EirGrid and SONI issued their Winter Outlook for 2020-21 on 15 October in which they warned that if high generator forced outage rates continue over the winter period there is a risk of System Alerts.
The transmission system operators (TSOs) said the all-island capacity margin this winter is predicted to be 929MW (see Figure 1), with this margin having reduced every year over the past five years. This is mainly due to increasing demand, dispatchable generation exiting the market and increasing generator forced outage rates. They said that, despite the expected margin, if high forced outage rates continue over the winter, there is a risk of System Alerts, particularly when renewable generation is at a low output and support is not available from GB across the interconnectors. In NI, if the forced outage of just one large generator over the winter period coincides with low renewable generation there is a risk of a System Alert. The margin is predicted to be at its tightest at the end of November and start of December.