4kW Solar Panel System Guide And Costs

DISCLAIMER: Our partners no longer take appointments for homeowners looking to benefit from the Feed-in Tariff, which is due to end on 31st March 2019

A typical 4kW solar panel system will generate savings of up to £6,850 over 20 years and cost around £6,000. That’s a return on investment of almost £1,000.

A 4kW system is the most popular size for residential solar panels and will deliver a healthy return on your investment.

You can get a personalised 4kW solar panel system quote for your home by completing the form at the top of this page.

In This Guide to 4kW Solar Panel Systems:

4kW Solar PV Systems

what is a 4kw solar pv system

4kW solar systems are one of the most popular sizes of residential solar in the UK. They typically produce approximately 3,400kWh of electricity per year - that’s enough to cover the energy usage of a family home of 4 people! 4kW solar systems last approximately 25 years before they need replacing.

4kW solar systems are comprised of 16 solar panels, and typically require about 24 to 28 square metres of roof space to be installed. If you have limited roof space however, it is possible to get a high efficiency 4kW system that takes up less room. 4kW solar systems installed on a south, east or west facing roof with little or no shade will work to the highest efficiency.

4kW solar systems will produce more energy when there is more sunshine, yet they will generate you plenty of free electricity all year round. This makes them a sound investment for anyone looking to save money and become more eco-friendly.

Back to top

How Much Does a 4kW Solar Panel System Cost?

The table below shows the typical price of a 4kW solar system (including 5% VAT) compared to other residential sizes:

Typical Solar System Size:
Number of Solar Panels:
Roof Space:
Estimated Cost:
8 sq. metres
£1,500 to £3,000
14 sq. metres
£3,000 to £5,000
21 sq. metres
£5,000 to £6,000
28 sq. metres
£6,000 to £8,000

If you cannot finance the cost of your 4kW solar system yourself, some solar companies offer low interest loans on solar panels. These companies will pay the upfront cost of purchasing and installing your 4kW solar system, and will then ask you to pay back the money you owe at a fixed interest rate over several years.

Learn more about solar panel costs

How much could you save with Solar Panels? What's your average monthly electricity bill?

How Much Can You Make With a 4kW System?

DISCLAIMER: Our partners no longer take appointments for homeowners looking to benefit from the Feed-in Tariff, which is due to end on 31st March 2019

How Will You Earn and Save Money?

Installing a 4kW solar system onto your home allows you to earn money from the UK government’s Feed-in Tariff scheme and to save money on your electricity bills:

Generation Tariff: your energy provider will pay you a fixed rate for every kWh of electricity you produce from your solar system. You will start to receive these payments once your solar system has been registered, and the tariff rate will be guaranteed for a period of 20 years.

Export Tariff: your energy provider will also pay you a fixed rate for each kWh of electricity that you don’t use and sell back to the national grid. Until smart meters are installed to accurately monitor how much electricity you give back to the grid, energy suppliers currently estimate that households with a 4kW solar system export approximately 50% of the electricity that they produce. You will start to receive these payments once your solar system has been registered, and the tariff rate will be guaranteed for a period of 20 years.

Energy Bill Savings: as you are producing free electricity from your solar system, you can save up to 50% on your energy bills every month. This is because you will not have to buy as much electricity from your energy provider to power the appliances within your home. The exact amount you will save will depend on how much energy you use.

What is the Current Feed-in Tariff Rate for a 4kW Solar System?

The table below shows you how much you could earn from each kWh of electricity you produce from your 4kW solar system, based on the Feed-in Tariff rates for October to December 2018:


Date Range:

Generation Tariff for 4kW Solar System:

Export Tariff for 4kW Solar System:

Q4 2018
Oct 1st to Dec 31st
3.86p per kWh
5.24p per kWh

The Feed-in Tariff rates get reduced every quarter. If you are considering solar panels don’t wait too long as you will want to qualify for the current higher Feed-in Tariff rates. Once you register your panels, you are locked in at those rates for the entire 20 years of the Feed-in Tariff.

Please be aware that for homeowners in England, Scotland and Wales, you will need to prove that your house has an EPC rating of band D or above to receive these Feed-in Tariff rates. If your house has an EPC rating of E to G, you will qualify for lower generation and export tariff rates.

An EPC rating tells you how energy efficient a building is, and it spans from A (very efficient) to G (very inefficient). You will need to provide your home’s EPC rating when you apply for the Feed-in Tariff.

Click here to learn more

How Much Will You Earn?

The table below shows you the typical earnings from a 4kW solar system in different cities in the UK. These earnings are estimates and are based on the Feed-in Tariff rates for systems installed between October and December 2018:

Annual Payment from Generation Tariff
Annual Payment from Export Tariff
Annual Electricity Bill Savings
Total Earnings in the First Year
Profit over 20 Years

*based on a £6,000 4kW solar system installed on a south facing roof with no shade and a monthly household electricity bill of £50

Please note that for homeowners in Northern Ireland, the Northern Ireland Renewables Obligation Certificates (NICROS) scheme ended in April 2017. This means that you can no longer receive payments from the generation tariff for the electricity you produce from your solar panels. You can however, still cut your monthly electricity bills and receive payments from the export tariff for the electricity that you sell back to the national grid.

Back to top

Get a Bespoke 4kW Solar Panel System Quote for Your Home

Is a 4kW System Right for You?

There are 4 factors you should consider when deciding whether to install a 4kW solar system:

1. You want a high return on your investment

You can earn over £300 each year and turn a profit of £1,280 over 20 years by installing a 4kW solar system onto your home. This makes it a sensible investment with a guaranteed income over a prolonged period of time.

2. You have enough roof space

A 4kW solar system requires approximately 24 to 28 square metres of roof space to install. Your roof also needs to be in little to no shade and ideally south-facing for your solar system to be efficient.

3. You use a moderate amount of electricity

A 4kW solar system produces around 3,400kWh of electricity each year. This is typically enough energy to power a household of 4 people. You should review your monthly electricity bills to determine your annual electricity needs.

4. You want to reduce your carbon footprint

You can save a staggering 40 tonnes of carbon dioxide over 25 years by installing a 4kW solar system. Investing in this renewable energy is a great way for you to become more eco-friendly and build a more sustainable future.

4kW solar system roof space

Back to top

Installing a 4kW Solar System

Here are some key points to remember when installing a 4kW solar panel system:

  • You will typically need 24 to 28 square meters of free roof space. This roof space will need to be shade free for the majority of the day to get the best results.

  • Your 4kW solar system will be most efficient if it is installed on a south, south-west or south-east facing roof. West and east facing roofs are also suitable, but will generate around 15% less electricity.

  • You will also need a small amount of space (normally in the loft) for your inverter. This converts the sun’s light into the electricity you use, whilst also monitoring the amount of energy your 4kW solar system generates.

  • Before your installer installs your 4kW solar system, they are required to complete a survey of your roof structure to ensure it is suitable for solar panels. Most roofs in the UK can support the weight of solar panels, but installers are legally obliged to check. If your roof is old, it is advisable to have it re-roofed before installing a 4kW solar system.

  • To qualify for the UK government's Feed-in Tariff scheme you will need to use an MCS accredited installer to install your 4kW solar system. You will be issued with an MCS certificate once your installer has registered your solar panels on the MCS database.
92% of homeowners we surveyed rated their solar panel installation as good to excellent*

*Based on a survey we conducted in January 2018 of 390 UK homeowners with solar panels.

Once your 4kW solar system has been installed, it requires very little maintenance work. You should try to keep your solar panels clean and prevent any foliage from shrouding them in shade, however. Doing this will ensure that they work to their optimum efficiency.

Your installer should provide you with written instructions about how to carry out regular maintenance checks on your 4kW system to keep it working properly. Monitoring how much electricity your solar panels produce on a daily basis should help you to identify if there are any problems.

Your 4kW solar system should last around 25 years before it needs replacing. Your inverter may need replacing within this time however, at a cost of roughly £750.

Back to top

Finding the Best Price

It is recommended that you compare quotes from at least 3 or 4 MCS accredited installers to ensure you get the best price. Always ensure that the quote breaks down the different elements of the total cost.

You can join the thousands of homeowners who have used The Eco Experts to get a 4kW solar system quote. Simply enter your postcode at the top of this page to begin.

How Much Will a 4kW Solar Panel System Cost You?

Spread the Word!