What happens when solar or wind energy production suddenly drops? How does an electrical grid react when it loses more than half of its supply in a matter of seconds? These questions are no longer hypothetical: several recent events have shown that The intermittency of renewable energy can test the stability of national electricity systems., especially if adequate prevention, management and adaptation measures are not taken.
The energy transition to less polluting sources is not only urgent, but also inevitable. However, as seen in Spain, Chile, Australia, and other countries with high renewable penetration, this shift implies complex technical challengesThe key is not to stop the advance of renewables, but to understand their particularities and ensure that the electricity grid is ready to integrate them without compromising its operation.
What is energy intermittency and why does it affect the electrical system?
Intermittency in power generation It refers to the non-programmable variability of some renewable sources, such as solar photovoltaic or wind power. Unlike thermal or nuclear power plants, which can adjust their production based on demand, these technologies depend on external factors such as the sun or wind.
This variable nature causes mismatches between electricity generation and consumption. If there is not enough storage or backup, an imbalance is generated that causes fluctuations in frequency and voltage, potentially triggering crises such as blackouts or massive disconnections.
For example, during the blackout of April 28, 2025 in Spain, the grid frequency dropped dramatically from 50 Hz to 49 Hz in five seconds, causing the automatic shutdown of a large part of the electrical systemAt that time, more than 70% of generation came from intermittent renewable energy.
Structural factors that intensify the effects of renewable intermittency
The truth is that The traditional electricity grid was not designed to operate with high renewable penetrationThere are several factors that further complicate the situation:
- Networks with obsolete infrastructure: Many transmission lines are not adapted to transport large volumes from remote areas, where solar or wind farms are located, to urban centers.
- Low storage: Without sufficient batteries to absorb excess production during the day and release it at night, the grid experiences abrupt peaks and valleys.
- Decentralization not accompanied by digitalization: A decentralized network requires intelligent management and control systems to know in real time what each node is generating or consuming.
- Integration difficulties: The connection of new renewable plants is often slowed down by bureaucracy or a lack of available grid capacity.
All of this exponentially increases the possibility of instability., especially in scenarios where renewable generation reaches 80% to 100%—as occurred in Spain weeks before the blackout.
The Spanish case: renewable intermittence and the historic blackout of 2025
April 28, 2025, became a turning point. At midday, with the grid supplied by 82% clean sources, a failure in solar generation in the southwest of the Iberian Peninsula triggered a chain reaction that the entire Iberian Peninsula network collapsed, including Portugal, Andorra and parts of southern France.
15 GW of energy disappeared in just five secondsNuclear power plants were shut down for safety reasons. The grid was isolated from France and without external support. The system, lacking backup and with low inertia (the absence of large synchronous rotations like those offered by hydroelectric or thermal turbines), failed to stabilize.
This event put on the table a series of technical, political and structural problems which reflect the risks of a poorly planned energy transition:
- Insufficient inertia in the system: Non-synchronous renewables (such as solar PV) do not contribute rotational force to the system, making disturbance containment difficult.
- Lack of reagents and controllable power: Without immediate mechanisms to compensate for rapid changes, the frequency drops to unsafe levels.
- Underinvestment in interconnections: Spain has a poor connection with France (3–5% of installed capacity), well below the 10% recommended by the EU.
- Absence of isolation protocols: The affected area could not be disconnected to prevent cascading failure.
What consequences does this have for the economy and society?
The 2025 blackout exposed the vulnerability of an increasingly electrified societyAccording to the CEOE, the economic losses amounted to 1.600 billion euros, almost 0,1% of Spanish GDP in half a day. Even more worrying was that seven people died during the incident due to the interruption of critical electrical services such as hospitals.
Furthermore, the event raised doubts about the grid's reliability, affecting the perception of energy security and slowing international investment. In a context of accelerated electrification—electric vehicles, induction cookers, heat pumps— Having an unstable network can be catastrophic.
Lessons from other countries: Australia, Chile and Latin America
Spain is not the only country facing these challenges. In South AustraliaA large-scale blackout was linked to the massive disconnection of wind farms during a storm, due to the lack of response of inverters to low-voltage events.
En Chile, solar overproduction in the north of the country has saturated transmission lines to the south, forcing the disconnection of up to 25% of the generated energy and generating negative prices in the wholesale market. Without storage, this energy is lost.
Countries like Mexico, Argentina o Colombia They face similar problems: insufficient transmission infrastructure, interconnection restrictions, bottlenecks in areas with high solar or wind capacity, and bureaucratic difficulties for new connections.
Storage: the key to stabilizing the grid
One of the fundamental pillars to mitigate the effects of intermittency is the energy storage. Batteries allow to absorb the surplus of renewable energy and release it when demand requires it, smoothing out power peaks and reducing dependence on thermal power plants. For more details, visit our section on energy storage systems.
In solar farms, for example, Installing batteries can prevent economic losses due to unplanned outages, and also allows energy to be sold at times of higher prices, stabilizing the system and benefiting the entire electricity market.
The Chilean government has already begun incentivizing large-scale battery projects as part of its strategy to prevent solar waste. Spain has also announced pilot programs, but deployment is still slow compared to the exponential pace of new photovoltaic installations.
Better investors, more protection: Technology also needs to advance
Modern solar and wind plants are connected to the grid using inverters that They transform direct current into alternating currentHowever, many current inverters are not prepared for extreme situations: when power drops, they automatically disconnect, exacerbating the imbalance.
The solution is to develop and implement smart investors, capable of:
- Actively participate in stabilization (e.g., injecting reactive power).
- Withstand voltage or frequency drops without immediately leaving the grid.
- Synchronize with other elements of the system (such as a "virtual synchronous generator").
This type of technology would allow renewables themselves not only not to be a problem in critical moments, but contribute to solving them.
Digitalization of the system and active demand management
One of the common mistakes is to think that we should only act on production. electricity demand can also be made more flexibleServices such as active demand response allow large industrial consumers to temporarily disconnect when there is a risk of collapse, in exchange for financial compensation. For more information, visit our guide on renewable energies and artificial intelligence.
This approach, if expanded and digitalized, could include thousands of residential and commercial consumers. For example, electric car chargers or heat pumps can slow down their consumption for minutes without affecting their operation, but it does provide enormous stability to the system.
Furthermore, the digitalization of the network, with IoT sensors, real-time monitoring, artificial intelligence, and predictive maintenance systems, allows failures to be detected and prevented before they occur, improving efficiency and reducing the risk of blackouts.
Can a stable electricity grid be 100% renewable?
Many experts agree that It is technically feasible to have a 100% renewable electricity mix, but provided that complementary measures are adopted, such as:
- Decentralize production, bringing generation points closer to consumption areas.
- Vary the sources: not focusing only on solar or wind, but including hydropower, bioenergy, and storage.
- Invest in international interconnections: being able to import and export energy stabilizes flows.
- Planning the network according to intelligent and data-driven nodes.
Some voices, however, suggest that at least for the next decade it will be necessary maintain some backup capacity with combined gas cycles, which can start quickly when extreme conditions require it.
Others advocate exploring new forms of dispatchable energy, such as geothermal or even reopen the debate on nuclear energy as a low-emission complement.
Whatever the approach, what is clear is that Network security cannot be mortgaged to ideologyDecisions must be based on data, technology, and engineering.
With the energy transition underway, the growth of renewable sources is unstoppable. However, The intermittency inherent in technologies such as solar or wind power remains a technical threat that must be treated seriously.Events like the 2025 blackout in Spain have shown that it's not enough to generate clean energy in large quantities; we must do so in a controlled, predictable, and stable manner.
Modernizing the grid, investing in storage, implementing smart inverters, decentralizing production, and digitalizing the system are essential steps if we want a clean future for electricity. y Sure. It's not about choosing between renewables or stability, but rather integrating both through planning, investment, innovation, and long-term vision.
