556 MW
18 Sept, 00:002,496 MW2,465 MW
18 Sept, 01:002,412 MW2,364 MW
18 Sept, 02:002,335 MW2,310 MW
18 Sept, 03:002,348 MW2,332 MW
18 Sept, 04:002,422 MW2,383 MW
18 Sept, 05:002,538 MW2,531 MW
18 Sept, 06:002,920 MW2,861 MW
18 Sept, 07:003,093 MW3,002 MW
18 Sept, 08:003,127 MW3,069 MW
18 Sept, 09:003,078 MW3,051 MW
18 Sept, 10:002,945 MW2,984 MW
18 Sept, 11:002,933 MW2,975 MW
18 Sept, 12:002,970 MW3,023 MW
18 Sept, 13:002,903 MW2,982 MW
18 Sept, 14:002,794 MW2,930 MW
18 Sept, 15:002,786 MW2,922 MW
18 Sept, 16:002,889 MW2,960 MW
18 Sept, 17:002,946 MW2,980 MW
18 Sept, 18:002,992 MW2,962 MW
18 Sept, 19:003,046 MW2,996 MW
18 Sept, 20:002,997 MW2,965 MW
18 Sept, 21:002,834 MW2,779 MW
18 Sept, 22:002,664 MW2,599 MW
18 Sept, 23:002,502 MW2,477 MW
19 Sept, 00:002,391 MW2,390 MW
19 Sept, 01:002,298 MW2,295 MW
19 Sept, 02:002,263 MW2,242 MW
19 Sept, 03:002,250 MW2,210 MW
19 Sept, 04:002,279 MW2,237 MW
19 Sept, 05:002,304 MW2,245 MW
19 Sept, 06:002,355 MW2,303 MW
19 Sept, 07:002,463 MW2,419 MW
19 Sept, 08:002,561 MW2,542 MW
19 Sept, 09:002,599 MW2,637 MW
19 Sept, 10:002,582 MW2,647 MW
19 Sept, 11:002,585 MW2,674 MW
19 Sept, 12:002,558 MW2,674 MW
19 Sept, 13:002,531 MW2,630 MW
19 Sept, 14:002,480 MW2,554 MW
19 Sept, 15:002,423 MW2,513 MW
19 Sept, 16:002,488 MW2,545 MW
19 Sept, 17:002,581 MW2,582 MW
19 Sept, 18:002,631 MW2,566 MW
19 Sept, 19:002,748 MW2,638 MW
19 Sept, 20:002,670 MW2,643 MW
19 Sept, 21:002,537 MW2,539 MW
19 Sept, 22:002,429 MW2,405 MW
19 Sept, 23:002,314 MW2,285 MW
20 Sept, 00:002,217 MW2,281 MW
20 Sept, 01:002,120 MW2,186 MW
20 Sept, 02:002,084 MW2,151 MW
20 Sept, 03:002,069 MW2,128 MW
20 Sept, 04:002,077 MW2,151 MW
20 Sept, 05:002,113 MW2,169 MW
20 Sept, 06:002,183 MW2,227 MW
20 Sept, 07:002,282 MW2,331 MW
20 Sept, 08:002,406 MW2,455 MW
20 Sept, 09:002,529 MW2,554 MW
20 Sept, 10:002,576 MW2,588 MW
20 Sept, 11:002,581 MW2,601 MW
20 Sept, 12:002,501 MW2,539 MW
20 Sept, 13:002,436 MW2,489 MW
20 Sept, 14:002,370 MW2,447 MW

Assumptions

  • Only hours with both a forecast and a positive demand reading count (687 of 687 hours in the window). Missing and zero values, and readings under 30% or over 3 times the grid's own median for the window, are treated as reporting faults and left out.
  • Error is (forecast minus reported demand) divided by reported demand; average error uses absolute values so high and low misses do not cancel. Bias keeps the sign and does cancel.
  • Reported demand is preliminary and may be revised. A 30 day window is a short sample and one heat wave or holiday can move these figures.
  • European figures are for the ENTSO-E bidding zone named on this page. US and European grids are ranked separately.