⚡ A 4.4kWp solar panel system typically generates 3,740kWh per year in the UK

☀️ Solar panel output varies according to multiple factors

✂️ A solar & battery system can cut your electricity bill by 103%, on average

🏖️ Solar panels produce much more energy in summer

📈 You can help to maximise your system's output

It’s widely known that solar panels generate electricity and reduce people’s reliance on the national grid, but how much electricity do they actually produce? Is it reasonable to expect solar panels to completely cover your electricity needs? 

In this article, we'll explore roughly how much electricity a solar panel system can produce, and explore the various factors that can influence solar output. 

If you’re interested in switching to solar, you can find out how much a solar & battery system could save you by answering a few quick questions below.

What’s the typical output of a solar panel system?

A solar panel system in the UK will typically generate around 85% of its peak output.

If a system has a peak rating of 4.4 kilowatts-peak (kWp), it would produce 4,400kWh per year in standard test conditions (STC), which is a set of environmental factors used across the industry to measure a panel's capabilities.

But since the average conditions in the UK are around 85% as good as STC, these panels will produce around 3,740kWh per year.

This is more than enough for the average household, which typically uses 3,400kWh of electricity per year, according to government data.

There's some variance in this figure though, which is influenced by a few different factors.

As you can see in the chart above, the main factor behind how much energy your panels generate is the size of the system, which makes sense – the bigger and better your system, the more electricity it'll produce.

But even with identically sized systems, you can see massively different output levels. Check out a few examples here:

<div style="text-align: center; font-size: 14px;">
<div style="display: inline-block; border-radius: 8px; overflow-x: scroll; max-width: 100%; margin: 40px auto; text-align: left;">
<table style="background: rgba(0,0,0,0.02);">
  <tr style="background: #4EE5D3; text-align: left; border-radius: 4px;">
    <th style="padding: 12px;">Location</th>
    <th style="padding: 12px;">System size (kWp)</th>
    <th style="padding: 12px;">Annual output (kWh)</th>
    <th style="padding: 12px;">Annual consumption (kWh)</th>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Exeter</td>
    <td style="padding: 12px;">4.3</td>
    <td style="padding: 12px;">4,665</td>
    <td style="padding: 12px;">4,750</td>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Norwich</td>
    <td style="padding: 12px;">4.3</td>
    <td style="padding: 12px;">3,767</td>
    <td style="padding: 12px;">2,401</td>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Peterborough</td>
    <td style="padding: 12px;">4.3</td>
    <td style="padding: 12px;">3,668</td>
    <td style="padding: 12px;">3,654</td>
  </tr>
  <tr>
    <td style="padding: 12px;">Wigan</td>
    <td style="padding: 12px;">4.3</td>
    <td style="padding: 12px;">3,629</td>
    <td style="padding: 12px;">3,500</td>
  </tr>
</table>
</div>
</div>

Despite all of these systems being in different places in the UK, location is not the only variable at play here.

Your system's output will also be affected by differences in roof orientation, angle, shading, and what type of inverter the system has.

🤔 Thinking of going solar? Here's why a larger system makes sense ⬇️

How much will this save you on your energy bills?

A solar & battery system will typically reduce your annual electricity bills by 103% – meaning across a year, you'll actually earn more than you spend.

This figure is based on a household experiencing average UK irradiance with a 4.4 kilowatt-peak (kWp) solar panel system and a 5.2 kilowatt-hour (kWh) battery, using 3,500kWh of electricity each year and signed up to the Intelligent Octopus Flux export tariff.

It might sound too good to be true, but technological and tariff developments have made it a reality. Households can now turn to high-performing modern solar panels and storage batteries, as well as solar export tariffs that turn your excess solar electricity into significant profits.

So your panels will dramatically reduce the amount of electricity you need to buy from the grid, and you’ll earn money by selling your excess electricity to the grid.

Octopus's export tariffs have transformed the financial benefit of solar panels, and it's easy to sign up for one – especially if you get Sunsave Plus.

How much energy do solar panels produce per day?

A 4.3kWp solar panel system will produce 10kWh per day in the UK, on average.  

However, you shouldn't take this as a hard-and-fast rule, because your system's daily generation levels will depend on a host of factors.

As well as the variables listed above – like orientation, angle, shading, and inverter type – generation will also be affected by each panel's peak output, their location, the weather, and what time of year it is, as this will determine how many hours of daylight there are.

So on average, a 4.3kWp solar panel system in London will produce 8.8kWh per day, while the same system in Exeter will typically generate 12.8kWh per day.

If it's in the ideal situation though, on a south-facing roof with an orientation of 40°, it'll produce even more solar electricity.

And wherever you are, your output will likely be around 55% below the average in winter, and 52% higher than average in summer.

As a result, you'll usually have to buy grid electricity during the colder months to make up the shortfall, but you can then sell your solar energy to the grid when summer comes round again.

At Sunsave, we have a gold membership with the Energy Performance Validation Scheme (EPVS), which means all of our savings estimates follow a methodology that has been validated by an independent third party. Whichever installer you choose, make sure their estimates are EPVS-approved!

How much energy do solar panels produce per hour?

Solar panels produce 0.4kWh per hour on average, but this includes the hours after the sun goes down, when your system won't generate any energy.

Your solar panel system will be most productive at solar noon, when the sun is at its highest point in the sky. Due to the nature of the Earth's orbit, this time is almost never exactly 12pm, but instead occurs between 11:40am and 1:10pm, depending on the time of year.

You should therefore concentrate as much of your electricity consumption as possible during this time and the couple of hours either side, to take advantage of your increased solar output. Run the dishwasher, do the laundry, cook dinner – whatever makes sense for you.

Though of course, if you have a solar battery, you can simply store the extra electricity and use it later.

The UK's first solar subscription

The average solar panel output per m² is 186kWh per year.

Solar panels are usually around 2m², which means the typical 430-watt model will produce 372kWh across a year.

A solar panel system will need space on either side, so finding out your roof's area is only one part of working out how much solar electricity you can generate, but it's a great first step.

A solar panel system does not consistently produce the same quantity of electricity throughout the year. In the summer months when the sun is high in the sky (and the days are long), solar panels are at their most productive.

And conversely, in the winter months when the sun is low in the sky (and the days are short), solar panel output drops quite significantly. 

For example, consider the below output chart, which is based on a four-bedroom home in Essex with a 6kWp solar panel system and 5kWh battery.

The system generates almost 25kWh of electricity each day in May and July, but produces just 4.9kWh per day in December. 

Broadly speaking, a solar panel system in the UK will produce about 70% of its total output in spring and summer (March to August), with the remaining 30% coming in autumn and winter (September to February). 

The chart below should give you a rough idea of how productive your solar panel system will be across the four seasons (ranging from around 11% in winter to almost 38% in summer). 

What factors affect how much energy solar panels can produce?

Solar panel power output depends on a wide range of factors, including:

Let’s explore these factors in more detail.

When it comes to solar panels, 'power' refers to the maximum amount of electricity a panel can generate (in watts). The panel's 'efficiency' is all about how effectively it can convert daylight into electricity.

Higher power and efficiency mean greater electricity production. This means that, in the exact same conditions, a 430W solar panel with 22% efficiency could generate more electricity than a 350W solar panel with 20% efficiency.

Like all electrical systems, solar panels degrade over time, which means they'll generate slightly less electricity as the years go by.

The average solar panel system in the UK loses between 1% and 3% in its first year, then around 0.5% with each subsequent year.

That means after 25 years, the average system will produce 14% less energy than it did on its first day.

Degradation is more of an issue for solar panel systems in hotter climates, where the heat can negatively affect electrical networks.

Typical solar panel degradation over 30 years

Solar panel systems are complex networks of electrical equipment that can underperform or malfunction if installed incorrectly.

If your installer doesn't secure the connections between the solar panels and inverter and the inverter and fuse box, your system may not convert DC electricity to AC electricity – which is the type your home runs on – or send all of the converted electricity to your home's devices.

And if they don't connect the diodes properly, your system could produce less solar electricity or be damaged by the battery discharging to the panels at night.

At best, bad connections will mean you get less solar electricity. At worst, a faulty connection can start a fire.

Shade can have a pretty significant impact on solar panel output, which is why it’s important to make sure there are no trees towering over your solar panel system. 

When solar panels are installed using a traditional string inverter, they’re connected in ‘strings’ (usually around 8-14 panels per string). If something is casting shade on one panel and reducing its output, this will have a detrimental effect on the electricity generation of the entire string.

This is where microinverters come in handy (more on that below).

Solar panels are built to withstand extremely hot weather, which is why there are very productive solar farms located in some of the hottest places in the world. 

However, solar panels still see a very slight drop in output once they get particularly hot - in fact, every solar panel loses a tiny sliver of generation for every degree above 25°C. On a solar panel's datasheet, this is called its temperature coefficient. 

To clarify, this coefficient refers to the temperature of the solar panel, not the temperature of the air around it.

The average temperature coefficient for a solar panel is -0.32%/°C, which means for every degree above 25°C, a solar panel's output falls by a miniscule 0.32%. 

However, even if your solar panels were to reach the dizzying heights of 50°C, they would still be operating at roughly 92% of their original capacity - not a very significant loss at all.

Typical solar panel output loss in high temperatures

Solar panels all have a hydrophobic coating, meaning they are essentially self-cleaning. When rainwater lands on a solar panel it rolls right off it, in theory taking any dust or dirt with it. 

However, in certain areas, solar panels can accumulate enough grime that it limits the amount of daylight that can hit the panels.

This phenomenon, which is known as solar panel soiling, can be brought about by detritus as diverse as dust, exhaust fumes, agricultural emissions, and organic material like bird droppings, lichen, and pollen.

In the UK, solar panel soiling can cut your system's output by more than 5%, according to Loughborough University, but it's a far more serious issue in hot, arid areas like China, India, and the Middle East, where losses can reach 70%.

Keep an eye on your solar panels, and get them cleaned every time they get noticeably dirty.

To learn more, check out our guide to solar panel cleaning. 

Never climb up on your roof to clean your solar panels (for obvious reasons)! Instead, you should get a soft, extendable brush that you can use from ground level - this will probably cost about £100. Alternatively, you can sit back and pay professionals to do it, who typically charge about £10 per panel.

As mentioned above, if one panel in a string inverter setup goes south, it'll mess up the whole string's output. With microinverters, each panel gets its own dedicated inverter and operates independently, so any malfunctions won't affect the entire system.

It’s also possible to stick to a normal string inverter and add optimisers, which are designed to improve the performance of the weakest panels in a system. 

Your system's output could also be affected by solar inverter clipping, which is when your panels produce more electricity than your inverter's peak rating. As your inverter can't process the extra energy, it'll turn into heat and be lost to you.

 Correctly sizing your inverters will avoid this happening too often, but don't spend too much in an effort to eradicate all clipping. In many cases, a small amount of clipping over the sunniest months is worth avoiding spending hundreds of pounds on more powerful inverters.

However, buying an efficient inverter is a good investment. Solar inverters are usually between 93% and 98% efficient at turning DC electricity into AC electricity, which is a large enough range to make a significant difference to your output.

The angle and direction of solar panels has a big impact on their output. Aim for the sweet spot: facing south and tilted at an angle matching your latitude. The best angle for solar panels in the UK is between 20° to 50°, depending on where you are in the country.

Solar panels can still be very effective if they’re east-facing or west-facing though – it’s just that south-facing is the optimum scenario. Any solar installer worth their salt will design a solar panel system for your property that makes the best use of your available roof space.

Whatever direction your solar panels face, some sunlight will reflect off them instead of being absorbed, reducing their output by around 2% to 4% – or it would, except more than 90% of commercial modules now come with anti-reflective coating.

The coating eliminates the great majority of this loss, so make sure it's included with any panels you buy.

You won’t be surprised to read that sunshine makes a difference to solar panel output, and the UK sees a pretty wide range of solar irradiance. In the south of England there is an average of 128.4 watts per square metre (m²), whilst in the northwest of Scotland it’s just 71.8m².  

But despite the south coast of England seeing more sunshine than anywhere else in the UK, you can still have a productive solar panel system in any part of the country. Plentiful sunshine is a bonus, but not a key ingredient – and you can see from this list just how many other factors determine how well a solar panel system works. 

Your inverter will usually contain a transformer, which performs a vital function that does unfortunately result in some energy loss.

The transformer converts incoming DC electricity to AC electricity you can use in your home, and also changes the voltage of that energy to match that of the appliances your solar energy will then power.

Unfortunately, like all electrical products, it does produce a small loss in energy – about 1%, usually – because it involves multiple complicated processes. 

Some inverters now come without transformers, which avoids this loss – but they're not common just yet.

How to ensure your solar panels produce more energy

If you’re considering having a solar panel system installed, there are a few things you do in order to maximize its output. For example: 

Your household deserves to benefit from some of the best solar panels on the market, with high efficiency rates, hefty peak power ratings, and long lifespans.

Making this choice will maximise your electricity bill savings, cut your carbon footprint by as much as possible, and help increase the value of your home.

You should only go with an installer that uses top-tier panels, both to take advantage of these benefits and because you want an installer with the good judgment and high standards to pick superior models.

This is the most important step. It doesn't matter how good your panels, battery, or inverter are if they're not properly fitted by a certified installer.

Choosing one of the best solar installers around will ensure that your installation produces as much electricity as possible, has a long lifespan, and doesn't require as much maintenance. This will maximise your savings, and also give you peace of mind.

It's worth paying a little more for a reputable, responsive, competent company that'll stick around for the aftercare, instead of leaving you to it once the panels are on your roof.

The more solar panels you get installed, the more electricity your system will produce, everything else being equal – so instead of trying to calculate how many solar panels you need, consider how many panels will fit on your roof.

Even if your system generates far more energy than your household uses, export tariffs like Intelligent Octopus Flux will pay you a high rate for all the excess electricity you send to the grid. Your profits will climb, and the national supply of electricity will get a bit greener.

It'll also future-proof your household. The UK is in the process of electrifying its transport and heating sectors, meaning electric vehicles and heat pumps are becoming commonplace.

This will result in a 50% increase in demand for electricity by 2035, according to the independent Climate Change Committee. 

If you get an EV or heat pump at any point in the coming years, you can use your 'oversized' solar panel system to run them. A heat pump will typically increase the average household's annual consumption from 3,400kWh to 6,600kWh, while an EV charger usually adds another 1,500kWh.

And even if you don't add either of these products, the rapidly rising need for electricity across the nation means the price for your exported electricity should stay high.

Microinverters can potentially increase your system's output, but they aren't always necessary – which is fortunate, since they're more expensive than standard string inverters.

If your roof comes with a significant level of unavoidable shading, you may want to use microinverters, since they allow every panel to operate independently of the others.

This avoids the major issue of using string inverters, which allow shade on one part of the system to affect every panel.

Because of the price difference though, a trustworthy installer will only recommend microinverters if it's absolutely essential.

To read more about the price of going solar, check out our guide to solar panel costs. 

Keeping an eye on your solar panel app is the best way to make sure your system's output stays high.

This is time-consuming though, and if your system's generation does fall, most solar panel owners aren't able to identify and fix the problem – and hiring an engineer can be expensive.

Fortunately, we have a solution. The UK’s first solar subscription, Sunsave Plus, comes with 20 years of remote 24/7 monitoring, meaning our solar experts will always keep an eye on your system for you.

You'll also have 20 years of maintenance support, which means we'll alert you if something isn’t working, troubleshoot any issues, and make sure your output gets back to the level it should be at.

Next steps

A solar panel's output depends on multiple factors like your location, your roof, and the quality of the system itself.

Going solar usually means covering a large chunk of your annual electricity needs and massively cutting your energy bills, but to maximise your returns, it's crucial that you choose the right installer.

Solar panel output: FAQs

How much electricity can one solar panel produce?

How much electricity will my solar panels generate?

How many solar panels do I need to produce 1,000kWh per month?

Can I run my house on solar power only in the UK?

How many kWh of electricity does a four-bedroom house use?

How much electricity do solar panels produce? [UK, 2024]

What's in this guide?

How much energy do solar panels produce?

🌞 Passing on your subscription to a new home buyer is normal in other countries

💷 You could also sell the system with your home

📈 Solar should increase your home value

“What happens if I move home during my Sunsave Plus subscription?” is a question we get asked a lot, but luckily there’s a simple answer. 

We know that you might not be in your current home for 20 years. And even if you’re planning to be, life might throw something at you that means you need to move. This is why we built Sunsave Plus to be as flexible as possible, especially when it comes to moving home.

In this article, we’ll explain why you shouldn’t worry about moving home during your Sunsave subscription and what your options are if you need to move.

Solar makes your home more attractive

Solar panels have become extremely hot property - energy bills remain a huge expense for UK households, people are much more conscious of their impact on climate change, solar technology is widely accepted, and the panels look fantastic. 

A 2023 survey of more than 2,000 UK homeowners conducted by The Eco Experts found that 69% of people are either ‘likely’ or ‘very likely’ to buy or rent a property with solar panels. In contrast, only 4% of people said they would be ‘very unlikely’ to do this.

What’s more, your Sunsave Plus subscription has additional appeal because of the Sunsave Guarantee, which means free replacement parts, 24/7 monitoring of system performance, and downtime cover. Your system will also be insured by Aviva against damage, fire and theft.

Given that electricity prices are forecast to continue rising and the UK’s electricity consumption is expected to increase as heat pumps and EVs become mainstream, it’s extremely likely that the popularity of solar panels will continue to grow. 

And solar should increase your home value

By increasing the appeal of your property, solar should also naturally boost its value.  

For the average home, solar panels increase the Energy Performance Certificate (EPC) rating by at least one grade, and homes with a higher EPC rating tend to sell for more. For instance, in research from 2023, Rightmove found that increasing a property’s EPC from a D to C lifts its value by 3% (or £11,157), on average. 

To learn more about the impact of solar on property value, check out our full article here.

We’re here to help, but you’re in control

Moving home is already stressful enough, so we’ve made the process of moving home during your Sunsave Plus subscription as simple as possible. You’ll be guided by a dedicated customer service manager who'll make sure you have everything you need and that the process goes smoothly.

Sunsave Plus doesn’t include things like an airspace or roof lease, which have historically caused issues with mortgage providers. This means you have total freedom to sell your home when you want. 

Passing on your subscription to a new home buyer is simple

In countries where solar subscriptions have taken off (such as the US and Germany), passing on the contract has proven to be very popular. For example, when customers move home, the US solar subscription provider Sunrun, sees a 98.5% success rate when transferring their contract to the new homebuyer.

To get the ball rolling, contact us in good time ahead of your home move and we’ll provide you and the new homebuyer with everything required. 

For instance, we’ll prepare all the information for your Sunsave Plus subscription, including an up-to-date proposal that shows the annual savings and export income, as well as all the relevant system documentation. 

We’ll then run a quick eligibility check on the new home buyer and provide all the information your conveyancer will need to complete the process. Then you’re ready to go.

Or you can sell the system with your home

Alternatively, you can include the value of your solar & battery system in the sale price of your home and make a full early repayment either before the sale or using the proceeds from the sale. There are no additional charges or hidden fees for this and you do not need to repay any future interest or monitoring and maintenance fees.

If you sell the system as part of the home sale process, the incoming homebuyer would have no further obligations to Sunsave. They would own the system outright and immediately start benefiting from energy bill savings. 

To learn more, check out our full guide to early repayment. 

You could take your system with you, but it might be expensive

You own your Sunsave Plus system outright from the day it’s installed, so you are free to take it with you to your new home. That said, the expense of uninstalling, moving and then reinstalling it means it’s probably not worth it. 

To move the system, you’d have to pay the scaffolding and labour costs of having it removed and transported to your new property, and then scaffolding and labour costs to have it installed again. The total expense probably wouldn’t be far off the cost of just buying a brand new system. 

However, it’s up to you, and if you do decide to take your system with you, let us know and we’ll give you a quote and ensure the process doesn’t impact your Sunsave Guarantee. 

If you pass on your Sunsave subscription, we charge a £75 administrative fee to ensure we can provide both you and the incoming homebuyer with a smooth transfer. This will only be paid on a successful transfer of the agreements and there are no other charges.

Moving home with Sunsave Plus: FAQs

How does this process work in other countries?

Do solar panels increase your property’s value?

Can you take your Sunsave Plus system with you?

Learn about your various options if you ever decide to move home during your solar subscription.

Moving home with a Sunsave Plus subscription

🏠 A roof lease gives a third party the rights to your rooftop or its airspace

➕ Sunsave Plus isn't a roof lease – it's much better

🌞 You're in full control of your panels and home

Solar products that need a roof lease come with a long list of disadvantages, and many of the solar lease companies active in the 2010s caused significant problems for consumers. 

When building the UK’s first solar subscription, we wanted to keep the consumer’s best interests at the centre of every decision, and so Sunsave Plus does not need a roof lease, meaning you’ll legally own your solar & battery system as soon as it’s installed. 

In this article, we’ll run through what a roof lease is, when it’s required, what problems it can cause, and why you don’t need to worry about any of these things with Sunsave Plus. 

What is a roof lease?

A roof (or airspace) lease is an agreement that gives a third party the rights to your rooftop, or the airspace above it, for a fixed period of time.

If you rent or lease solar panels from a third party, you will be required to sign a roof lease so that ownership of the solar panels doesn’t pass to you once they are installed. This is because in English property law, unless a roof lease is in place, ownership of the panels will automatically pass to the property owner once permanently affixed to the property.

After the government launched the Feed-in Tariffs (FiT) scheme in the early 2010s, leased solar products (known as ‘rent-a-roof schemes’) became a popular way for households to install solar panels. 

These lease models typically involved companies installing solar panels for free and acquiring the rights to the homeowner’s roof for up to 25 years. For the duration of the lease, the homeowner benefited from the electricity produced, and the company received the FiT payments.

At the end of the lease, homeowners usually had the option to either buy the solar panels, have them removed, or renew the lease.

On the surface, this product seemed great for homeowners who couldn’t afford the upfront cost of solar panels, but by giving up the rights to their roof they ended up facing a number of major problems. 

What are the issues with solar products that need a roof lease?

Many homeowners who signed solar roof leases in the 2010s have since experienced serious challenges, especially when moving home. 

And even though the situation has slightly improved, modern solar roof leases still come with notable drawbacks that should be avoided. 

You don’t have full control over your property

This is perhaps the most significant problem with solar products that need a roof lease, and the main reason that they have developed such a negative reputation since the 2010s. 

When a company owns the rights to your roof space, you lose your freedom to do whatever you’d like with your property and sacrifice one of the main advantages of home ownership in the first place.  

Some roof leases have clauses heavily weighted towards the company, which may be unfavourable to you (such as the roof lease agreement in this Which? article).

For instance, you may have to get consent if you want to make changes to your property, such as an extension, a new roof, or a loft conversion. 

Some leases may even require you to compensate the company for any missed export payments or lost electricity generation, and you could face penalties if any building work reduces the generation of your solar panels, even temporarily. 

You may face challenges selling your home 

Historically, prospective buyers have struggled to find mortgage providers willing to lend against homes with roof leases, as the roof lease could make it harder for the lender to repossess the home in a mortgage default scenario. 

Today, mortgage lenders have more awareness of roof leases and their key terms, however there is still considerable nervousness and they may require a lot of documents from you. Despite increased awareness, new homebuyers may still find they have fewer mortgage providers willing to provide a quote for the property. 

On top of this, new homebuyers may be reluctant to make an offer if they are planning to make future changes to the property.

If a company asks you to sign a roof lease, it is because they will retain ownership of the solar panels, and it will not pass to you.

We run through the key reasons Sunsave Plus is different to a roof lease, and why this matters

Charlie Clissitt

Posts from Charlie Clissitt

How much energy do solar panels produce?

Moving home with a Sunsave Plus subscription

Why Sunsave Plus does not require a roof lease

The Sunsave Guarantee explained

Sunsave Plus: what if you can afford the upfront cost of solar?

Making changes to your roof during a Sunsave Plus subscription

Sunsave Plus: a flexible way to go solar

Why you can rely on the Sunsave Guarantee

A guide to your Sunsave Plus proposal

Customer story: Tim

Customer story: Themis & Freya

Sunsave partners with Hypervolt

We’ve raised £5.4M to launch the UK’s first solar subscription

We’re a Which? Trusted Trader

Customer story: Ajith

Customer story: Fraser