The 'sell electricity to Ireland' bit here is doing an awful lot of work. It's more complicated than that.
For those who don't know, Ireland operates an all-island grid, and EirGrid (the grid operator for the Republic) owns SONI (the grid operator for Northern Ireland). That means that 'UK' and 'Ireland' in this has a large Northern Ireland shaped lump of ambiguity that statement.
It shouldn't be that complicated. The UK sells electricity to Ireland (and vice-versa?) in the same way that Belgium, France, the Netherlands, Denmark and Norway sell electricity to the UK, and vice-versa.
Don't tell me EirGrid's EWIC that comes onshore at Dublin and Greenlink at County Wexford are an "NI-shaped lump". They are sources of electricity for the whole island, when it's needed, just like the UK's interconnects with the continent.
https://en.wikipedia.org/wiki/List_of_high-voltage_transmiss...