Why Ireland is Throwing Away Truckloads of Free Sunshine (And How We Can Stop)

Let’s say you decide to get healthy. You’re all in. You buy the fancy running shoes, the weirdly tight clothes, the smartwatch that judges your every move. You start getting up at 5 AM to run, you eat kale until you’re pretty sure you’re turning green, and you become one of those people who talks about their VO2 max at parties.

You are, by all accounts, crushing it. You’re a health superstar.

Now imagine that one day, your body’s personal trainer—let’s call him Barry—shows up mid-run, taps you on the shoulder, and says, “Alright champ, that’s enough health for today. I need you to stop running and go eat three donuts. For stability.”

You’d be confused. You’d be annoyed. You’d probably eat the donuts, but you’d have a lot of questions. This, in a nutshell, is what’s happening to solar power in Ireland right now.

Ireland has been absolutely smashing its renewable energy goals. We’ve been installing solar panels and wind turbines like they’re going out of style, becoming a genuine world leader in the race to clean energy. We are the health superstar of the energy world. But a strange thing has started happening. On beautiful, sunny, breezy days—the perfect days for making clean power—our national grid operator, a very serious entity called EirGrid, has to effectively tap our solar farms on the shoulder and say, “Alright lads, that’s enough sunshine for today. Power it down.”

This isn’t a rare thing. In the first six months of 2025, Ireland was forced to waste—or “curtail,” to use the official jargon—a mind-boggling 88.7 gigawatt-hours of perfectly good solar power.

What’s a gigawatt-hour? Don’t worry about it. Just know that the total amount of clean wind and solar energy we threw away in that six-month period was enough to power every single home in County Dublin for the entire same period. We’re generating free, clean energy from the sky and then… just leaving it there. It’s like ordering a pizza and then, when it arrives, telling the delivery guy to just keep it.

So what on Earth is going on? Are we insane? Is the grid haunted? Is this some bizarre fossil fuel conspiracy?

The truth is a lot weirder, a lot more interesting, and involves the physics of spinning things, traffic jams on invisible electricity highways, and why our national power grid is basically a finicky, high-strung, 100-year-old man who is deeply suspicious of new things like “the sun.”

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Part 1: The Grid is a Jenga Tower Built on a Wobbling Plate

Most of us think of the electricity grid as a big bucket. Power plants pour electricity in, and we scoop it out to run our Netflix and air fryers. Simple.

This is, unfortunately, completely wrong. The grid is not a bucket. It’s not a lake or a battery. The grid is a ridiculously complex, real-time balancing act that makes a tightrope walker juggling chainsaws look like a nap.

The single most important rule of any power grid is this:

Power being put IN must exactly equal power being taken OUT. At every single second of every single day.

If for even a moment, more power is generated than is being used, the whole system’s frequency—which in Europe is supposed to be a rock-solid 50 Hz—starts to rise. If more power is used than is generated, the frequency falls. If it deviates by even a tiny amount, things start to break. If it deviates by a lot, the whole system collapses in a cascading failure we call a “blackout.”

So, the job of EirGrid is to be the ultimate party host, constantly running around making sure that for every person who starts using a new appliance (taking a drink), a power plant somewhere ramps up to make that exact amount of new power (pours a new drink). It’s an impossible, thankless job.

For a century, this was hard, but manageable. That’s because all our power came from one type of source: the Old Guard.

The Old Guard vs. The New Kids

Imagine the grid is a giant, heavy, spinning merry-go-round. To keep it stable, you need a lot of weight.

The Old Guard (Fossil Fuels, Hydro): These are our traditional power plants. They work by burning something (gas, coal) to boil water, create steam, and spin a massive, multi-ton metal turbine. These turbines are the giant, heavy things that give the grid its stability. They are physically, mechanically synchronized to the grid’s 50 Hz frequency. Their sheer rotating mass creates a property called inertia.

Inertia is just a fancy word for “resistance to change.” A freight train has a lot of inertia. A housefly does not. Because these old power plants have so much physical inertia, they act like giant shock absorbers for the grid. If a power line suddenly goes down, the immense spinning weight of all these turbines keeps the grid’s frequency from crashing instantly, giving the grid operators precious seconds to react. They are the big, heavy adults on the merry-go-round, keeping it spinning at a steady, safe speed.

The New Kids (Wind and Solar): These are our renewable heroes. But they work differently. They don’t have giant, heavy, spinning turbines connected directly to the grid. Instead, they generate direct current (DC) power and use a clever piece of electronics called an inverter to convert it into alternating current (AC) that the grid can use. They are “non-synchronous.”

This makes them incredibly efficient and fast, but they have a key difference: they have virtually zero inertia. They don’t add any physical, spinning weight to the system. They’re like a bunch of incredibly athletic kids who can jump on and off the merry-go-round instantly to give it a push, but they don’t add any stabilizing weight.

And this is where our problem begins. We’re adding more and more athletic kids (solar and wind) and retiring the big, heavy adults (fossil fuel plants). The merry-go-round is becoming lighter, faster, and much, much wobblier.

To prevent the whole thing from flying apart, EirGrid had to create a rule. It’s called the System Non-Synchronous Penetration (SNSP) limit. It’s basically a bouncer at the door of the grid club, saying, “Okay, we can only have a certain percentage of these new-fangled, no-inertia generators on the system at any one time.”

Through some truly world-class engineering, Ireland has pushed that limit to 75%—one of the highest in the world. It’s a massive achievement. But it’s still a hard ceiling. When the combined power from wind and solar threatens to exceed 75% of the country’s total electricity demand, the bouncer has to step in and tell someone to stop generating. This is one of the big reasons for our wasted energy problem.

Part 2: The Two Types of Wasted Energy: The Traffic Jam and The Full Car Park

When EirGrid tells a solar farm to power down, it’s not just for one reason. The industry uses the umbrella term “dispatch-down,” but it’s made of two very different problems that require two very different solutions. To understand this, let’s switch analogies from a merry-go-round to a road network.

Imagine Ireland’s electricity grid is a series of towns (where we use power) connected by roads (power lines). The power plants are breweries, making delicious energy beer.

Problem #1: Constraint (The Local Traffic Jam)

Let’s say there’s a fantastic new craft brewery in a small village in the west of Ireland. It’s a sunny day, and they are brewing up a storm. But the only way out of the village is a tiny, one-lane country road. Soon, there’s a massive traffic jam of beer trucks trying to leave the village. The main motorways of the country have plenty of space, but the beer is stuck behind a local bottleneck.

The grid operator sees this and calls up that specific brewery. “Sorry lads, you have to stop brewing. Your local road can’t handle the traffic.”

This is a constraint. It’s a location-specific problem caused by a physical bottleneck in the local grid. The only way to solve it is to upgrade that specific road. This is the overwhelming reason for wasted renewable energy in Northern Ireland, where the grid in certain areas just isn’t strong enough to get the power out.

Problem #2: Curtailment (The Entire Country’s Car Park is Full)

Now imagine a different scenario. It’s a sunny, windy Bank Holiday weekend. Demand for electricity is low because everyone is at the beach. All the renewable breweries across the entire country are producing at full tilt. There are no local traffic jams—the roads are fine. The problem is bigger: there’s simply more beer being produced everywhere than the entire country can possibly drink.

The grid operator looks at the whole system and realizes it’s about to be flooded with unwanted energy beer. So, it gets on the loudspeaker and announces, “Attention all renewable breweries! Everyone needs to cut production by 10% right now. The whole system can’t handle it.”

This is curtailment. It’s a system-wide problem, not a local one. It happens when the total amount of renewable energy being generated is more than the grid can safely handle, usually because of those inertia and frequency stability issues we talked about earlier.

And this—curtailment—is the primary villain in the story of wasted solar power in the Republic of Ireland. Our problem isn’t so much local traffic jams; it’s that on sunny days, the whole national car park gets full.

Part 3: The Great Midday Mismatch

So why does the car park get full, specifically for solar?

It comes down to a fundamental clash of personalities between the sun and humanity.

The sun is a creature of habit. It gets up, gets really bright and powerful around noon, and then goes to bed. Its power output looks like a big, simple arch.

Humans are… more complicated. We get up and turn on the kettle and the toaster, causing a morning spike in electricity demand. Then many of us go to work, and demand dips during the day. Then we all come home around 6 PM, crank up the oven, turn on the TV, charge our devices, and create a massive evening peak in demand. Our daily demand profile is famously known as the “duck curve,” because it looks vaguely like a duck.

Here’s the problem: solar is producing the most power right in the middle of the day, during the duck’s belly, when our demand is often not at its highest. This creates a massive surplus of energy right when we don’t need it.

This is then made ten times worse by the inertia problem. Remember how the grid needs those big, heavy, spinning fossil fuel plants to stay stable? EirGrid has a rule called the “Minimum Number of Units On” (MUON), which mandates that a certain number of these old-guard plants must be running at all times, purely for stability.

So picture this: It’s 1 PM on a sunny Sunday in May. Demand is low. The solar farms are absolutely screaming with power—enough to meet the entire country’s needs. But the MUON rule says that, say, four big gas plants have to stay online to provide inertia. To make room for these gas plants that must run for stability, EirGrid has no choice but to call up a perfectly good solar farm and tell it to shut down. The clean, free energy from the sun gets curtailed to make way for a fossil fuel plant that’s only running to act as a paperweight.

It feels insane, but from a grid physics perspective, it’s a necessary evil to prevent a blackout. And when you look at the newly released data from EirGrid, this is exactly what’s happening. The main reason for solar curtailment isn’t the 75% SNSP ceiling being hit; it’s overwhelmingly due to “high frequency issues and minimum generation operational constraints”. It’s the midday mismatch and the inertia imperative working together to throw away our sunshine.

Part 4: The Multi-Billion Euro Plan to Fix It

Okay, so the situation seems pretty bleak. Our grid is an old man who’s scared of change, and we’re throwing away clean energy. Are we doomed to this fate forever?

Thankfully, no. EirGrid isn’t just sitting around shrugging. They have a massive, ambitious, multi-billion-euro master plan called “Shaping Our Electricity Future” (SOEF). It’s essentially a plan to give the grid a full-body transplant, a brain upgrade, and send it to therapy to deal with its commitment issues with renewables.

The plan has three main pillars.

Pillar 1: Build Bigger Roads (Grid Reinforcement)

This part is straightforward. To solve the “constraint” problem (the local traffic jams), we need to build bigger roads. The SOEF roadmap includes a portfolio of over 350 projects to reinforce the grid, building new high-voltage lines, upgrading old ones, and installing new substations. It’s a colossal undertaking, like upgrading all the B-roads in the country to motorways. This will primarily help get wind power out of the windy bits of the country and solar power out of the sunny bits, future-proofing the network for even more renewables.

Pillar 2: Get Some Giant Buckets (Flexibility and Storage)

Bigger roads are great, but they don’t solve the main “curtailment” problem—having too much energy at the wrong time of day. For that, you need buckets. Big ones.

This is the flexibility part of the plan, and it’s where things get really cool.

Giant Batteries (BESS): The most obvious solution is to install massive batteries. These Battery Energy Storage Systems (BESS) are the key to solving the midday mismatch. They can act like giant sponges, soaking up all that excess solar power at 1 PM when nobody wants it, and then wringing it all back out at 7 PM when everyone is trying to cook a frozen pizza. Ireland is already deploying hundreds of megawatts of this kind of storage, with plans for much more.

Hosepipes to Our Neighbours (Interconnectors): Another way to deal with a surplus is to sell it. Interconnectors are giant undersea cables that connect our grid to our neighbours. We already have ones to Great Britain, and the new Celtic Interconnector will link us directly to France. This is a game-changer. When we’re overflowing with solar and wind power, we can just pump it over to France and get paid for it, turning a waste problem into a revenue stream.

Pillar 3: Teach the Old Man New Tricks (Smarter Operations)

This is the brain upgrade. It involves changing the very rules by which the grid is operated.

Pushing the Limits: The plan is to safely and progressively increase the SNSP limit from its current 75% all the way up to 95% by 2030. This is a world-first, bleeding-edge goal that requires huge innovation in how the grid is monitored and controlled.

Firing the Bouncers: As new technologies like batteries and things called “synchronous condensers” come online that can provide stability without generating power, EirGrid can further reduce the MUON requirement—the number of fossil fuel plants that have to stay on for inertia. Every time that number drops, it frees up more room on the grid for renewables.

Electricity Happy Hour (Demand-Side Response): This might be the cleverest part. Instead of just trying to make supply match our rigid demand, what if we could make our demand match the supply? This is called “demand-side response.” It means creating incentives (like cheaper electricity tariffs) for people and businesses to use more power when it’s abundant and clean—i.e., in the middle of a sunny day. Your smart washing machine could automatically run at 2 PM, your electric car could be set to charge only when the sun is shining, and large factories could shift their heavy processes to midday. It’s about turning electricity demand from a rigid problem into a flexible solution.

Part 5: What This Means For You, A Regular Human

This all sounds very grand and technical, but it has real-world consequences for all of us. Wasting huge amounts of clean energy is a problem because it makes the whole green transition more expensive and less efficient. It hurts the financial case for building new solar farms, which could slow down our progress towards our climate targets.

And while EirGrid’s grand plan is fantastic, you might be wondering if there’s anything you can do besides waiting for a giant battery to be built down the road.

The answer is a resounding yes. And it starts not with generation, but with reduction.

The single most powerful thing you can do to help the grid, reduce your bills, and fight climate change is to simply use less energy. Before you even think about getting a home battery to store your solar power, you should first ask: is my house an energy sieve?

Trying to power a poorly insulated home with renewables is like trying to fill a leaky bucket. You can keep pouring more and more water in (solar panels, batteries), but you’re fighting a losing battle. The smarter first step is to just patch the holes.

This is where things like attic insulation and external wall insulation Dublin come in. They are the unglamorous, unsung heroes of the energy transition. A well-insulated home is like a giant, slow-release thermal battery. In winter, it holds onto the heat you generate for far longer, so your heating system runs less. In summer, it keeps the heat out. This drastically reduces your home’s overall energy demand, which in turn reduces the strain on the grid at those critical peak times. It’s often the most cost-effective investment you can make in your home’s energy performance, and it’s a foundational step for any serious home energy upgrade.

If you’re looking to understand what’s involved, there are some excellent resources out there, like this guide to home energy grants that can help you start the journey. By reducing your own demand, you’re helping to flatten that “duck curve” and making it easier for the grid to accommodate more renewables. You’re patching your own bucket, which helps the whole system.

The Sunny Horizon

So, yes, Ireland is throwing away sunshine. But it’s not out of madness or incompetence. It’s a predictable—if frustrating—growing pain of a country that’s moving faster on its green journey than its legacy infrastructure can keep up with. It’s a symptom of success.

The problem of curtailment is a sign that we’ve moved into the next, more complex chapter of the energy transition. The challenge is no longer just about building more solar panels and wind turbines; it’s about building a fundamentally smarter, more flexible, and more robust grid to support them.

The good news is that the plan to do exactly that is in motion. It’s a colossal task, involving thousands of people, billions of euros, and a whole lot of copper wire. But it’s happening.

The grid of the future will be less like a fragile, wobbling plate and more like a dynamic, intelligent ecosystem—one that can store the sun’s energy in batteries, share it with our neighbours through interconnectors, and cleverly manage demand to meet the supply. And in the meantime, the best thing we can do is patch our own leaky buckets, making our homes as efficient as possible while the engineers work on building a grid that’s finally ready for the sunshine. If you’re ready to take the first step on that journey, you can start by exploring options for installing Solar Panels in Dublin.