Solar Panel Sizes & Dimensions UK (Do they even matter?)

According to the Microgeneration Certification Scheme (MCS), by the end of 2023, the UK had over 1.5 million solar installations nationwide.

It's clear that households are taking a greater interest in renewable technology like solar, primarily due to it being cheaper than it was a decade ago. 

Additional factors include climate change and the current energy crisis emphasising the need for increased energy independence. 

However, when it comes to purchasing a solar array, it’s important to understand sizes for optimal energy generation. 

Not sizing your solar array correctly can, on the one hand, result in spending more than you should. Alternatively, you may end up with a solar system that is too small to meet your goals. 

This article provides a comprehensive guide to solar panel sizes in the UK, exploring their significance and considerations for residential and commercial applications.

PS If you are considering a new solar installation, we factor in the size of the system to meet your goals as standard - get your fixed price quote here. 

Let’s dive in!

Solar Panel Sizes Key Points:

• Domestic solar panels come with an average power output of 250-400 watts.

• In terms of dimensions, domestic solar panels average 1.7 metres long, and 1 metre wide and have a thickness of 3cm to 5cm.

• Domestic solar panels can weigh between 18kg - 20kg on average. 

• Considering wattage, weight and dimensions is key to designing the system that meets your goals.

• High energy efficiency is often a sign of a high-quality solar panel and manufacturer.

• All of these factors are considered during the solar array survey process.

Solar Panel Sizes: Understanding the Basics

So, what exactly does solar panel size mean?

This guide will primarily focus on solar panel sizes in terms of wattage (power output).

However, solar panel size can also refer to their physical dimensions, as well as their weight.

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Solar Panel Power Output: 

Wattage is a measure of how much electricity a solar panel generates per hour.

The average domestic solar system tends to offer between 3kW and 5kW of power in total and is composed of approximately six to twelve panels altogether.

This is because systems are generally sized to meet the average energy consumption of UK households (around 2900kwh a year – according to Ofgem).

Some property types are also limited to the physical number of panels that can fit on a roof, certainly when it comes to trying to avoid north-facing elevations. 

Solar Panel Physical Dimensions: 

Alternatively, solar panel size can refer to the panel's physical dimensions.

You’ll want to ensure the panels fit snugly on your roof and look the part as much as possible.

Therefore, consider solar panel dimensions to get an idea of the overall scale of a proposed solar system.

In terms of dimensions, domestic solar panels average 1.7 metres long, and 1 metre wide and have a thickness of 3cm to 5cm.

Solar Panel Weight:

Lastly, solar panel size may refer to the weight of each solar panel and it’s essential that your roof can bear the weight of your desired system. 

Otherwise, you risk damage occurring to your roof. Roof damage can prove very dangerous, but at the least, highly expensive.

The good news is that a complete survey is part of the solar quote process, during which your roof's health and structural status will be assessed. 

On average, domestic solar panels can weigh between 18kg and 20kg. 

Explore a Solar Case Study: Check out an insightful Q&A session featured in one of our detailed case studies on domestic solar panels. Hear directly from a Heatable customer in the UK and gain valuable perspectives on their experience here.

The image above shows a 23-panel solar installation, carried out by the MCS-certified solar team at Heatable, featuring the REA Fusion2 solar panels.

How to Calculate the Number of Solar Panels You Need

Now you know the average sizes, you may be asking how to determine how many solar panels you'll require. 

In order to calculate the number of solar panels you need to power your home, your MCS-accredited installer will take the following steps: 

1. Establish the electrical rating of the PV array in kilowatts peak (kWp). 

2. Determine the postcode region.

3. Determine the array pitch.

4. Determine the array orientation.

5. Lookup kWh/kWp (kK) from the appropriate location-specific table.

6. Determine the shading factor (SF) using the shade factor procedure.

However, it's certainly worth being aware of the general calculation used to determine your solar array requirements: 

Step 1: Determine your annual energy use 

The first step is to verify how much energy you use each year. 

You can do this by checking last year's energy bill and making sure you didn’t buy an EV that could mess up your numbers. 

For reference, according to Ofgem, the average electricity bill for a household of 2-3 is around 2,900kWh a year. 

You can then divide this amount by 365 e.g. 2,900/365 = 7.94 kWh a day, although one study conducted by Statista revealed that consumers can consume as much as 35% more electricity in the winter months than compared to the summer months.

This is due to shorter daylight hours and spending more time indoors during these periods.

Installing a battery with your solar system can help flatten this curve by taking advantage of off-peak charging tariffs. Read our comprehensive solar battery review here.

Step 2: Determine The Number of Panels That Can Fit On Your Roof

In general, a size of 1.7m^2 is used for solar panels in the UK i.e. you calculate 1.7m^2 by the area of the roof.

For example, if the area of your roof is 10m x 4m = 40 m^2, divide 40 by 1.7m to give you 23.

This would mean that you can fit approximately up to 23 panels on your roof. Now, that’s a great way to outdo the neighbours.

Step 3: Determine the Array Size

To work out the solar array size you require, you can use the following formula: 

For example:

The average array size in the UK is 3.5kWp = 350 Watt x 10 i.e. you would need 10 x 350 Watt panels to achieve the 3.5kWp array. 

Check out our full in-depth article on whether solar is worth it in the UK. 

Step 4: Determine Your Solar Radiation Input Factor 

The solar radiation factor (kk) is essentially the amount of sun your roof receives, which depends on the location of your home and the angle and pitch of your roof. 

You do this by determining the following: 

• Determine the direction your roof faces.

• Determine the angle and pitch of your roof. 

• Determine which zone you reside in. 

Three simple steps will have you bragging about your solar radiation input factor for many birthday parties to come. 

Step 5: Determine Your Shade Factor 

The ideal location is to have a roof with no shade at all. 

If you don't have any shade, use 1 for this part of the calculation. 

If you do, you will need to follow these steps on the MCS website. 

Step 6: Plug in Your Numbers 

Once you have followed the above procedures, you can then plug your numbers into the formula above. 

If this is too complicated, simply use our solar calculator here and it will show you exactly how many solar panels you will need. 

Still, learning about solar? Check out our guides on how many solar panels you need and how solar car charging works. 

How Solar Panel Wattage Impacts Energy Generation Capacity

Naturally, the higher a solar panel’s wattage, the more energy it will produce. The same applies on a larger scale for a solar array.

However, it’s important to note that efficiency also matters. The average silicon-based solar panel has an energy efficiency of around 15-22%.

Efficiency matters as a higher efficiency often reflects a higher quality solar product and means your system will be able to produce more energy throughout the year. 

Other Efficiency and Power Generation Factors

Efficiency and power generation are affected by more than just size and the quality of the panel.

When it comes to energy efficiency, you’ll also want to consider how well a panel is likely to maintain its efficiency over time.

You can generally judge this best by considering the guarantees offered by the manufacturer.

For example, the REA Fusion Energy solar panels that are exclusive to Heatable have an efficiency rating of 24%. 

As for other power generation factors, you’ll also want to keep the following in mind:

• Number of panels

• The average number of sunlight hours in your region

• Roof orientation

• Whether your panels are obscured from sunlight at any time of the day

Residential Solar Panel Sizes in the UK

Average Power Output of Residential Solar Panels

As mentioned, residential solar panels tend to offer an output of 250-400 watts each, although more powerful options can be found on the market.

For instance, the Jinko Solar Tiger NEO 72HL4 offers a whopping output of 550-575 watts, it the physical panel size is over 2.1m and 1.05m wide.

Factors for Sizing Residential Solar Panels

When looking for the correct sized panels for your home (by any and all definitions), there are several key considerations to take on board.

These include the following factors: 

Available Roof Space and Orientation

Firstly, think about approximately what dimensions your solar panels must have.

By looking at how much roof space you have, you’ll get an idea of how many panels would fit.

For orientation, a south-facing roof is ideal. However, an east- or west-facing roof can work too. It’s not a good idea to fit solar panels to a north-facing roof.

If there isn’t sufficient room for enough panels of a certain output (e.g. 300 watts), you can still consider opting for fewer panels, each with a higher output.

Many customers are now selecting to install much more efficient solar panels due to rising energy demands and technology improvements.

Panels like the REA power fusion supplied by Heatable feature bi-facial receptors and in tests have produced as much as 18% more energy compared to other tier-one panels.

This way, you could still get the overall output you’re looking for from a solar system.

If you are researching solar panel companies, you may find our resources valuable. Check out our comprehensive comparison of the best solar panel companies in the UK, learn about the Distribution Network Operator (DNO) process, and explore our detailed solar panel guide and solar advice section for expert insights and recommendations.

Energy consumption and household needs

A major consideration is how much energy you’d require to meet your household needs.

Of course, solar arrays tend not to meet a household's entire electricity demand. This is largely due to the fact that the energy produced from solar arrays is real-time and unless you consume it, you’ll export it to the grid (which you could be paid for under the SEG scheme).

MCS estimates that only about 30% of all the energy produced by a typical solar system without battery storage would be consumed at home, the rest would be exported. Don’t panic though, installing a battery dramatically improves this to as much as 80%!

Spend time considering how much of your household’s electricity needs you’d like a solar array to meet.

Then, look at the scale and power output that is feasible for your roof and figure out what setup would best suit your energy needs.

Ultimately, you’ll still want to run through things with your MCS-certified solar installer before making a final decision.

Budget considerations

When attempting to narrow down the ideal solar array for your home, don’t forget to take your budget into account.

The best solar panels on the market tend to cost between £200 and £400 per panel.

However, budget-friendly options do exist, such as JA Solar’s JAM60S20 available from just £100 per panel.

Be sure to keep each of these three points in mind when figuring out the perfect solar system for you and your household.

We have also reviewed the best solar panels and covered how long solar panels last in the UK. 

Commercial and Utility-Scale Solar Panel Sizes in the UK

For commercial and utility purposes, larger solar panels (often in dimensions but certainly in wattage) are needed.

Use of Panels for Commercial and Utility-Scale Projects

According to IBIS World, nearly 2,300 UK businesses have solar panel installations as of 2023.

This represents a 7.2% increase from 2022.

Businesses tend to require larger panels (i.e. those exceeding 400 watts) to help meet their high energy demands.

Businesses may opt for solar installation for a number of reasons.

Among the core benefits of solar panels to a commercial premise include reduced energy bills, increased energy self-reliance, and the capacity to apply for a 100% capital tax allowance in the first year post-installation (GOV.UK).

Characteristics of commercial and utility-scale solar panels

Higher wattage ranges

Naturally, commercial and utility-scale solar panels generally have higher power outputs.

After all, if a business were to use panels similar in size to domestic properties, they’d need a very large number of panels.

Opting for panels with higher outputs, it helps to keep the scale of the installation to a minimum and reduce the overall complexity of the setup (which is better from a maintenance perspective).

As mentioned, solar panels used for commercial and utility purposes are likely to have an output of 400 watts or more.

Standardised dimensions and considerations for efficient installation

As alluded to, you’ll want your solar panels to have the same dimensions to make the installation as smooth as possible.

Standardized dimensions can also lower the risk of your installation becoming an eyesore.

This is arguably a bigger concern for businesses than households due to PR.

Other pointers to consider for an efficient installation are:

• Hiring a reputable and highly-rated solar installation company

• Ensuring the company you hire have MCS certified installers

• Preparing your business and the relevant installation area for the solar setup

• Make sure that your setup plan is totally concrete before the day of installation

• Advantages of Larger Panels for Commercial and Utility-Scale Applications

Enhanced land utilisation and reduced installation costs

Using more powerful panels helps make better use of your land/company’s land by limiting the number of panels required for an installation.

What’s more, the lower the number of panels being installed, the quicker the installation job is likely to be. This will likely reduce the overall cost of labour.

Also, if you can find powerful panels with good value for money, you may even save on supply costs too.

Scalability and higher overall energy output

Using larger panels and limiting the number used in the initial installation makes scalability more plausible.

After all, with fewer panels fitted in the first place, there’s more space to add more panels in the future.

Ultimately, this means more room to increase the energy output of your solar array with time.

Just be sure to take the total weight of a larger solar system into consideration to ensure the safe scalability that your roof can handle (if fitted to a roof).

Efficiency Considerations for Solar Panels

Energy efficiency is a key factor to consider when finding the right solar panels for you.

Significance of Panel Efficiency for Maximising Energy Generation

More efficient solar panels will offer more energy for your commercial or utility needs.

Also, solar panels with high efficiency tend to be more reliable. All in all, high efficiency is a good indicator of a high-quality product.

Factors Influencing Panel Efficiency

Technological advancements and improvements

The energy efficiency of solar panels can be shaped by a wide range of factors.

For one, some solar panel units are newer or have otherwise made better use of cutting-edge technology.

While these may be more expensive (in most cases), highly efficient panels that use the latest technology will often provide good value for money.

Solar irradiation levels and environmental conditions

Solar irradiance (i.e. how much energy is received from the sun at any given time) is a key factor in how efficient solar panels are at any moment.

For instance, according to Current Results, Glasgow sees 1,280 hours of sunlight annually, whereas Plymouth enjoys about 1,730 hours per year.

Aside from how much sunlight your region sees, local solar irradiation levels can be influenced by:

• Local weather conditions

• Very localised factors like trees obscuring sunlight at certain times of the day

• Time of the day

• What direction do your solar panels face *

*South-facing roofs or setups are ideal for harnessing solar energy.

Selecting High-quality Panels with Optimised Efficiency

Be sure to opt for high-quality solar panels with top-of-the-market efficiency.

We recommend looking into the best solar panels on the market while narrowing your search down to those suitable for your needs.

Opting for a high-quality brand and product can ensure good value for money.

This will also hopefully prolong the time between now and when replacements or repair work will be required as much as possible.

Future Trends and Innovations in Solar Panel Sizes

Whether you’re curious for purposes of scalability or to consider an installation at a later date, you’ll want to know about the future of solar.

Emerging Trends in Sizes and Designs

With the market size of solar technology expected to grow and further technological innovations, we can expect a future with thinner, slicker, and more efficient solar panels.

This will allow panels with smaller dimensions and lower weight to offer improved performance stats over time, allowing for smaller and more efficient installations.

Innovative Solar Technologies

There is a wide range of innovative technologies impacting panel size and efficiency. For example, one recent innovation is that of hybrid solar panels.

Hybrid solar panels consist of two or more materials used to provide solar panels with innovative characteristics. The idea is to enhance overall performance, including improved efficiency.

To provide an example, Fusion Energy’s panels (which are exclusive to heatable) employ N-type solar cells with M10 Topcon. Topcon refers to the use of a thin tunnel oxide layer.

The purpose of this is to keep the front and back contacts of the cell separate, thus reducing recombination losses.

Essentially, recombination loss is the process of solar cells losing electrical energy.

Therefore, reducing these losses helps to prevent unnecessary efficiency losses for the panel as a whole. All in all, hybrid solar panels can offer greater efficiency, often reaching up to 23%.

Other innovative developments that may supercharge our solar future include:

Biohybrid Solar Cells - Combination of organic and inorganic matter that could potentially lead to 100% energy efficiency.

Cadmium Telluride Solar Cells - Panels made of these cells could be made significantly cheaper, thus making panels with high outputs more affordable.

Concentrated PV Cells - With advanced designs and functions, concentrated PV cells can offer higher efficiency levels. The US National Renewable Energy Laboratory reports that a project run by one laboratory organization aims for efficiency levels of 41%.

Potential Impact of Developments on the Future of Solar in the UK

Depending on how the industry’s future pans out, there is plenty of potential for new developments and innovations to reshape solar in the UK.

After all, if technological advancements can bring increased efficiency and reduced costs, more households and businesses across the UK will be more incentivized to opt for solar installation.

Advanced solar technology such as those based on concentrated PV cells or even biohybrid solar cells could lead to a massive acceleration in the number of solar instalments nationwide.

Solar Panel Sizes Conclusion

In summary, understanding solar panel sizes (dimensions, wattage, and weight) is important for effective energy generation.

Moreover, getting the sizing right also matters to ensure you can fit all the panels on your roof required and that it can withstand their weight.

Whether for residential or commercial applications, be sure to consider the following when attempting to size a solar panel by all three definitions.

• The total power output of the solar system required

• The space available on your roof/land for a solar array

• The load-bearing capacity of your roof (if opting for a roof-based instalment)

• The quality and efficiency of the panels

• Whether you need more powerful panels to fit on your roof that also meet your energy requirements from a solar system

Be sure to do your research to find solar power options in line with your energy needs.

Households may want to look into companies such as REA Fusion Energy, Sunpower, Project Solar, LG and Panasonic.

On the other hand, for commercial and utility applications, consider brands like REA Fusion Energy (again), Sharp, and Jinko Solar.

In general, businesses should look for monocrystalline solar panels (a categorization based on the material used).

This is because monocrystalline panels are generally more efficient and tend to last longer.

Next Steps For Your Solar Journey:

When planning to install solar panels for your home, there are several important factors to consider. Make sure to refer to the following guides to help you make informed decisions:

• How much do solar panels cost? 

• Are solar panels worth it for your home? 

• Is your roof suitable for solar panels? 

• What are the best solar panels available? 

• Is battery storage worth it? 

• Tier 1 vs Tier 2 Solar Panels

To dive deeper into these topics, head over to our advice section, check out our YouTube channel for informative videos, or read a customer case study to see how others have benefited from their solar installation. 

Get a Quote for Solar Today 

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• MCS Accredited: Our accreditation by the Microgeneration Certification Scheme (MCS) ensures high-quality standards.

• Exclusive Panels: We offer REA Fusion solar panels, available only through Heatable.

• Consumer Protection: As members of the HIES consumer code, we provide 2-year deposit protection.

• Flexible Payment Options: Choose from multiple payment methods, including finance options.

• Fixed Price Guarantee: Enjoy transparency with no hidden costs.

• Save Your Quote: You can save your quote and decide later.

• Bespoke Design Tool: Draw your own conclusion (literally) on whether solar is worth it for you, here.