Wider generation TNUOS forecasts

BESS sites that are transmission connected or of capacity >=100MW face wider generation TNUoS charges.

These are flat rates that a site must pay each year.

We use the ESO Wider Generation TNUoS forecasts to inform our projections

The Electricity System Operator has produced Wider Generation TNUoS forecasts for 2024-2029 and for 2029-2033.

These are shown in the figure above for several of the 27 generation regions; in the dotted lines.

The NESO numbers are high in the late 2020s

The final 5 years of the NESO forecast suggest ~£20k/MW revenue for battery sites across much of Great Britain around 2030. We think this is an unintended outcome; particularly for sites in Scotland where TNUoS is expected to represent a cost rather than a revenue. TNUoS is expected to represent a location-specific mechanism that does not incentivize new build generation in Scotland (as there is already a lot of generation and not much demand).

The significant revenues for battery sites in these NESO projections are due to how these forecasts have been generated.

• The Wider Generation TNUoS calculation depends on a national 'Adjustment' tariff. This dominates for batteries as they have a small Annual Load Factor (which dampens the Year Round elements). The adjustment tariff has been set using a European regulation, and we're not sure about its validity now GB is no longer in the EU.

The Modo view is in the solid line above, shown to 2050. We use the NESO numbers to 2028. Beyond that, we take a flat line. We assume an Annual Load Factor (ALF) which is the stated new build BESS number of 1.2391%

Wider generation TNUoS carries a significant policy risk, due to the Review of Electricity Market Arrangements (REMA). Any outcome of REMA is set for around 2030.

Wider Generation TNUoS in the Modo Forecast

You can see the impact of the wider generation TNUoS rates via Custom Runs.