4kW Solar System in the UK: Costs, Output & Pros + Cons

4kW Solar Panel System in the UK

  • 4kW solar panel systems are best for medium-sized homes with 2 – 3 bedrooms.
  • A 4kW system will produce up to 3,400kWh of energy per year.
  • It will cost approximately £5,000 – £6,000 to fit a 4kW solar system, with a return on investment of £10,500 – £11,500 and a break-even point of 8 years.

Solar panels have been popping up on rooftops across the country for a number of years, and with good reason! Solar panels produce clean, green and totally free renewable energy for our homes, but where do we begin to understand what size solar system we need? Well, if you live in a 3-4 bedroom house, a 4kW solar system is the place to start!

In this article, we will help you discover what a 4kW solar system setup looks like, how it can work alongside a solar battery and what savings you can expect. We'll also weigh up the pros and cons and help you decide if a 4kW system is right for you.

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4kW solar system with battery in the UK

The average home, with 3-4 bedrooms, usually consumes around 2,700kWh (kilowatt-hours) of electricity each year. If you are looking to power your entire home from solar power, you will need to install the right number of panels to achieve the same, or more, power than you use.

A 4kW system should be capable of achieving up to 4,000kWh in optimal conditions, but in reality, it will average approximately 3,400kWh. If you know your annual electricity consumption you will be able to best judge the size of the solar system you need.

Installing a solar storage battery alongside your solar panels can also greatly support you to run on solar power. A storage battery will allow your system to 'store' any excess energy your panels produce for you to use at a later time – it's much like charging up a reusable battery for when you need it.

How Does a 4kW Solar Panel System Work in the UK

Solar batteries are particularly useful during winters, or periods of overcast weather, as they can be a great backup when your panels slow down their energy production. To give you a better idea of how a 4kW system will work for your home, we've outlined some of the requirements and expected power outputs in the table below.

4kW Solar Panel System Requirements
Annual electricity output No. of solar panels (350W/450W) Required roof space Weight of panels
3,400kWh 8 – 10 16 – 20m2 18 – 21kg

*These figures are an estimate. Factors such as location, season and panel type can affect output and efficiency.

How much electricity does a 4kW solar system produce per day?

Solar panels are capable of powering all of your home appliances and, on super sunny days, even more! A 4kW system is likely to generate around 9.3kWh of energy each day, or approximately 3,400kWh per year. Typically a home with 2 – 3 bedrooms will use 2,700kWh each year, so a 4kW system is the most suitable size to choose. If you use more, or less than this on average, there are other options to consider.

If you know that your home uses less energy per year, you may find a smaller solar panel system more suitable. For example, a 2kW solar system is great for small homes with 1 – 2 bedrooms with energy use of up to 1,700kWh.

If it's more energy you need, however, a 5kW solar system will generate around 4,250kWh. If your home is slightly larger, or you have a very high electricity usage per year, you might need a 6kW solar system, which can offer 5,100kWh.

Energy Produced From 4kW Solar Panel System*
Per day Per month Per year
9.3kWh 279kWh 3,400kWh

*These figures are an estimate. Factors such as location, season and panel type can affect output and efficiency.

4kW solar system with battery costs

One of the biggest concerns when considering solar panels is, how much will they cost? It's important to know all of the prices that are involved so that you can be certain that they fit within your budget.

There are different aspects to consider, such as installation fees, labour costs and any ongoing maintenance needs. In addition, if you wish to add one, you will also need to account for the cost of a solar storage battery, which can be up to £10,000+ depending on the size you choose.

To help you get an idea of the costs involved, we've outlined the prices you can expect to pay for each element of a 4kW solar system in the table below.

Costs for a 4kW Solar Panel System
Solar Panel System (inc. installation) £5,000 – £6,000
Solar battery costs (9 – 10kWh*) £8,000 – £9,500
Labour costs £600 - £1,000
Annual service £100 – £200

*Recommended size for a 4kW solar panel system. Please note the above prices are a guide only and may vary depending on your circumstances.

The cost of a 4kW solar panel system may seem expensive upfront, but there are opportunities to lower these costs through Government grants or incentives. We've detailed some of the main schemes below that can help with associated costs.

  1. Smart Export Guarantee (SEG)
    The Smart Export Guarantee requires energy suppliers to pay homeowners for any surplus solar-generated electricity they export back into the national grid. This works on a tariff basis and can provide additional income to help offset the costs of solar panel installation.Tariff rates vary between energy suppliers, but could be between 1p – 40p per kWh (bear in mind these tariffs frequently change). This means a household with a 3-6kW solar panel system could earn anything up to £400 per year through SEG payments. You can secure higher payments by installing a solar battery to store the excess electricity you generate.
  2. Energy Company Obligation 4 (ECO4) Scheme
    This scheme was created to support low-income households across England, Scotland and Wales to access energy efficiency upgrades – for some eligible households, this can include free solar panels. The ECO4 scheme is run through local authorities and energy suppliers, and strict criteria do apply. The scheme will run until March 2026.
  3. 0% VAT
    In 2022, the UK Government reduced VAT to 0% for a range of energy-saving products. This includes solar panels and solar batteries in order to make energy-efficiency measures more affordable. This means that you could save up to £1,850 on installation costs until March 2027.
  4. Home Energy Scotland
    Residents in Scotland can benefit from different support offered by Home Energy Scotland. This can be either as a funding grant or an interest-free loan to cover the installation of renewable technologies, including solar panel systems. Up to £6,000 is available, with £1,250 as a grant and an optional loan of £4,750. Set eligibility criteria do apply.

Depending on where you live, you may have access to location-specific grants, so it is worth checking with your local authority to see if there are any other schemes you could benefit from. Schemes such as these can provide significant funding to help alleviate the cost of installing solar panels.

How much can you save with a 4kW solar panel system?

Solar panel systems are a great way to produce your own, renewable energy to power your home and free yourself from high energy prices – but before installing a new system you might be wondering how much you can save with a 4kW solar panel system?

For a 4kW set-up, which costs approximately £5,000 – £6,000, you can expect a return on your investment after 8 years. With the average lifespan of solar panels at 25 – 30 years, you can expect to enjoy the savings they can provide quite early into their life cycle.

Your overall savings potential will largely depend on your energy consumption and whether you take advantage of the Smart Export Guarantee, or install a solar battery. Based on a medium-sized home which uses an average of 2,700kWh per year, we've outlined some expected savings below.

4kW Solar Panel System Savings Estimates
Annual savings £660
Savings after 25 years £16,500
Break even point 8 Years
Annual savings with SEG payments* £700
Return on investment (ROI) after 25 years £10,500 – £11,500

Annual savings are calculated by multiplying the average energy consumption by current electricity rates. Prices are taken from the latest tariffs in Jan-March 2024. *Using an example SEG tariff of 5.5p.

With the potential to save hundreds of pounds every year with solar panels, you might be keen to get started with installing a 4kW solar panel system, but not sure where to start? It's always best to get several quotes for your work and compare them, but tracking down trusted installers can be an overwhelming task.

Avoid the pain of spending hours endlessly scrolling the web, reading customer reviews and sending multiple messages hoping to hear back. Instead, just fill in our one simple form and wait for the quotes to come to you!

With a trusted network of solar installers, we can connect you with up to 4 local professionals from your local area. They will provide you with free, bespoke quotes for you to compare with absolutely no obligation.

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Pros and cons of a 4kW solar system in the UK

When considering a large home investment, it's good to understand the full scope of advantages and disadvantages. To help you clearly weigh the pros and cons, we've listed some of the most important points to consider.

4kW Solar System in the UK_Pros and Cons


  • Energy cost savings: A typical 4kW solar system in the UK can generate about 3,400kWh per year. This can save an average household up to £660 a year on their electricity bills, with additional savings available through the SEG incentive.
  • Reduced environmental impact: Solar panel systems can greatly reduce your carbon emissions (a typical home could save up to 1 tonne in carbon per year). This is because they can replace your dependence on grid energy which is still largely produced through fossil fuels.
  • Financial protection: A 4kW solar panel system will give you an independent energy source, freeing you from fluctuating energy prices associated with major energy suppliers.
  • Low maintenance: Solar panels need very little maintenance, aside from occasional cleaning and possible services which are typically under £100 a year.
  • Increased property value: Due to the increased desire for renewable home systems, some research suggests solar panels can increase a property's value by 4% – 14%.


  • Upfront costs: A 4kW solar panel system can cost between £5,000 – £6,000 which is a considerable investment for most homeowners. If you are not eligible for any grant or funding support, this can be a more significant hurdle to overcome.
  • Roof space: Depending on the style and size of your roof, it may not be possible to install a system large enough to power your entire home. A 4kW solar system requires 16 – 30m2.
  • Appearance: Some homeowners do not like the visual appearance of some solar panels materials which could limit the choices you have and impact costs. In addition, if you live in a conservation area, or a protected building, you may require permissions to install certain technologies, further limiting your options.
  • Weather dependent: Solar energy output largely depends on weather conditions. In the UK we have plenty of sunlight hours for solar panels to produce enough energy to power our homes. If, however, you wish to power your home during the night, or your roof does not get enough direct sunlight, you will need to store your solar energy in a solar battery. These can cost up to £9,500 for a 4kW system.

Is a 4kW solar system worth it?

For those looking to save money and improve their environmental impact, the answer is a firm yes! A 4kW solar panel system has many benefits for a medium-sized home. It can reduce your energy bills, give you greater financial freedom from price rises, and greatly reduce your carbon emissions.

There are, however, some big considerations, such as the upfront installation costs and whether you want a solar battery. Having a solar battery allows you to use solar energy at night and gives you a greater opportunity to make additional income through SEG payments. It will, however, increase your initial costs.

The great news is, however, that a 4kW solar panel system will give you a return on investment of between £10,500 – £11,500, and you can break even on upfront costs in just 8 years. This is thanks to an annual savings potential of up £660 – £700.

If you're ready to benefit from solar energy it's important to find the right price for your budget. We recommend speaking with multiple solar installers and getting several quotes so that you can compare prices and get the best deal for your needs.

It can be a dull and daunting task that can take up hours of your spare time, but luckily we offer a quick and simple alternative! By filling in our form, we can connect you with up to 4 solar installers in your local area, from our network of trusted professionals. They can provide advice and free, no-obligation, quotes for you to compare!

Get started today by clicking the button below.

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Frequently asked questions

How much power will a 4kW solar system produce?
A 4kW solar panel system can produce approximately 9.3kWh of electricity per day, or 279kWh per month. A 3-4 bedroom house typically uses 2,700kWh annually, making a 4kW system ideal as it can produce 3,400kWh per year.

What can a 4kW solar system run?
A 4kW solar system is powerful enough to supply energy to all of your home appliances if you live in a 3-4 bedroom property. To understand if a solar panel system can run your property, it's best to check your average energy consumption in kilowatt-hours (kWh) to compare output.

How many batteries do you need for a 4kW solar system?
This will be determined by your house size, average energy usage and typical excess energy production. On average, a 4kW solar panel system will need a 9-10kWh battery, these solar battery costs can be up to £9,500.

How many solar panels are in a 4kW solar system?
You can expect to install between 8 – 10 solar panels for a 4kW solar panel system. You can save money on your 4kW system by comparing different solar panel materials. The exact number of panels will depend on the wattage of each panel and the amount of roof space you have.

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