That is the article CC quoted. I like this bit:

Carbon Commentary · Spain's variable wind and stable electricity networks

As its electricity transmission company, Red Eléctrica de España or REE, reminds us, the country is unusually isolated from international interconnections. It is `a peninsula electrically speaking, with weak electrical interconnections with the European Union'.[1] A country with limited capacity to import or export power has more issues accommodating large amounts of wind power. Denmark has international connections to cover 50% of its electricity while Spain has less than a tenth this amount. (The UK also scores extremely poorly on this dimension.)

Spain is able to manage the integration of wind power into its grid primarily because it has reasonable amounts of hydro-electricity and pumped storage.[2] Hydro-electricity can be used when winds are less than expected and pumped storage can assist both when wind is unexpectedly high or unexpectedly low.

And also

But is wind so variable that power stations need to provide immediate backup? The utterly superb REE website provides easy-to-use data to test this theory. I've used this data to try to demonstrate that wind production was remarkably consistent during the peak day of 8 November.[3] Not only is wind speed largely predictable with good meteorology, but REE data shows that even in the windy days of early November, the amount of electricity generated only varied gradually.

Woo hoo! A "superb" data source for making charts... My mouth is watering already...

En un viejo país ineficiente, algo así como España entre dos guerras civiles, poseer una casa y poca hacienda y memoria ninguna. -- Gil de Biedma