Main grid transmission reliability rate excellent in 2025

The main grid transmission reliability rate indicates the amount of energy transmitted for consumption in the main grid in relation to the total energy available for transmission.

Key figures for the main grid in 2025. The averages for the preceding five years are given in parentheses.

• The transmission reliability rate in the main grid was 99,99995 % (99,99985 %). 
• The volume of electrical energy not transmitted for consumption because of disturbances was 35 MWh (111 MWh).
• The number of electricity supply interruptions (≥ 30 seconds) caused by disturbances was 0.10 per connection point (0.11).
• Disturbances caused an average 2.2 minutes (2.8 minutes) interruptions at connection points.
• The volume of energy not received from power plants was 77 MWh (286 MWh).
• The System Minute (SM) was 0.16 min (0.46 min).
• The Average Interruption Time (AIT) was 0.24 min (0.79 min).
• The imputed economic detriment (KAH) that disturbance interruptions caused to consumer customers was lowest so far, EUR 1.4 million (2.6 million). KAH is calculated according to the Finnish Energy Authority's monitoring method.

The quality of frequency in the Nordic synchronous area was at an excellent level and improved significantly last year. In 2025, the frequency was outside the normal range (49.9–50.1 Hz) for approximately 5,100 minutes. The upper limit set by the European network code is 15,000 minutes and the Nordic target is 10,000 minutes.

Several electricity market development projects were introduced, such as the 15-minute day-ahead and intraday markets and the 15-minute mFRR energy market. The implemented market changes are estimated to have had a positive impact on the recent development of frequency quality. New reserve technologies, such as the widespread use of electricity storage, are also estimated to have had a positive impact on frequency quality.

Further information is available on our website under Supply security of electricity - Fingrid

The website also provides annual fault statistics for the Nordic and Baltic AC grid and fault and availability information for the cross-border DC connections.

Further information:

Markku Piironen, Specialist, Fingrid Oyj,
Our e-mail addresses are firstname.lastname@fingrid.fi