Battery duration has risen from 1.4 hours to 3.4
Neither NESO nor Litgrid publishes duration anywhere in a connection register. The capacity market does, because the de-rating class states it explicitly, and the trend is unambiguous.
Weighted by connection capacity, mean duration runs from 1.40 hours for 2023 delivery to 3.41 hours for 2028/29. The market has moved from frequency response assets to energy shifting assets inside five years, and the register does not record it at all.
What it changes
Duration decides which revenue a battery can earn. A one hour asset lives on frequency products; a four hour asset can trade the daily spread and cover an evening peak. A queue position that was designed around a one hour asset is a different commercial proposition from the same position built out at four hours, and nothing in the connection register distinguishes them.
The tool joins the capacity market record to the map so a connection point can be read alongside what has actually been built nearby, and at what duration.