When you’re buying a solar panel system, you want to ensure you’re getting the correct size for your household.

A 5kW solar panel system is usually a safe choice for a four-bedroom property, but this depends on factors like your present and future energy usage and the solar battery you pick.

In this guide, we’ll explain what a 5kW solar panel system is, how much it costs, and which devices it can power over an average day.

If you’re wondering how much a solar & battery system could save you, just answer a few quick questions below and we'll generate an estimate for you.

What is a 5kW solar panel system?

A 5kW solar panel system has a peak output rating of five kilowatts, meaning it produces 5,000 kilowatt-hours (kWh) of electricity per year in standard test conditions.

You can construct a 5kW system by acquiring solar panels with power ratings that add up to 5,000 watts (W) when grouped together – for example, 12 panels that are all rated at 430W.

This doesn’t necessarily mean your system will generate 5,000kWh, since solar panel output is affected by factors including your location, roof angle and direction, and the quality of the installation.

You might also see a 5kW system referred to as a 5kWp (kilowatt peak) system. In this context, both phrases have the same meaning.

How many solar panels are in a 5 kW system?

There are 12 solar panels in a 5kW system, if you buy 430W panels.

How many solar panels you’ll need in order to install a 5kW system will totally depend on your panels’ peak power ratings, though.

For example, if your installer only has 350W solar panels in stock, you’ll need 14 panels.

Purchasing panels with higher peak output ratings can reduce the number of panels you need, which is a good solution for households with limited roof space.

What size battery should you add to a 5kW system?

You should generally add a 5-7kWh battery to a 5kW solar panel system.

This enables you to store your excess solar electricity all year round, to use when skies are grey and after the sun sets.

You’ll power your home with more of the abundant energy your solar panels produce in spring and summer, and squeeze every last drop out of the electricity they generate in autumn and winter, minimising wasted energy in the process. 

The size of battery you should get will depend on multiple factors though, including how much electricity your household consumes per day, and the shape of your annual usage pattern.

If you have an electric vehicle and charger, for example, and take more trips in the summer, you may use more solar electricity in those hotter months than during winter – which may mean there’s no need for a larger battery.

However, a bigger battery might be a good idea if the people in your household spend most of their time outside of the home while the sun’s up – for instance at school or work – since you won’t be able to use the majority of the solar electricity as your panels produce it.

What size inverter should you add to a 5kW system?

A 5 kW system generally needs a 3.5kW inverter, since your solar panel system should be roughly 50% bigger than your inverter, as a rule of thumb.

This is largely because in most UK locations, your solar panels won’t often reach their peak power rating, since our weather usually fails to meet standard test conditions.

Standard test conditions include a solar irradiance of 1,000 W per m² and a cell temperature of 25°C, and is the way manufacturers measure a solar panel’s output.

The electricity generated by a 5kW system in the UK can still save you hundreds of pounds per year, but you won’t produce much beyond 5,000kWh per year, even in the sunniest regions.

And it’s a better idea to choose an inverter size that matches your system’s actual output, instead of its idealised levels.

An inverter – like any electrical item – needs power to function, called its 'startup voltage'. It should always be at this level, at least, meaning that undersizing the inverter is also safer.

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How much does a 5kW solar panel system cost?

A 5kW solar panel system costs around £11,500 to buy and install.

If you want to add a battery to this system, it’ll push the price up by around £2,000, for a total cost of £13,500.

This final cost can vary substantially though, based on factors including where you live, the type of roof you have, the installer you choose, and the current state of the industry.

If you want to learn more, check out our full guide to solar panel costs.

How much energy will a 5kW solar panel system generate?

A 5kW solar panel system will generate 4,250kWh of electricity per year in the UK, on average.

This means you’ll typically produce roughly 85% of your system’s peak power output.

We’ve based this figure on a household experiencing average UK irradiance that has a 4.4kWp solar panel system and a 5.2kWh battery, uses 3,500kWh of electricity per year, and is signed up to the Intelligent Octopus Flux export tariff.

A solar panel system will usually generate less solar electricity in areas with lower amounts of sunshine, such as Scotland or northern England, or more if you live in a sunnier place like Cornwall, Devon, Dorset, Essex, or Sussex.

For example, a 5.2kW system we designed for a Bedfordshire household has an estimated annual output of 4,763kWh, and our design for a 5.6kW array in Suffolk would have produced approximately 5,894kWh per year.

However, another of our 5.2kW designs, for a property in Cumbria, would generate roughly 3,829kWh per year.

What can a 5kW solar panel system run?

A 5kW solar panel system can run the average four-bedroom household, on a typical day.

It can generate 11.6kWh of solar electricity per day, on average.

This amount of electricity can power all of the devices below for the stated amount of time, according to Centre for Sustainable Energy data – with some extra energy left over.

Is a 5kW solar panel system big enough?

A 5kW solar panel system is big enough if it approximately matches your annual electricity consumption.

But you should always consider getting as large a solar panel system as your roof allows, if you can afford it.

The fixed prices of labour and scaffolding typically make up a large proportion of your costs, so adding more panels doesn’t raise the overall price by much, which means it makes financial sense to fill up your roof – unless it’d mean extra scaffolding.

Choosing a bigger system and one of the best export tariffs will help you to cut your electricity bills by even more – and could prepare your household for any future increases in your usage.

If you’re considering getting a heat pump, buying an electric car, or welcoming a new addition to your family at some point, a larger solar panel system can help you lessen the impact.

It’ll cost you more to add to your solar panel system at a later date, as you’ll have to pay the additional costs – like scaffolding – all over again, so it pays to plan ahead.

How much space do you need for a 5kW solar panel system?

You’ll typically need 37.8 square metres of roof space for a 5kW solar panel system.

This total takes into account the average height and width of a solar panel – around two square metres – plus the extra spaces installers generally leave.

Your solar installer will usually make sure there’s a 40cm space between the panels and your roof’s sides, and a 3cm gap between each panel, to follow Microgeneration Certification Scheme (MCS) guidelines.

If you have a vent pipe, chimney, or skylight (also known as a Velux window), you’ll require more roof space – but not much.

If you have all three, you’ll usually need another 0.81m², for a total of 38.6m².

Is a 5kW solar panel system worth it?

A 5kW solar panel system is definitely worth it, so long as it’s correctly sized for your household.

If it is, it’ll benefit you in multiple ways. You’ll cut your electricity bills by up to 103%* if you use a smart export tariff, which enables you to get paid for the excess solar electricity you send to the grid.

You’ll also shrink your carbon footprint by around a tonne of CO2 per year on average, according to our calculations, and reduce your reliance on the grid, which can help lessen the impact of energy price cap rises.

Across 25 years of enjoying all these advantages, the average owner of a 5kW solar panel system can expect to have made tens of thousands of pounds in savings.

And a 5kW system will almost always boost your Energy Performance Certificate rating by a grade, which typically results in a 3% increase in your home’s value, according to Rightmove’s 2023 study of 300,000 properties.

If your home costs £285,000, which is the UK average as of February 2024, a solar panel system will typically raise its value by £8,550.

* This figure is based on a household experiencing average UK irradiance that has a 4.4kWp solar panel system and a 5.2kWh battery, uses 3,500kWh of electricity per year, and is signed up to the Intelligent Octopus Flux export tariff.

Do you need planning permission for a 5kW solar panel system?

You don’t generally need planning permission to install solar panels on a home, including 5kW systems.

Domestic solar installations are almost always protected by permitted development rights, which enable homeowners to carry out medium-sized improvements without planning permission.

You’ll usually only have to apply for permission if you live in a flat, listed building, or conservation area – or if you want to install a ground-mounted system.

However, your installer will need to send a G99 application to your area’s Distribution Network Operator (DNO) if your inverter’s maximum capacity is more than 3.68kW on a single-phase system.

This is sometimes the case with a 5kW installation, as your solar panel system should be around 50% bigger than your inverter – which would lead to a roughly 3.5kW inverter – and some installers prefer to fit a larger inverter.

If it is required, a G99 application should be a simple formality that makes your DNO aware of your system, so it can take the extra electricity into account while running its part of the grid.

Can you get an off-grid 5kW solar panel system?

You can certainly get an off-grid 5kW solar panel system installed, and in most scenarios, it’ll provide a large proportion of the electricity you need.

Since you can’t export excess energy to the grid, your focus will be on buying a large battery to store as much electricity as you can.

A 10-12kWh battery will likely meet your needs, depending on where you’re living and your electricity usage.

You may also want to add other sources of renewable energy alongside your solar panel system, like a wind turbine.

A 5kW solar panel system will only provide you with enough electricity to live off-grid if you can be careful with your consumption and use significantly less energy in winter.

Summary

A 5kW solar panel system can massively reduce your electricity bills, and is suitable for the average four-bedroom household.

However, most homes don’t align with the average, so make sure the size of your system is based on your current and future electricity consumption, rather than averages.

The best way to find out the right solar panel system size for your home is to hire a company with the relevant expertise, abilities, and accreditations – like Sunsave.

If you’re interested in how much you could save with a solar & battery system, click the button below, enter a few details, and we’ll generate a quick estimate.

5kW solar panel system: FAQs