The National Commission for Markets and Competition (CNMC) has formalised a package of emergency measures to stabilise the voltage of the mainland electricity system. The document introduced temporary modifications to operating procedures, with an initial validity of 30 days, extendable up to three months.
The adjustment followed weeks of rapid voltage variations which, although within safety margins, threatened the system’s stability. To address this, Red Eléctrica de España (REE) requested an increase in synchronous power injection—from combined-cycle, hydro or nuclear plants—and a restriction on the instantaneous participation of intermittent renewable sources.
In practice, since October the Spanish electricity system has been operating with a lower share of renewable energy and a greater weight of conventional technologies, resulting in additional curtailments and higher costs.
When the operator limits renewable generation after the day-ahead market has cleared, that displaced energy is remunerated under the technical restrictions mechanism, with prices higher than the pool.
Solar PV is the most affected because its generation depends on an instantaneous, non-controllable resource that responds directly to solar radiation at any given time. This technology also tends to operate with very narrow flexibility margins and high concentration in specific areas, exacerbating local voltage fluctuations.
By contrast, wind power has a more stable and gradual generation curve, which allows easier adaptation to new ramps and reduces mechanical stress on turbines.
More synchronous power, less renewable energy
According to Juan Virgilio Marques, CEO of the Spanish Wind Energy Association (AEE), the current scenario responds to a technical emergency logic but generates economic and operational distortions.
“Wind is not the technology that will be most seriously affected by this change, nor the one that needs to introduce the most modifications to its control systems, because it already operates with similar ramps and a more gradual behaviour,” he told Strategic Energy Europe. However, the industry’s concern lies in the lack of information and a defined timeline: “We don’t know how long the reinforced operation will remain in place or what criteria will determine its end. The sector’s attitude is constructive and we are willing to cooperate, but we demand clear technical and temporal limits.”
Since 1 October, the Spanish electricity market has been operating with clearings every 15 minutes, replacing the hourly model. Added to this change is REE’s instruction imposing minimum 15-minute ramps for all technologies, much stricter than the typical two-minute ramps in the day-ahead market.
These ramps smooth voltage fluctuations by avoiding abrupt changes in power injection, but they also limit the flexibility of solar PV plants, which operate with instantaneous resources and tend to follow real-time market prices.
Wind farms face no difficulty with these ramps; their behaviour is naturally gradual. The PV sector, however, suffers the most because of its instant response and need to capture peak prices. Now they must anticipate or delay generation, leading to penalised imbalances.
Unfair penalties and unavoidable deviations
The operator maintains imbalance penalties even when deviations stem directly from the new operating rules. If a plant ramps up fifteen minutes early to meet the ramp requirement or continues injecting energy during ramp-down, it incurs a deviation beyond its control.
According to Marques, this scheme must be reviewed because it penalises behaviours resulting from regulatory obligations.
The adjustment creates a double effect: curtailed energy that cannot be injected due to renewable displacement, and energy injected outside the scheduled programme due to compliance demands. Both factors reduce market profitability and increase operational complexity.
The Official State Gazette (BOE) itself acknowledges that these measures are exceptional and temporary, yet the CNMC leaves the door open to successive extensions and a potential structural review of Operating Procedure 7.4, which will govern dynamic voltage control for renewables.
However, this process could take up to twelve months, requiring reprogramming, testing, and electronic adaptations. In the meantime, reinforced operation will remain in force until further notice.
