In Solar Advice, Solar Panels

Thinking of investing in solar power? Good for you – you’re already on your way to enjoying long-term savings.

The switch is simple, but you might be wondering where to start and more specifically, how many solar panels you might need in Ireland.

In this post, we’ll cover things to consider when shopping for Solar PV (photovoltaic) panels: from energy usage and budget to roof space and orientation to solar panel types and wattage

We’ll help you work out how many Solar PV panels you need based on energy consumption and your budget.

Finally, we’ll lay out the financial support and solar installation services available in Ireland – so you can harness the power of the sunshine, directly into your home.

So let’s get started!

5 Factors to Consider When Shopping Solar

The PV market might seem overwhelming, especially if you’re new to domestic renewable energy sources – so bear the following points in mind when searching for your Solar PV system.

  • Daily Energy Consumption: How much energy you use in your household – and how much you think you’ll need in the future 
  • Potential of Sunlight: Varies depending on your location, and impacts the number of panels you need
  • Your Roof Size: Determines the number of panels, the energy they can produce, and how much they’ll cost
  1. Home Orientation: Your home’s design, and the direction in which it faces, affects how much sunlight it receives – and the number of panels you’ll need
  2. Panel Wattage: Smaller roofs might need more powerful wattage to power the home

1. How Much Energy Do You Use?

To figure out how many PV panels you need in Ireland, check your average daily energy consumption (measured in units of energy called kWh, or total Kilowatt hours). Once you know how much solar energy you need to keep things running smoothly, it’s easier to work out how many solar panels you’ll need.

Psst…Don’t know what your kWh is? Just check your most recent electricity bill. You should be able to see electricity costs for the past month or two, plus the amount you use per year. 

Top Tip: As daily energy consumption levels relate to electrical appliances, if those numbers are high, you might want to consider how many devices you own, how much you use them, and where you could cut back. Can you replace existing appliances with more efficient alternatives? 

By curbing your energy use now, you can work out how much power you’ll need to generate in the future, and how many panels you’ll need to do so.

2. Length of Sunlight Hours: Where and When

Solar PV panels don’t just rely on sunny climates: they work well in cloudy and even cold environments. In fact, Ireland’s cooler climate actually helps the panels work at a high-efficiency level. 

We also get plenty of sunlight – as much as some parts of Germany, one of the big players in solar installations. With all that solar power to play with, PV panels are a great long-term energy choice for Irish homes. 

Still, the amount of sunlight hours varies depending on where your home is and when the measurement is taken. 

After all, some Irish provinces get more hours of sunlight than others – which impacts the amount of electricity that solar panels can generate. According to the below map, for instance, Leinster receives more direct sunlight (with a higher solar potential) than the west; so homes in Connacht might require more panels.

 this map provides a summary of the estimated solar energy available for power generation and other energy applications. It represents the long-term average of daily/yearly totals of direct normal irradiation (DNI). The underlying solar resource database is calculated by the Solargis model from atmospheric and satellite data with 15- or 30-minute time step. The effects of terrain are considered at nominal spatial resolution of 250 m. DNI is the most important parameter for energy yield calculation and performance assessment of concentrating solar power (CSP) and concentrator solar photovoltaic (CPV) technologies. DNI is also important for the calculation of global irradiation received by tilted or sun-tracking photovoltaic modules

© 2020 The World Bank, Source: Global Solar Atlas 2.0, Solar resource data: Solargis. 

So if your area receives more hours of sunlight per year, you won’t need as many panels as households in less sunny climates. Lucky you!

Also, hours of sunlight change throughout the year, typically peaking in May and June when, according to Met Eireann, sunshine duration averages between 5 and 6.5 hours per day over most of the country (in the very southeast, it’s over 7). Although this figure is much lower in winter, don’t worry – your solar panels can still work for you then!

Ireland normally gets between 1100 and 1600 hours of sunshine each year. The sunniest months are May and June. During these months, sunshine duration averages between 5 and 6.5 hours per day over most of the country. The extreme southeast gets most sunshine, averaging over 7 hours a day in early summer. December is the dullest month, with an average daily sunshine ranging from about 1 hour in the north to almost 2 hours in the extreme southeast. Over the year as a whole, most areas get an average of between 3 1/4 and 3 3/4 hours of sunshine each day. 1887 was the sunniest summer in the 100 years from 1881 to 1980, according to measurements made at the Phoenix Park in Dublin.

Your chosen solar PV installation company would typically look at summer consumption levels first and work backwards from there. But if you have your monthly usage to hand, you’ll get even more insights into the best system for your home and area.

3: Do You Have Much Roof Space?

If you’re checking out solar panels for sale in Ireland, take a look at how much roof space you have to work with first. That way, you can assess how many panels you might need. 

For instance, a Caldor Solar 5kW solar system could be made up of 18 solar panels, each with a capacity of 435 watts. Each PV panel is around 1.8 m x 1.15 m in size – so you’d need at least 37m² of roof space for that particular system. 

Psst…Concerned about obstacles like skylights, vents or shade from nearby trees affecting the amount of power you can produce? Don’t worry, our team can provide an assessment to help you choose the most appropriate system for your home’s design. For instance, if you’re tight on space, we may recommend a higher powered system that can pack more punch.

4. Best Orientation For Solar Panels: The Super South

Good news: solar panels in Ireland will generate some electricity regardless of which direction they face. No wasted energy here!

Still, it’s worth mentioning that south-facing solar panels (including southwest-facing and southeast-facing) produce much more power than their northern counterparts.

So if your home faces to the south, you may need fewer panels. Even better if that south-facing roof of yours includes an incline for maximum sun absorption; but remember, surrounding trees and foliage could obstruct all that lovely sunlight. If that’s the case for you, it may be time to get the trimmers out! 

Our team at Caldor Solar can help you manage obstacles like roof shading to help you get the most out of your solar panels, whatever direction they face.

5. Solar Panel Types and Panel Wattage

Now we’ve highlighted the factors affecting the amount of PV panels you need, let’s look at the different types of solar panels available – plus how powerful they can be.

Types of solar panels

  • Monocrystalline: the most efficient option, with a yield of 18–23% – best for homes with limited roof space
  • Thin-film / Amorphous: the cheapest option, although their yield is only 8–12%. They also need a greater number of modules (i.e. more space) to generate the same amount of electricity. 

How many watts do I need?

Found your ideal panel type? Next, consider the panel wattage you’ll need: that’s the amount of electricity generated from a single panel, which is measured in watts (W). FYI, most domestic panels range from 380W to 440W – and at Caldor Solar, our domestic panels have a capacity of 435W.

If you’re not sure what system to pick, take a look at how much energy you consume annually. According to the SEAI, a typical 3 kW solar panel system of around 20m² could generate around 2,600kWh of free electricity per year. That could cover between 40% – 60% of an average Irish household’s energy needs, based on a family-sized home (of 3 – 4 people). 

Of course, if you have a smaller household and consume less power through your appliances, a 2 kW system might suffice.

How many panels do I need? 

Checked your annual power consumption? Picked your system wattage? Now you can calculate how many PV panels you’ll need for your roof. In general, it’s a good idea to fill your roof with panels to maximise your solar potential.

According to the Commission for Regulation of Utilities (CRU), the average home in Ireland uses 4,200 kWh of electricity a year. Based on this figure, if you’re installing a 400 watt solar panel and a 4kW system size, you might need around 10 panels to generate enough energy to meet your household’s needs.

If you want solar to cover around half of your electricity needs rather than the full amount, 6 panels (generating around 2,100 kWh per year) could do the job. However, as energy costs increase, we’d recommend utilising as much roof space with as many panels as possible. After all, the cost of installing panels is not linear – and the more panels you can safely install depending on your roof space, the cheaper each panel becomes.

Note, the above figures will likely vary depending on the other factors we’ve mentioned; not only roof space but your home’s orientation and your energy consumption (which may be much higher if you use air source heat pumps, or if you’re powering an electric car). 

You can assess your household’s energy consumption yourself, by checking your utility bills. For the other factors we’ve mentioned, it’s helpful to consult an expert.

Calculating Panels: Consumption and Cost

To give you an idea of how many panels you might need based on your energy consumption, check out these examples:

My annual consumptionHow many panels I’ll need
Up to 2,000 kWh8+
2,000 – 5,000 kWh5 – 14+
More than 5,000 kWh14+

If you prefer to work out the number of panels based on your budget, you can do that, too. Check out the price ranges below, with their corresponding wattage systems.

House SizeSystem SizeCost (after SEAI grant)Number of Panels
2-bed terraced3.28 kWUp to €6,0007+
3-bed semi-detached4.10 kW€6,000+10+
4-bed detached4.92 kW€6,500+11+

Does the number of panels actually matter?

Sure, it’s useful to know how many panels you might need when considering the switch to solar. It gives you something tangible to work with. 

But it’s not just about how many panels you have; rather it’s about the total power these panels can generate. Because when it comes to solar panel energy, size really does matter! 

So a smaller roof with fewer panels of a higher wattage might generate just as much solar energy as a bigger roof with more panels but a lower system wattage. 

Psst…To see how much energy your choice might generate, you can multiply the number of solar panels you’re thinking about by the power of each panel. If you’re interested in 400 watt panels and are considering 11 panels to fill your roof, that would work out as 400 x 11 or 4,400 watts – which would be more than enough energy for an average Irish home. Note, this is quite a rough estimation and to get a more accurate figure for your home’s location and design, it’s best to reach out to an experienced installation provider.

What Support is Available in Ireland for Solar Panel Installation?

Luckily, you don’t have to make the switch to solar alone: because there’s plenty of support available for homeowners looking to install solar panels in Ireland.

The first kind of support is financial. If you’re worried about the cost of solar panel installation, good news: almost all homeowners (those with houses built before 2021) qualify for an SEAI solar electricity grant.

Most installations can access SEAI grants up to €2,100 – but to apply for one, you’ll need to choose a registered SEAI solar panel installation company in Ireland, like Caldor Solar. 

The second kind of support is practical. Because although the switch to solar can be simple, it’s still a big decision: and you’re likely to need some help with choosing the right Solar PV system, advice on where to place your panels, not to mention someone to carry out the installation process itself.

Fortunately, as well as helping you to get that grant, Caldor Solar can support you with all of these practical elements: getting you set up with the best Solar PV system for your home, for greater daylight and nighttime savings!

Our high-quality and efficient solar panels are designed for various needs and circumstances, and our team can help you choose and install the best ones for your individual household. 

With almost a decade of experience in supplying and installing Solar PV panels, we know what we’re doing – and we’re excited to bring a clean, affordable and simple energy solution into your home.

Final Thoughts: Worked It Out Yet?!

If you’ve been asking: “How many solar panels do I need in Ireland for my home?”, hopefully this post has cleared up any confusion. Remember, choosing a solar panel system – the right size, plus the number of panels – is a big decision that includes a few key factors.

By evaluating your energy usage, location, orientation, plus your ideal panel type and wattage based on your household’s needs (and your budget!), you can then work out how many panels makes sense. 

The right system size will help you to reduce your carbon footprint while lowering your electricity bills – either cutting them in half or maybe even covering all your energy needs through solar, depending on what system you choose and your initial investment.

So. Are you looking for the simplest and smartest way to join Ireland’s solar energy revolution?

Caldor Solar can help you navigate your transition to solar. We’ll make the journey as seamless as possible, and have you up and running in no time!

To get started and work out how many panels you might need to power your home in Ireland, get in touch for a free personalised consultation and quote – or see our services page for more.

Harness The Sunshine; Soak Up The Savings!


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Caldor Solar are solar power pioneers in Ireland, specialising in both residential and commercial solar panels. Check out our testimonials and online reviews to learn more. Or chat with us on 01 253 3349 for a personalised quote for your home. 


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