I think people do not realize that there is a huge bonus for the first country to unlock the "negative price energy peak" achievement.
There are some businesses that will only be possible in these conditions and they will flock to the first country with it. Generating hydrogen seems like the most straightforward one, but there are also bio-ethanol processes that require some energy to be profitable.
We see intermittency as a curse, but I think we overestimate the difficulty to adapt to an intermittent schedule and we underestimate the advantage of having time spans with free energy, especially when they happen during the day.
Yes, right now we don't see this effect because the obvious thing to do is to sell it to your neighbor so they can temporarily shut down coal or gas plants. That effect will kick in when your neighbors can't do that anymore (e.g. because they also switched to the same type of intermittent power) and there won't be any easy way to cash out on additional electricity. We are not there yet.
What was unusual was the fact that it surpassed the demand on Ireland’s electricity grid throughout the entire island for the first time.
That meant that some of the energy was exported to Britain and Ireland had to meet the rest of the demand using fossil fuels.
That confused me in this summary. Looking at the actual article makes sense of that nonsense:
Currently, the country’s electricity grid is only permitted to have a maximum of 75 per cent renewables in its energy mix. That meant that some of the energy was exported to Britain and Ireland had to meet the rest of the demand using fossil fuels.