7 mins read
Across the sun-scorched plains of Extremadura and the windswept hills of Galicia, a quiet revolution has turned into a roaring success. Spain has become a global superpower in renewable energy. In 2025, the country is shattering records, with green sources like solar and wind frequently generating over half of the nation's entire electricity supply.
This incredible achievement has cut emissions, reduced reliance on fossil fuels, and positioned Spain at the forefront of the fight against climate change. But this success has created a deeply ironic problem: Spain is now producing so much cheap, clean energy that its national Spanish electricity grid cannot handle it.
This is the green energy paradox. On the sunniest days, state-of-the-art solar farms are being ordered to shut down, deliberately wasting perfect, free energy. This guide explores why this is happening, the consequences of this "curtailment," and the multi-billion-euro race to build an energy system for the future.
Spain's achievement in green energy is monumental. Thanks to its abundant sunshine and wind, coupled with decades of investment, the country has fundamentally decarbonized its power production.
The statistics for 2025 are staggering. On many days, solar power in Spain, combined with wind, has accounted for over 60% of national electricity demand. This has provided a crucial buffer against volatile gas prices and created a thriving domestic industry. In almost every respect, Spain has won the first battle of the energy transition: generating vast quantities of clean power.
The problem isn't with the energy generation, but with its transmission. The national grid, managed by Red Eléctrica de España (REE), is the network of "energy highways" that transports power, and it's facing a massive traffic jam.
Green energy is harvested in rural, sunny, or windy regions (like Extremadura and Castile and León), while the highest demand comes from industrial centers and cities like Madrid and Barcelona. The grid, designed for an older model of a few large, centralized power plants, lacks sufficient "highway lanes" to transport this huge volume of energy over long distances.
When the grid becomes congested, the operator (REE) must prevent it from overloading. It does this by ordering power plants to reduce or stop their production. This is known as renewable energy curtailment. It's the absurd situation of a solar farm being forced to switch off on a brilliantly sunny day because there's simply nowhere for the clean electricity to go. This means a significant amount of potential clean energy is wasted each year.
This bottleneck has serious economic and environmental ripple effects.
At midday on a sunny weekend, when industrial demand is low and solar production is at its peak, the grid becomes flooded with a massive energy surplus. This causes wholesale electricity prices to plummet to zero or even go negative, meaning producers have to pay to offload their power. While this can mean cheap bills for some consumers, it creates market chaos and discourages future investment in renewables.
The most frustrating consequence is that while a solar farm in the south is being curtailed, a gas-fired power plant in the north might need to be switched on to meet local demand because the clean energy couldn't get there. This undermines the primary goal of the green transition.
The Spanish government and REE are tackling this "high-quality problem" with an ambitious, multi-faceted strategy.
The National Integrated Energy and Climate Plan (PNIEC) outlines a massive, multi-billion-euro investment to upgrade the Spanish electricity grid. This includes building new high-voltage power lines to connect production and consumption hubs and implementing smart technologies to optimize power flow.
Large-scale battery storage in Spain is a game-changer. These giant battery parks can absorb the cheap, excess solar power generated at midday and store it. In the evening, when the sun sets and demand peaks, they can release this clean energy back into the grid, ensuring solar power is available 24/7 and stabilizing prices.
Excess renewable energy can be used to power electrolyzers, which split water to create green hydrogen. This converts electricity that can't be transported into a clean, storable fuel. This green hydrogen can then be used to power heavy industry or transport, effectively turning the grid congestion problem into a new green export opportunity.
Spain's energy transition is a key part of its future. Learn more about another crucial issue in our Guide to Spain's 2025 Water Crisis.
Q1: Is my electricity bill cheaper because of all the renewable energy?
A1: It can be. If you are on a variable or dynamic electricity tariff, your bill can be significantly lower, especially during sunny midday hours when prices can drop to zero. However, the overall cost of electricity also includes grid fees, taxes, and other charges.
Q2: What is "renewable energy curtailment"?
A2: Curtailment is the deliberate reduction of energy output from a generator (like a solar or wind farm) by the grid operator, usually because the grid cannot handle the amount of power being produced and risks overloading.
Q3: Why doesn't Spain just build more power lines?
A3: It is! But building major new high-voltage power lines is a massive infrastructure project that is extremely expensive and takes many years to plan, get permits for, and construct. The current grid upgrade is one of the largest infrastructure projects in the country.
Q4: How does battery storage help the grid?
A4: Battery storage acts like a buffer. It absorbs excess electricity when there is too much supply (like on a sunny afternoon) and releases it when there is high demand (like in the evening). This smooths out the peaks and troughs of renewable generation, making the grid more stable and efficient.
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