East / West Facing Solar Panel Myth Explored

Alright, let’s talk about rules. Not the big ones, like “don’t juggle chainsaws” or “never trust a dolphin wearing a tie.” I’m talking about the little rules. The ones that get passed down from person to person until they become unquestionable, granite-hard truths.

You know the type. “You have to wait 30 minutes after eating before you can swim or you’ll get a cramp and sink like a particularly dense rock.” For my entire childhood, this was gospel. The 30-Minute Swim Rule was as real as gravity. It was only as an adult that I learned it’s basically a complete fabrication, a myth perpetuated by parents who just wanted 30 minutes of peace to digest their sandwiches.

The world is full of these. And in the world of Irish homeownership, there’s a 30-Minute Swim Rule that has probably cost people thousands of euros. It’s a rule so deeply ingrained that it stops people from even thinking about getting solar panels. It goes like this:

“To get solar panels, you MUST have a perfect, south-facing roof. Anything else is a waste of time and money.”

This rule is usually delivered with the solemn finality of a high court judge. It’s whispered by neighbours over garden fences, stated as fact by well-meaning uncles, and accepted as truth by thousands of homeowners who glance up at their east-or-west-facing roofs and sigh, “Ah well, not for me then.”

For years, this was the conventional wisdom, the unquestionable truth handed down from the ancient Solar Gods. And for years, it was… well, it wasn’t wrong, exactly. It was just based on a game that we’re not playing anymore.

Today, we’re going on a journey. A journey into the heart of solar physics, household electricity usage, and the economics of our bonkers modern energy grid. We’re going to use some data, some logic, and a healthy dose of poorly-drawn stick figures to show you why the Great South-Facing Roof Myth is not only outdated but that for most Irish people, the “compromise” roof is actually the secret weapon for saving money.

It’s time to debunk the biggest myth in Irish solar. It’s time to talk about the unsung hero of renewable energy: the humble, glorious, and economically superior East/West roof.

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Chapter 1: In the Beginning, There Was South

Before we can gleefully tear down the old wisdom, we have to understand where it came from. Why did everyone become so obsessed with south-facing roofs in the first place? It’s not a conspiracy. The logic is actually pretty simple, and it has to do with the sun being a bit lazy.

Imagine your solar panels are tiny, diligent sunbathers. Their job is to lie there and soak up as many rays as possible. The more direct the sunlight, and the longer they’re in it, the better their tan (and the more electricity they produce).

Now, think about where the sun hangs out in the sky here in Ireland. It rises in the east, it makes a low arc across the southern part of the sky, and it sets in the west. It never really pops its head up in the north.

So, if you’re a sunbather and you want the absolute maximum, no-compromises, best-possible tan over the course of a full day, you’re going to face south. You’ll get a bit of sun in the morning, the full, glorious, face-melting blast of it at midday, and a bit more in the afternoon. You are maximizing your total exposure over the entire year.

This is the entire basis for the “South is Best” argument. It’s a strategy designed to do one thing and one thing only: generate the absolute maximum number of kilowatt-hours (kWh) possible over 365 days.

A quick aside on the kWh, because it’s a term we’re going to be throwing around a lot. A kilowatt-hour is a unit of energy. The easiest way to think about it is a “Juice Box.” A standard 4-kilowatt (kW) solar panel system, in one hour of perfect, lab-condition sunshine, can generate 4 Juice Boxes of energy. Your kettle might use one Juice Box to boil. Watching TV for a few hours might use another. A kWh is just a standard-sized Juice Box of electricity. Simple.

So, the south-facing roof was the undisputed champion of making the most Juice Boxes per year. And for a long time, that was the only metric that mattered. Why? Because of how the old solar game was played.

Chapter 2: The Game Has Changed (But the Rulebook Stayed the Same)

Picture this. You’re a baker. You love baking bread. In the Old Days, there was a simple deal. You bake a loaf of bread, and the Big Grid Supermarket buys it from you for €1. Every single loaf. Your goal, as a baker, is simple: bake as many loaves as humanly possible. You build the biggest oven, you work all day, you churn out loaf after loaf after loaf. More loaves = more money. Simple.

This is how the solar industry worked for years. You’d install a system, and under schemes like the Feed-in Tariff, you’d get paid a decent price for every single kWh (every Juice Box) you generated, whether you used it yourself or not. Your south-facing roof was your giant, hyper-efficient oven, churning out the maximum number of Juice Boxes to sell.

But then, the rules changed. Drastically.

Today, the situation is completely different. The Big Grid Supermarket has a new deal for you. If you want to buy a loaf of bread from them, it’ll cost you €3. But if you want to sell them one of your freshly baked loaves, they’ll give you… 20 cents.

Suddenly, your old strategy is a disaster. Churning out hundreds of loaves to sell for a pittance while you’re still buying their expensive bread for your own dinner is a terrible business model. The game is no longer “bake as many loaves as possible.” The new game is: “Avoid the supermarket at all costs by eating your own damn bread.”

This is the modern world of Irish solar. The electricity you buy from the grid is incredibly expensive (your €3 loaf). The money you get for selling your surplus solar power back to the grid—the export tariff—is incredibly small (your 20-cent loaf).

The single most important metric for solar panels in Ireland today is not “Total Generation.” It is “Self-Consumption.”

How much of the electricity you generate can you use yourself, in your own home, to avoid buying it from the grid? That is the question that determines whether your investment pays off. And this, my friends, is where our hero, the south-facing roof, reveals its tragic, fatal flaw.

Chapter 3: The South-Facing Roof’s Big, Lonely Lunch Break

A south-facing solar array has a very distinct personality. It’s a bit of a diva. It wakes up slowly, performs spectacularly for a few hours in the middle of the day, and then clocks off early. Its daily generation profile looks like a big, sharp bell curve.

Let’s be specific. It starts generating a little bit of power around 8 am, ramps up incredibly fast to a massive peak around 1 pm, and then drops off just as quickly, producing very little after 5 or 6 pm in the summer.

Now, let’s think about you. The Human. When do you use electricity? Your daily profile is the complete opposite. It looks more like a two-humped camel.

There’s a “Morning Hump” of activity between 7 am and 9 am. This is when the kettle goes on (multiple times), the toaster is blasting, the electric shower is running, and everyone’s charging their phones before running out the door.

Then, from about 9 am to 4 pm, the house is often empty. Consumption drops to almost nothing—maybe the fridge humming away and a few things on standby. This is the “Midday Trough.”

Then comes the “Evening Hump,” and it’s a big one. From 5 pm onwards, all hell breaks loose. The oven goes on. The hob. The microwave. The dishwasher. The washing machine. The lights come on all over the house. The TV is on. Laptops are plugged in. You’re using a ton of electricity, and you keep using it until you go to bed.

Now, let’s overlay the two graphs. The south-facing solar production curve and the typical Irish household consumption curve.

It’s a catastrophe. A total mismatch.

The south-facing system is throwing an epic, raging party of free electricity right in the middle of the day… when nobody is home. All that beautiful, valuable power—peaking right in the Midday Trough—has nowhere to go. So, what happens? It gets exported to the grid for pennies. You’re selling your delicious homemade bread for 20 cents a loaf.

Then, in the evening, just as your family comes home and your house starts demanding electricity like a hungry monster, your south-facing diva has already packed up and gone home. And you’re forced to buy expensive grid electricity all evening. You’re buying the supermarket’s €3 loaf.

This is the fundamental problem. A south-facing system is optimised for a world that no longer exists. It’s a sprinter in a marathon world. It generates the most power, but it generates it at the worst possible time.

If only there were a different way. A way to generate power that actually matches the rhythm of our lives…

Chapter 4: Enter the Underdog: The Two-Shouldered Giant

Okay, so the south-facing roof is a flawed hero. Now let’s meet our new protagonist: the East/West roof.

This setup is exactly what it sounds like. Instead of putting all your panels on one side of the roof facing south, you split them. You put half facing east, and half facing west.

At first glance, this feels like a terrible compromise. Neither set of panels is ever pointing at the “best” spot. The east panels get the morning sun but miss the afternoon. The west panels miss the morning but get the evening. Surely this is worse?

But let’s look at the generation curve. It’s completely different. It doesn’t have the single, sharp peak of the south-facer. Instead, it has a beautiful, broad, M-shaped curve. Some people call it a “two-humped” or “shouldered” profile.

Here’s what happens:

• The Morning Shoulder: The east-facing panels wake up early. As soon as the sun rises, they start churning out power, creating a strong peak of generation right when you’re in your “Morning Hump” of consumption. They’re making power for your kettle and your shower, in real-time.
• The Midday Dip: Around noon, when the sun is high overhead, neither set of panels has a perfect angle. Production dips down. But who cares? You’re not home anyway! This is the Midday Trough.
• The Evening Shoulder: As the sun moves into the afternoon and evening, the west-facing panels take over. They keep generating significant power long after the south-facing system has given up for the day. This production shoulder lines up perfectly with your “Evening Hump.” The west panels are helping to run your oven, your dishwasher, and your TV, for free.

Now, let’s do that overlay again. Let’s put the M-shaped East/West generation curve on top of our human consumption curve.

It’s… perfect. It’s a beautiful, symbiotic relationship. The solar panels are making power exactly when you need to use it. You are eating your own bread for breakfast and for dinner. You are maximising your self-consumption. You are winning the new game.

Chapter 5: The Nerdy Numbers Bit (I Promise It’s Worth It)

“Okay,” I hear you say, “that all sounds lovely in theory. But what about the raw numbers? Surely it still makes less power overall?”

Yes. Yes, it does. And this is the bit that everyone gets hung up on. But let’s look at how much less. To figure this out, we don’t need to guess. We can use an incredibly powerful and, frankly, quite brilliant tool from the European Commission called the Photovoltaic Geographical Information System, or PVGIS. It’s basically a supercomputer that has swallowed decades of weather data and can simulate with terrifying accuracy how much electricity a specific solar panel system will generate in a specific location.

I ran the numbers for a standard 4kW system in three Irish cities: Dublin, Cork, and Galway. I compared a “perfect” south-facing roof with an East/West split. Here’s what the big brain computer spat out:

Look at that. It’s incredibly consistent. Across the country, the East/West system produces about 13% less total electricity over the year.

And this is the number that scares people. A 13% loss! Disaster! But it’s not. It’s a 13% trade-off for getting your power at the right time. Remember, every Juice Box you use yourself is worth 15 times more than one you sell to the grid. The East/West system might make 13% fewer Juice Boxes, but a much, much higher percentage of them are the super-valuable “self-consumed” kind. The result? A faster payback period and a better return on your investment.

But wait, there’s more! The East/West system has a couple of other nerdy superpowers.

Superpower #1: Dodging the “Clip”

Your solar system has a component called an inverter. Its job is to convert the DC electricity from your panels into the AC electricity your house uses. Think of it as a funnel. Now, in Ireland, for a standard single-phase connection, that funnel can only handle a flow of 3.68kW at any one time. On a cool, sunny summer’s day, a 4kW south-facing system can easily try to generate more than that. When it does, the inverter says “Nope, too much!” and it “clips” the production, effectively throwing away any energy generated above that 3.68kW limit. You’re pouring a fire hose into a kitchen funnel.

The East/West system almost never has this problem. Because only half the system is in peak sun at any one time, the total power rarely gets near the 3.68kW limit. It’s like pouring two garden hoses through the funnel, one after the other. No spillage. This means on the very best days for solar, the usable energy from an E/W system is much closer to a south-facing one than the annual averages suggest.

Superpower #2: Making Batteries Better

A home battery is essentially a lunchbox for your solar energy. You use it to store the cheap power you generate at midday to use during the expensive evening peak. A south-facing system makes a giant, awkward lunch all at once that you have to cram into the biggest lunchbox you can find. The west-facing panels of an E/W system, however, keep generating power directly into the evening, meaning you don’t need to pull as much from your battery. This means you can often get away with a smaller, cheaper battery, or that the battery you do have will last longer because it’s not being worked as hard every day. It’s a win-win.

Chapter 6: Your House is a Leaky Bucket

Okay, we’ve established that for generating and using electricity, an East/West roof is a secret weapon. But this whole conversation is part of a much bigger picture. The goal isn’t just to generate more useful energy; it’s to need less energy in the first place.

Most Irish homes are leaky buckets. Or maybe a better analogy is a sieve. We pour expensive, hard-won energy (whether from the grid or our solar panels) into our homes, and it just leaks right out through uninsulated walls, drafty windows, and paper-thin attics.

Getting solar panels without addressing your home’s insulation is like installing a world-class, audiophile sound system in a convertible with the top down, driving through a hurricane. You’re just creating beautiful energy and letting it vanish into the wind.

Before you even think about the optimal angle for your solar panels, or how big a battery you need, you should think about plugging the leaks. This is the hierarchy of making your home an energy-efficient spaceship.

First, you put a hat on it. That’s attic insulation. It’s often the cheapest, easiest, and most effective upgrade you can make, stopping a huge amount of heat from escaping upwards.

Then, you give it a big, cozy coat. For many homes, the gold standard for this is external wall insulation Dublin. This involves wrapping the entire outside of your house in a thick layer of insulation. It’s a bigger job, but it fundamentally transforms your home’s ability to retain heat, slashing your overall energy demand for years to come. It reduces the size of the energy bucket you need to fill every day.

Once you’ve stopped your house from leaking energy like a sieve, then you can perfect your energy generation strategy with solar panels. It’s all part of a single, holistic project of turning your home into a comfortable, efficient, and cheap-to-run machine. If you’re considering any of these upgrades, from insulation to solar, a great first step is to look into a full home energy retrofit.

Thinking about the whole system is key. For a deeper dive into what’s involved with solar specifically, the folks at Retrofit Dublin have a great guide on Solar Panels in Dublin that’s worth a read.

Conclusion: The New “Best”

So, we’ve been on quite a journey. We started with the ancient, unquestioned wisdom of the South-Facing Solar Gods. We saw that their logic was sound, but based on a game that no longer exists. We uncovered the tragic flaw of the south-facing system—its terrible timing—and we met the unsung hero, the East/West roof, with its beautiful, life-synchronised generation curve.

The data is clear. An East/West system in Ireland will generate about 13% less raw energy per year. But it will generate that energy at times that are vastly more valuable to you, the homeowner. It will empower you to use your own free, clean electricity and avoid buying expensive grid power. It will, for the vast majority of working families, deliver a better financial return.

The “best” solar roof is no longer the one that points in a specific cardinal direction. The best solar roof is the one that’s designed around the rhythm of your life. And for a huge number of Irish homes—especially the classic “gable to gable” houses that naturally face east and west—the roof you thought was a compromise might just be the smartest choice you can make.

So next time you hear someone solemnly declare the “South-Facing Only” rule, you can smile, nod, and know that the game has changed. The underdog won. And if you’re ready to see how this new strategy could work for your home, it might be time to get a proper assessment for Solar Panels in Dublin.