Last September, the Spanish electricity system operator, Red Eléctrica, recorded "sudden voltage fluctuations" in the electricity grid and asked the National Commission on Markets and Competition (CNMC) to approve a series of regulatory changes to strengthen the electricity system in the face of the possibility that these problems could impact the security of supply. However, Red Eléctrica assured that the anomalies recorded in September did not imply a risk of a massive power outage like the one on April 28, a statement echoed by the Association of Electric Power Companies (Aelec), the employers' association that brings together Iberdrola, Endesa, and EDP.

The electricity companies' association Aelec, which includes Iberdrola, Endesa and EDP Spain, pointed this Monday to "poor management" by Red Eléctrica as the main cause of the massive blackout on April 28. A report by the association, prepared by Inesc Tec and Compass Lexecon with data from its members – who represent 45% of the installed capacity and 78% of the distribution networks – warns of "poor programming of conventional generation", such as nuclear, combined cycle gas, coal and large hydroelectric plants.