When we first moved in and were on builder’s electricity (supplied by a diesel generator via makeshift cables) the voltage used to fluctuate all the time and we had frequent power cuts.
Once we moved onto mains electricity supplied by underground cables things did improve for awhile. We still got random power cuts, sometimes just for a second or so and other times much longer and the voltage fluctuated at times causing the lights to dim. It was and still is frustrating but then some have dismissed this because it is Spain and the rapid increase in housing during the boom years apparently overloaded the supply.
However, I have noticed that since we have been back from the UK the lights have not been dimming as they did before we left. Checking on my UPS, the voltage has not fluctuated very much and is now staying high at near 250 volts. Before we left, the voltage would drop to 230 and less which is why the lights dimmed and the microwave slowed down.
Has Iberdrola done something to the supply whilst we were away, or is this just a fluke?