How Many Solar Panels Will You Need?

Scotland might not be the first place that springs to mind when you think of sunshine-powered solar panels, but you’d be surprised at the growing number of households turning to this green technology.

Even under frequent clouds, solar panels are proving to be an effective way to generate electricity for homes across the country. They’re a smart choice that contributes significantly to the nation’s renewable energy effort.

What’s more, adopting solar technology is financially smart too. Thanks to supportive initiatives, like the ECO4 scheme, installing solar panels is a cost-effective choice.

But before you join the many other solar-powered homes, there’s a critical question to answer: “How many solar panels do you need?” Getting this right is key to maximising the benefits.

With our comprehensive guide, you’ll find the right number of solar panels for your needs, break down the costs involved, and explore the incentives available to Scottish homeowners.


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Understanding Your Regular Electricity Usage

Before you can determine how many solar panels you’ll need, you first need to know your regular electricity usage.

Residential solar panels typically generate between 250 and 400 watts (W) per hour, with solar panel systems varying in size from 1kW to 5kW. In the Scottish climate, accounting for cloudy days, a 5kW system can produce around 4,500 kilowatt hours (kWh) per year.

However, the ideal setup for your home depends on your lifestyle and needs, such as:

  • The size of your home
  • The number of people living there
  • Whether you use electricity solely or in combination with gas
  • Your work habits (e.g. working from home)
  • The insulation quality of your home
  • Your energy goals (full solar power conversion or partial)
  • Your typical electricity usage

To gauge your electricity consumption, it’s wise to review your electricity bills from the past year, noting any seasonal differences. For a more hands-on approach, a smart meter can offer valuable insights, providing real-time data on your energy consumption and helping you determine the exact amount of solar panels you’ll need.

For context, the average Scottish home consumes around 2,700 kWh of electricity per year. If your usage aligns with this, a 4kW system could suffice, possibly even a 3kW solar panel system. Typically, a 3kW system involves 12 panels, but this number may vary based on the panel’s wattage.

If your home is larger, or you have a bustling household or run a home business, your energy needs will naturally increase, requiring more panels.

Here’s a simplified guide to give you an idea of what might suit your home, based on the number of occupants:

  • 2 people (flat or single-bedroom home) – A 3kW system, typically around 6-12 solar panels.
  • 3 people (2-3 bedroom home) – A 4kW system, requiring about 14-16 solar panels.
  • 4 people (3+ bedroom home) – A 5kW system, around 16-20 solar panels.
  • 5+ people (4+ bedroom home) – A 6kW system, around 18-24 solar panels.

These are only general guidelines. Every home is unique, so having a professional assessment will ensure your solar panel system is a perfect fit for your energy goals.

For enhanced efficiency, especially during Scotland’s darker months, consider a solar battery storage system. It saves surplus power on sunny days, which you can use when it’s overcast.

What Is the Average Number of Solar Panels in a Scottish Home?

The amount of solar panels you might see on a typical Scottish roof varies, mainly based on how many people occupy the home and the home’s energy goals.

For example, if a home installs a 3kW system with 250W panels, they’ll need 12 solar panels. But for a bigger 6kW system, the home will need 24.

In Scotland, a household with two to three people uses about 2,700 kWh of electricity per year on average. Based on this consumption level, the size of the solar panel system they need can vary.

For big families of five or more, a 6kW system is common. This setup usually has between 18 and 24 solar panels. For a home with four people, a 5kW system works well, needing around 16 to 20 panels. A 4kW system is a popular choice for homes with three people, needing 14-16 panels.

Another factor that dictates the average number of solar panels in a Scottish home is whether it’s used to cover all energy needs or just some.

Scottish homes usually use between 3 kWh and 6 kWh of energy each day. But, if a homeowner decides to use solar power only for some of their energy use, they need fewer solar panels. This choice lets people adjust their solar panel systems to match their energy use and budget.

Solar Panels Country Home

What Factors Influence the Number of Solar Panels a Home Needs?

Your home’s electricity usage

Understanding your home’s electricity consumption is essential. Take a look at your energy bills over the past year to determine changes in your usage habits – these can be because of seasonal changes or changes in your home’s usage patterns.

Remember, your goal is to match how much energy your solar system generates with your consumption. You want to strike a balance that caters to your needs while considering efficiency and cost.

Geographic location

Your location affects how much sun you get, impacting your panels’ electricity output. Panels work on cloudy days but do best in direct sunlight.

While southern regions enjoy longer sun hours, northern areas, particularly northern Scotland, receive fewer, which affects the solar panels’ productivity.

It’s not only about the number of sunny days but also the intensity of sunlight. You might need additional panels in regions with less intense sunlight to compensate for the reduced solar output.

For example, 10 panels at 350W each make around 2,978 kWh yearly in southern England, but only around 2,221 kWh in northern Scotland. You might need 1-3 more panels in Scotland to match England’s output.

Type of solar panel and efficiency rate

Solar panels come in different types, each with different efficiencies. Polycrystalline panels average 13% – 16% efficiency, while monocrystalline ones range from 18% – 24%.

Monocrystalline panels, with their higher efficiency, could be a better investment in the long run despite the higher upfront cost, especially for homes with limited roof space.

On the other hand, polycrystalline panels offer a budget-friendly option but might demand additional panel installation to meet your energy needs.

Size of solar panel

The size of the solar panel corresponds with the power output. A standard 350W panel can generate around 265 kWh per year in the UK, but this can vary.

Let’s look at an example: To estimate how many panels a home needs, divide the yearly electricity use by 265. A 4,000 kWh household needs roughly 16 panels. As a general rule of thumb across the UK, for every 1 kW on your roof, expect 760 kWh of production.

Installed capacity

The total power of your setup equals the number of panels multiplied by each panel’s power (Wp), indicating the electricity your system can produce.

For example: A 300 Wp panel x 6 panels = 1,800 Wp or 1,800 kWh yearly.

Keep in mind that the watt-peak (Wp) rating given by manufacturers is based on perfect solar conditions. Real-world conditions aren’t always ideal. Local weather variations, shading, and temperature changes can all impact solar energy production.

So, to accurately determine the number of panels your home requires, you must also assess the direction your roof faces and your home’s specific location.

Orientation of the roof

Across the UK, south-facing solar panels work best for maximum sun exposure throughout the day. East- or west-facing roofs generate 20% – 30% less power, but can still be effective.

Any non-south-facing roofs might need extra panels or advanced positioning solutions (like solar tracking mounts) to match the energy output of south-facing installations.

You need to analyse your roof’s orientation, tilt, and any potential obstructions like trees or chimneys to optimise your solar setup effectively.

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How to Calculate the Number of Solar Panels You Need?

Wondering how many solar panels you need? It’s actually incredibly straightforward to calculate! Here’s a quick step-by-step guide:

  1. Calculate your daily electricity usage

First off, grab your electricity bill. You can use either a physical copy or check your online account. It will either show your electricity usage monthly or annually.

If it’s monthly, just multiply the number by 12 to get a yearly figure. This usage is in kWh. Divide your yearly usage by 365 (the number of days in a year), and you’ve got your daily consumption.

For example:

Yearly usage = 3,500 kWh

3,500 ÷ 365 = around 9.6kWh daily (or 9,600Wh)

  1. Determine your solar energy goals

Next, decide what portion of your electricity you’d like to come from solar, whether it’s completely solar or just partial. Keep in mind that more solar power means a bigger initial investment.

In our case:

Daily usage = 9.6kWh (9,600Wh), and you wish to go 100% solar.

  1. Figure out your area’s peak sunlight hours

This part can be a bit tricky. You need to figure out the average sunlight hours for your specific area. Naturally, this can change quite a bit, depending on the time of year and where exactly in Scotland you live, such as closer south or closer north.

Scotland typically experiences a lower range of peak sun hours, around 2-3 hours only. In this case, we’ll use 3 hours of peak sunlight.

So, we have:

Daily usage = 9.6kWh (9,600Wh), aiming for 100% solar, with 3 hours of peak sunlight.

  1. Identify each solar panel’s power

Now, think about the power each solar panel can provide. This will depend on the type and size of the solar panel. Most UK home solar panels fall between 200W and 450W, with the average being 350W.

For our example, we’ll use 350W.

Our setup so far:

Daily usage = 9.6kWh (9,600Wh), aiming for 100% solar, with 3 hours of sunlight, and each panel has a 350W rating.

  1. Calculate the daily solar output

To calculate how much energy output each solar panel is producing, use this formula: Solar panel wattage x average sunlight hours x 0.75 (this accounts for losses like not-so-perfect positioning or occasional shading)

For our example:

350W x 3 hours x 0.75 = about 787.5Wh daily.

  1. Identify the amount of solar panels you need

The final step is to divide your daily usage (from step 1) by the daily solar output (step 5).

For our example:

9,600Wh ÷ 787.5Wh = roughly 12 panels.

With 350W panels, you’ll need about 12 solar panels for your daily needs. It’s smart to think about getting an extra panel or two since you can sell back excess electricity. This can help pay off your solar investment.

What Type of Solar Panels Should I Install?

Having mentioned the two most popular types of solar panels earlier, it’s key to know that they’re not only grouped by their output but also the photovoltaic materials they’re made of.

Therefore, understanding the type of material will help guide your decision on the amount of solar panels you need, as well as which is a better match for your solar energy goals.

Polycrystalline and monocrystalline are two of the most popular types of solar panels used across the UK.

Monocrystalline solar panels

The most popular choice, monocrystalline solar panels stand out with efficiency ratings between 18% and 24%. Their higher efficiency is due to the use of single-crystal silicon, which creates an easier path for electrons and leads to improved performance, even in lower light.

Aside from their efficiency, monocrystalline panels need less space for installation and are more durable under tough weather conditions. They also offer a sleek, uniform look with their single-crystal construction, which is attractive for homeowners concerned about aesthetics. However, these benefits also make this type of solar panel more expensive.

Over the long term, monocrystalline solar panels are beneficial due to their durability and ability to perform well even in high temperatures. This means they have a longer operational lifespan.

Polycrystalline solar panels

The other common type of solar panel is polycrystalline, which is slightly less efficient, with an average efficiency rating of around 13% – 16%. While slightly lower than monocrystalline solar panels, they offer a more budget-friendly price point.

These solar panels are made of multiple silicon crystals, which limits electricity flow, hence the lower efficiency. This means you may need more of these panels to fulfil the same power output as monocrystalline solar panels. Consequently, you’ll also need more roof space.

Additionally, these solar panels tend to have a shorter lifespan due to increased sensitivity to temperature changes.

Alternative: thin-film solar panels

Besides crystalline-based solar panels, there is another option: thin-film solar panels. These are the least efficient of the three, with about a 7% conversion rate. However, they are the most economical option because they use less material in production.

The drawback is you will need a large number to produce enough energy, which means they’re not ideal for smaller spaces. They also tend to degrade faster than crystalline types but can function in a variety of light conditions, even in less sunny environments.

What Is the Cost Of Solar Panels?

Deciding to install solar panels is a big step, and understanding the cost costs involved is crucial. In Scotland, like in many places across the UK, the popularity of solar panels is on the rise, and thankfully, prices are more affordable than ever before.

Solar panel costs have significantly dropped by approximately 70% since 2010. This decrease is due to the new improvements in technology and a surge in global demand, making solar panels more accessible to the average homeowner.

But, pinning down the exact cost can be tricky because it depends on various factors. These include the kind of solar panels you choose, their size, how much electricity your home uses, and your specific location within Scotland.

For a typical two-person home in Scotland, a 3kW solar panel system is common. The cost of such a system, including installation, usually falls between £6,000 and £7,000. However, this price can vary based on the system’s specifics and the nature of your property.

To give you a clearer idea, here are some rough estimates of how much solar panels cost in Scotland:

  • 3kW system
    • Number of solar panels: 12
    • Price: £5,000-£6,000
  • 4kW system
    • Number of solar panels: 16
    • Price: £6,000-£8,000
  • 5kW system
    • Number of solar panels: 20
    • Price: £7,000-£9,000
  • 6kW system
    • Number of solar panels: 24
    • Price: £8,000-£10,000
  • 13kW system
    • Number of solar panels: 48
    • Price: £11,000-£13,000

These figures are estimates and the actual costs can change due to several reasons like the specific brand of solar panels, the local going rates in your area, or any unique installation challenges your property presents.

While the initial expenses for solar panel installation might seem steep, the long-term savings are significant. On average, it takes about six years for the savings from solar panels to cover the cost.

The good news is that Scottish homeowners can take advantage of the Smart Export Guarantee (SEG) scheme to speed this up. With SEG, if your solar system generates more power than you use, you will be paid for sending that extra power back to the national grid. This not only trims your energy bills but also helps your solar investment pay off faster.

Though solar panel costs have seen a decline, they might still feel pricey to some in Scotland. However, given the long-term benefits and savings, many find it a worthwhile investment.

solar panels small town Scotland

Guide To Solar Panel Sizes

Having solar panels installed is more than just how many you need; the size and capacity of each panel are key too.

Solar panels in the UK come in various dimensions and sizes, depending on the manufacturer and type of panel. There is no universal fit, which may complicate things but it also offers you the freedom to pick panels that suit your specific needs and space.

When selecting solar panels, focus on the size (in terms of energy output) rather than just dimensions, as this impacts the amount of energy you can generate. However, your choice will inevitably depend on the roof space you have available.

The average size of solar panels

Solar panel “size” can refer to several things: power output (wattage), physical dimensions, or weight.

  1. Power output

This is measured in wattage, indicating the electricity the panel produces per hour.

Residential panels typically range from 250W to 400W, while commercial ones might offer 400W to 600W. A standard home solar system in the UK is usually between 3kW and 5kW, consisting of around 6-12 panels. This is designed to meet the average household energy needs. About 2,700 kWh to 2,900 kWh, as per Ofgem.

  1. Physical dimensions

The size of your solar panel also refers to its actual physical size. Residential panels are usually 65 inches long and 39 inches wide, with a thickness of 1.2 inches to 2 inches. It’s essential they fit well on your roof.

  1. Weight

Lastly, weight refers to how heavy the solar panels are, which is important because your roof must support it. Standard residential panels, covering roughly 1.4 square metres, have slight size variations based on the manufacturer.

Choosing the right panel size for your home

While each brand of solar panel might offer slightly different panel sizes, a standard residential panel is usually 1,650 mm x 990 mm. Most home systems use 60-cell panels, and the full system (known as an array) consists of several panels installed together.

To figure out the right size for your home, follow these steps:

  1. Determine the number of panels: As we’ve mentioned before, consider your energy goals. Most home systems are between 1kW and 4kW. The larger the system, the more energy you produce and save.
  2. Measure the roof dimensions: Most Scottish homes can accommodate solar panels, but obstacles like windows or chimneys may limit space. A 1kW system needs about 8 square metres, while a 4kW system requires around 28 square metres.
  3. Check the roof strength: Residential panels typically weigh between 18kg and 20kg each, and your roof must hold this weight. Thankfully, solar panel installers will assess this during an initial inspection.


The average number of solar panels you’ll need in a Scottish home primarily depends on your home’s electricity consumption, the type and size of panels, and the amount of sunlight your area receives.

Generally, most residential solar panel systems in Scotland, and the broader UK, are rated between 3kW and 4kW. This is roughly 6-12 panels and 14-16 panels respectively.

For a 5kW system, you need around 12 panels if each has a 415W capacity. This setup requires approximately 24 square metres of roof space. However, it also depends on the average energy consumption and number of occupants per home. For example, a home with four people may require 16-20 solar panels with a 5kW system.

Technically, there’s no limit to how many solar panels you can install on your property, as long as you comply with local planning regulations. However, it’s important to balance your system’s size with your household’s energy needs. Installing an excessively large system can lead to unnecessary expenses, as you might end up with more power than you can use or store.

Solar panels can last a solid 25-30 years. To ensure they reach this lifespan, invest in a high-quality solar PV system and work with an expert solar panel installer for the installation process.

Yes! Residents have access to several grants for a solar panel system in Scotland. The main grants available are the Home Energy Scotland Grant and Loan, VAT reduction, Smart Export Guarantee (SEG), ECO4 scheme, and Warmer Homes Scotland.


Embracing solar energy in Scotland is a forward-thinking move, both environmentally and financially. As the demand for cleaner energy sources grows, the cost of solar panel installations continues to decrease, making it a viable option for many Scottish homeowners.

Calculating the right number of how many solar panels you’ll need is crucial, as it directly influences how efficient the system is, as well as your energy bills and comfort.

It’s not only about how many solar panels you can fit on your roof but also about how much energy you use. Too many panels can cost more than you need to spend, while too few might not give you all the energy you need.

Thankfully, different types and sizes of solar panels are available, allowing you to custom-fit the exact system to your needs.