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Last updated: 20 June 2024

How Many Solar Panels Do I Need in the UK? | 2024 Guide

how many solar panels
  • On average, a 1-2 bedroom house requires 4-8 panels (2-3kW), a 2-3 bedroom house needs between 8 and 13 panels (4-5kW), and a 4-5 bedroom household in the UK will need 13 to 16 solar panels at 6kW total.
  • Your electricity consumption, the direction of your roof, sunlight hours, and the roof space all determine the size of the system you need.
  • Solar panels for the average 3-bedroom house will save between £440 to £660, taking 9 years to break even while generating a return of £5,500 to £8,500.

Before installing solar panels for your home, there is one key question you should ask yourself, namely: How many solar panels do I need? The answer depends on several factors, such as:

  • Your home’s annual electricity consumption (measured in kWh)
  • The efficiency of your solar panels 
  • The number of sunlight hours at your location
  • The size of your home

We will go into more detail about how to account for each of these factors in your calculations throughout this article. As an estimate, the table below can provide you an indication of the number of solar panels you’ll need based on your situation: 

Number of solar panels needed
Household SizeAverage Annual Electricity ConsumptionEstimated Number of Solar Panels (350W or 450W)
1 - 2 bedrooms1,800kWh4 - 8
2 - 3 bedrooms2,700kWh8 - 13
4 - 5 bedrooms4,100kWh13 - 16

Since every home is different, you will want to consult a solar expert who can help you determine exactly how many solar panels you need. This way, you can fully enjoy the benefits of solar energy

Finding a reliable installer can be a daunting task that can lead to hours of research without a guarantee that you will get any fruitful results. To help you avoid wasting your time, we can put you in touch with solar panel installers vetted by us!

By clicking below, you can fill in our 30-second contact form and receive quotes from up to 4 trusted solar experts in your area. With multiple options, you can choose the installer you want to work with and find the best deal. All quotes are completely free and non-binding, so click the button below to get started.

How many solar panels do I need?

To calculate the number of solar panels you need, first determine your annual electricity consumption in kilowatt-hours (kWh). An average average UK household consumes about 2,900 kWh annually.

Solar panels' output varies by model but assume an average production of 350 watts per panel under optimal conditions. 

Therefore, to cover a medium-low consumption profile (1,800 kWh/year), you'd need approximately 6 solar panels. For medium usage (2,700 kWh/year), 9 panels would suffice. Households with medium-high consumption (4,100 kWh/year) should consider 13 panels.

Keep in mind that these estimates are based on average conditions and actual needs may vary based on your location's sunlight exposure, the panels' efficiency, and your household’s energy consumption. As the number of residents increases, so do the energy consumption levels and solar panel sizes.

However, if you're only looking to charge a limited space, you might not need a full system. Putting solar panels on a shed roof, for example, only takes up a few meters to get the job done. Most shed roofs can fit 2 or 3 panels, so getting 450W capacity panels could cover most appliances needed in a shed.

How many solar panels you will need on average

You can consult the table below for an idea of the number of solar panels required to power homes of different sizes.

Number of solar panels needed based on annual consumption
House sizeAnnual energy consumptionNumber of solar panels (350W)Number of solar panels (450W)
1-2 bedroom1,800kWh5 - 84 - 6
2-3 bedrooms2,700kWh10 - 138 - 10
4-5 bedrooms4,100kWh1613
*These numbers are rough estimates. Your home’s energy needs may vary.

The table gives a general estimate of how many solar panels you might need to offset your electricity use in the UK, but the exact number of panels will depend on several factors, including:

  • Your electricity consumption: Check your utility bills to determine your annual kWh usage.
  • The efficiency of your solar panels: Higher efficiency panels, such as bifacial solar panels, take up less space and need fewer cells to achieve the same output.
  • Sunlight hours in your region: Not all regions have the same hours of sunlight per day.
  • Roof size and orientation: South-facing roofs that allow for solar panels to achieve a 30° to 50° angle allow for better access to sunlight.

The average number of solar panels will also be determined by whether you would like your solar panels to generate all your electricity needs or only a percentage.

A medium-sized UK home typically consumes 2,700kWh of energy annually and some UK homeowners use solar energy to power only parts of their energy consumption, which would then reduce the number of solar panels installed.

The image below is based on 350W panels.

number of panels

How to calculate how many solar panels you need?

To calculate what solar system size you need, you should first know the amount of energy that you need to generate from your solar system daily. The other important things are the sun hours in your area and your roof space, as this can help you determine how many solar panels your roof can accommodate.

For instance, an additional possibility in the event of insufficient roof space can be to opt for garden solar panels.

How many solar panels formula

If you’re wondering “How many solar panels can I have on my roof?”, you can use 2m2 per panel as a general rule of thumb and see how many you can fit on your roof space. 

An average 3-bedroom home consumes around 3,000 kWh of electricity per year, which can be supplied by a 3kW solar system consisting of 8 solar panels. Larger homes may require a 6kW system made up of 16 panels. That said, the number of solar panels needed to power a house depends on several factors such as solar panel efficiency, sunlight hours, and annual electricity consumption. 

What size solar system do I need?
Size of solar systemNumber of 350W panelsEstimated surface area
*This table assumes 350W Solar Panel dimensions: 2m² per panel

To find out how many you need to install on your roof, you can check your monthly energy bills. These can provide information on the amount of energy that you consume per day, and therefore how much energy you need your solar panels to generate daily. You can follow the same process to find the right commercial solar panel system size if you want to invest in solar PV for your business.

Naturally, cost is an important determining factor for how many solar panels you need. The cost of solar panels in the UK depends on several factors including the size and type of solar panels. The cost ranges from £4,500 - £5,500 to £12,000 - £13,000 for solar panel system sizes ranging from 3 kW to 12 kW solar systems in the UK.

You can find an estimation of prices per solar panel system size in the table below:

Solar panel system costs + break-even points
Solar panel sizeNumber of 350W PanelsPriceBreak-even point (years)Return on investment
3kW8£4,500 - £5,5009£5,500 - £6,500
4kW10£5,000 - £6,0008£10,500 - £11,500
5kW13£7,500 - £8,50010£8,000 - £9,000
6kW16£9,500 - £10,50010£15,000 - £16,000
*These prices are estimates based on a system using 350W panels. Break-even points calculations are based on Ofgems Typical Domestic Consumption Values. These figures are intended as guidance and not as an exact price. We always recommend getting a tailored quote for your property.

Other factors that may affect the cost of solar panels include:

  • The cost of solar panels in your area
  • Brand or supplier costs
  • Labour costs in your area (unless you're installing a DIY solar system)
  • Site complexities that may require more labour hours

Cheap solar panels are also an option, but be cautious of extremely low prices. These panels are usually less efficient, have shorter warranties, or are more prone to performance issues. It's important to find a balance between affordability and quality

What factors influence the number of solar panels a home needs?

To determine the size of the panels that you need for your house, you need to know the following:

  1. How many sun hours does your home receive?
  2. The direction your roof faces (south-facing roofs perform better).
  3. The capacity of your roof: how much space in square meters is available?
  4. Dimensions of solar panels per size or brand.

Sun hours

It is important to be aware that different regions in the UK have different sun hours per day: England has 4.1, Scotland has 3.7, Northern Ireland 3.2 and Wales 3.3. This means that it could be more beneficial to install solar panels in Scotland, compared to solar panels in Northern Ireland. It is therefore important that you consult your local installer for guidance. This could result in bringing down the solar panel price in Wales, England, Scotland or Northern Ireland.

Solar panels generate different amounts of energy depending on their wattage size or rating. A 350 watt panel will generate up to 350 watts per sun hour while a 400 watt solar panel can generate up to 400 watts per sun hour (under ideal conditions). This is why it is important to know the amount of energy you need before determining solar panel sizes.

Roof orientation and direction

South-facing roofs with a slight tilt towards the West perform the best in the UK. Countries such as Australia will require solar panels facing in the opposite direction. There are minute differences throughout the UK, but this rule generally applies throughout the region.

The optimum solar panel angle in the UK is between 30° to 50°. It is recommended to adjust the angles throughout the year to accommodate the changing position of the sun.

Roof space & capacity

How much space you have on your roof is also a major consideration. Solar panels are light enough to rest on roofs without any damage. That said, not every section of your roof may be facing the correct direction or allow for the right angle to make use of solar technologies.

This also relates to the size of solar panels, both in terms of capacity and their physical dimensions.

Size of solar panels

Most residential solar panels are between 300W and 400W.

how many solar panels do I need calculation

The capacity of your roof impacts the number of solar panels you can install and therefore how much energy you can generate. This is also because different solar panel sizes have different dimensions.

If you are installing 12 solar panels (350W), they would require a surface area of 24m². It is therefore important to know how much space you have. The table below outlines the average solar panel dimensions and weight per system size.

Required Solar Panel Surface Area
Solar panel size (W)*Solar panel dimensions*Weight per panel
3501.6m x 1m18kg
4001.67m x 1m18kg
4501.9m x 1m21.6kg
*It is important to note that different brands may have different solar panel dimensions.

When deciding how many solar panels you need, it can be difficult to account for all the factors involved. This is why it’s best to consult a reliable installer and have them provide you with an estimate. Finding a reliable installer can take days of difficult research and calling up companies. If that sounds like a hassle, why not try out our handy service?

We can easily provide you with up to 4 free non-binding solar panel quotes in the UK and all you have to do is fill out a 30-second form. Click the button below to get started.

How many solar panels do you need for running a house off-grid?

How many solar panels do I need for an off-grid house

The average off-grid home will require a 7kW to 10kW solar panel system. Why so much compared to the modest 4kW system required for on-grid homes? Off-grid power has a lot more considerations.

Going off-grid usually requires a high-power system since you will often be compensating not just for electricity but also for gas. Therefore, the calculations are drastically different already. Added to this, you also need to compensate for the seasonal dips in energy generation during the winter.

These systems will cost between £13,000 to £15,000 and require between 38m2 to 54m2 of roof space.

However, the most accurate way to determine the cost of solar panels for your home is to find an installer. It’s important to find a reliable one that can advise you and can execute the installation smoothly. Moreover, you should always get multiple quotes to ensure you are being given a fair price. Yet how time-consuming and daunting can the searches be? Weeks can pass before you find a single quote!

Luckily, GreenMatch can do the legwork for you! Fill in the contact form and get up to 4 tailored quotes from suppliers in your area. The service is free and non-binding!

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