☀️ Solar panels convert sunlight into electricity to power your home

📈 Solar panel efficiency is continually improving

Solar panels are a green and cost-effective way to harness the power of the sun to create an energy source for your home. And if you can't pay the high upfront cost of solar panels, you can get solar panels at no upfront cost via Sunsave Plus. 

Most people are familiar with the fact that solar panels generate electricity, but far fewer people know quite how they do it. The process is a fascinating bit of science, and has pretty rapidly become one of humanity’s tools for slowing down climate change. In this article, we’ll run through the basics of how solar panels work, so by the end you’ll be able to tell your photons from your electrons.

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

The way a solar panel converts daylight to electricity happens in five simple steps. 

During the day, we get solar radiation from the sun. Within this solar radiation are individual particles of light called photons. 

Solar panels are positioned for maximum exposure 

Each solar panel is positioned to make sure that it gets as much exposure to daylight as possible. This is typically on rooftops and in fields.


When photons make contact with solar panels, they meet solar cells. These cells are made of silicon, but are split into two layers, each with a different element: one with phosphorus and one with boron. The phosphorus gives the top layer lots of electrons (i.e. a negative charge), whilst the boron ensures the bottom layer has far fewer elections (i.e. a positive charge). This creates an electric field between the two layers of silicon.

When a photon hits the solar cell, it knocks an electron free and an electric charge is created. Once the loose electron enters the electric field between the two silicon layers, it’s pushed out and sent on its way. 

Electricity is converted from DC to AC – and sent into your home

Solar cells create direct current, or DC, where electrons flow in a single direction. However, it’s difficult to transmit DC over any kind of distance, so most households use alternating current (AC) instead. A solar inverter transforms the current from DC to AC, so it can be used directly to power your house. 

Solar panels are powered by light, not heat, so as long as there is daylight they will work. The only type of weather where they absolutely won’t work is when heavy snow has settled on the panel. 

Having said that, solar panels do tend to be less effective in winter, due to shorter days and less daylight. Cloudy days may also mean less sunlight can get through. But the good news is that rain will actually clean your panels. 

The only other thing to bear in mind is that while direct sunlight is obviously a good thing, getting too hot can actually make your panels less productive – for every degree above 25°C, solar panels become marginally less efficient. 

Should the temperature reach 65°C then there is a danger that solar panels will stop functioning entirely, but this is of course rather unlikely to happen in the UK.

When you’re looking to invest in solar panels you’ll notice that efficiency is a key metric. Efficiency means the percentage of sunlight that hits the panel that is then converted into electricity. The efficiency rate will impact how much money you will be able to save in the long run. 

Currently, solar panels can’t convert each and every wavelength of the sun’s light, and so you’re likely to see efficiency rates of between 15% and 22%, although a small number of very premium solar panels are able to achieve rates of 23% and above. 

There is also a new type of solar panel made from perovskite solar cells which has achieved over 33% efficiency in lab tests, however this isn’t yet commercially available. 

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

Solar panel technology is advancing all the time, and, as more people start using them, the speed with which it progresses is getting even faster. 

Scientists around the world are working to develop solar panels that will be able to capture even more of the sun’s light waves. In the lead is NASA, which is currently developing solar cells with a 40% efficiency rate. 

Another technology to look out for is perovskite, a relatively new technology which allows panels to absorb the red end of the spectrum, increasing efficiency to as much as 33%. It’s hoped these will be available commercially in 2024.

Solar panels work very well in space, the difficulty is just getting the electricity back to Earth. Since there is no atmosphere in space, the sun’s light is undiluted - and solar panels can generate up to twice the amount of energy as they do on Earth. For that reason, they are often used to power spacecraft and satellites.

However, while some people, such as astronaut Tim Peake, suggest we create solar farms in space, finding a cost-effective way of transferring that energy to Earth remains a challenge.

Generally, solar panels (in the northern hemisphere) perform best when they are south facing, but there are other factors that can help, such as hours of sunlight in a day, and the availability of usable land.

In 2022, the World Bank identified the areas with the most potential as Southern Africa –and Namibia in particular – North Africa, the Middle East, South America and Australia.

Do all types of solar panels work the same?

The most common types of solar panels are made up of monocrystalline or polycrystalline. They work in a very similar way, generating electricity through a combination of silicon, boron and phosphorus. 

But there are other panels that use different kinds of processes – many of which are still in development. These include: 

Scientists have taken the natural mineral perovskite and combined it with inorganic material to create perovskite semiconductors. This material is different to traditional silicon, in that it’s able to absorb a greater spectrum of light. That’s what gives perovskite solar panels dramatically higher efficiency than regular solar panels.

Quantum dots are small particles undetectable by the human eye that reverse the way electrons move. This means they are able to capture energy from light that would otherwise be lost.

These work similarly to traditional solar panels, and structurally the only real change is instead of using crystalline they have a very thin layer of carbon-based organic materials, resulting in a material that is more flexible but currently less efficient.

These are cells containing copper-based electrolytes that have dried out – which is why they’re called Zombies. Surprisingly, it means they are better able to absorb different kinds of light, including artificial light. 

Do black solar panels work better than blue solar panels?

In the vast majority of cases, black solar panels work a lot better than blue solar panels.

Blue panels are made of polycrystalline so they are more affordable and create less waste in the production process. 

Black panels, on the other hand, are made of monocrystalline. This means they can absorb light more efficiently, meaning you need fewer of them in order to generate the same amount of power, so they use less roof space.  They also tend to last longer, with higher heat resistance and an average warranty of 25 years.

How do solar panels work step by step? 

How many solar panels does it take to power a house?

How do solar panels work with your electric bill?

How do solar panels work? | 5 steps explained

How do solar panels work?

☀️ Solar panels work well all over the UK, but sunny weather improves output

📊 Met Office data reveals the average hours of sunlight per year between 1991-2020

🌊 Most of the UK’s sunniest spots are on the south coast 

Let’s start by busting the myth that solar panels need sunlight. 

You don’t need sunny weather for solar panels to work effectively. Solar panels need daylight - not sunlight - in order to produce electricity, which means even on overcast days they still generate power. 

There are in fact many aspects that affect the output of a solar panel system, including roof orientation, angle, shading, panel efficiency, panel power, bird mess, the list goes on. You will find many solar panel systems all over the UK that work well and significantly reduce electricity bills. 

However, it’s no secret that sunshine still has a big part to play when it comes to solar panel output. We’ve put together a list of the top 11 sunniest spots in the UK based on Met Office data from 1990-2020 - places where solar panels will make serious hay whilst the sun shines.

If you’re interested, you can find our methodology at the bottom of the article. And if you're interested in making the switch to solar, check out our guide to solar panel costs. 

Bournemouth didn’t quite make it above the 1,800-hour mark, but still towers above most other towns in the UK when it comes to quantity of sunshine. It’s the busiest place on the list, with a population of nearly 200,000.

The town has a consistent, coastal microclimate, with very hot summers and not particularly cold winters (it rarely drops below zero). Unsurprisingly, the town's seven miles of sandy beaches are hugely popular all year round, and it was here that the UK’s very first beach hut was built in 1909. 

As a picturesque spot on the Jurassic Coast, Swanage enjoys more than 1,800 hours of sunshine every year. Its bay offers sheltered, sandy beaches, and is a well known tourist destination. Also popular is neighbouring Corfe Castle, a ruined castle which dates back to William the Conqueror. 

The area is also famous for the stone that is quarried here, including the famous Purbeck marble, with colours ranging from blue and green to grey, which has been prized since Roman times. Swanage is home to just over 9,000 people.

Probably the strangest name on the list, Walton-on-the-Naze is a seaside town on the Essex coast of the North Sea. It notches up an average of 1,824 hours of sunshine each year and has a pretty tiny population of just 7,000. 

The place has a pretty weird history. Walton used to be an inland village that has ended up by the sea due to coastal erosion, and ‘the Naze’ it sits on is actually a peninsula famed for its wildlife. If you fancy looking for very old shark teeth, the Naze is your place to go. 

The Manston climate station is just three miles away from Ramsgate, and it has recorded an average of 1,846 hours of sunshine a year between 1990 and 2020. 

Situated on England’s south coast and looking directly across to Calais and Dunkirk, Ramsgate is famed for its stunning bay and sandy beach. And there are 42,000 people who call it home. 

Like many of the country’s sunniest spots, Ramsgate enjoys a regal connection: George IV was so impressed by the treatment he received here he decreed it the only royal harbour in the UK. 

The climate station for Southend-on-Sea is located in the intriguingly named suburb of Shoeburyness. And it is here that the Met Office has recorded an average of 1,884 hours of sunshine a year. 

Located on the Thames estuary and with a population of more than 183,000, Southend-on-Sea is also known for its tourist attractions, including the world’s longest pleasure pier. Stretching for 1.33 miles, the pier offers fishing and wildlife watching, and even has its own train.  

One of several towns on the list with its own microclimate, Eastbourne is wedged between the South Downs and the sea, giving it some fairly consistent dry and warm weather. It sees 1,892 hours of sunshine each year, which is nearly 500 hours more than the UK average, and is home to almost 104,000 people.

Eastbourne has long been a popular day trip from London, and is famed for its sandy beaches, picturesque Victorian architecture, and pier. It’s also only a short distance from Beachy Head, the highest chalk cliff in England.

But there’s also evidence that Eastbourne was popular even before the Victorians made their mark, with remains found dating back to the Stone Age and the Romans.

Located halfway along the Jurassic Coast, the Dorset town of Weymouth is a big tourist destination for people in southern England. It sees just over 1,900 hours of sunshine each year, and there are more than 55,000 people living there. The port has been a historic gateway for centuries, whether it was the Romans shipping in supplies, or people heading for America in the 19th century. 

It’s also been popular with the royals, of course, with George III setting up his famous bathing machines in the 1700s. Visitors today still flock to Weymouth’s sandy beach dotted with brightly-coloured beach huts.  

Hastings is probably one of the most famous coastal towns in the UK (for battle-related reasons), and whilst its historic fishing industry has waned, its great potential for solar power has not. There are nearly 93,000 people who call Hastings home, and if they ever tire of the history lessons they can always turn to the sea for entertainment. 

The town is a place for proper, old-fashioned seaside fun, as well as some old castle ruins, and a blossoming arts scene.

Edging slightly ahead of Hastings is Bognor Regis, which sees 1,919 hours of sunshine each year. This seaside resort was once just known as Bognor, until it got special approval from King George V in 1929 and was given the second name ‘Regis’ (which means ‘of the king’). 

With a population of over 68,000, the town is located between the South Downs and the sea, which gives it a rather dry and warm microclimate.

The climate station at Folkestone ski station, three miles outside the historic port town, has recorded an average of 1,932 hours of sunshine a year between 1990 and 2020 - making it the UK’s mainland sunniest spot.

The town is home to nearly 52,000 people, and in the past few years its port has seen a large amount of investment and regeneration. 

The Isle of Wight receives the gold medal for sunshine. Located just off the south coast of England, this little island is famous for its sunny weather, seafront promenades and beach huts. It’s no surprise that Queen Victoria regularly chose to retreat here. 

The Met Office has several climate stations on the Isle of Wight, but it’s the one in the small town of Shanklin (population: 9,000) that tops the UK sunshine charts. 

With 1,976 hours of sunshine per year, the Isle of Wight is a whopping 573 hours up on the UK average (1,403).

The Met Office has more than 300 climate stations dotted around the UK which accurately record the weather all year round. These stations monitor a number of things, including minimum and maximum temperature, days of air frost, rainfall, and - most usefully for us - hours of sunshine. The vast majority of climate stations (bar a few exceptions) tell you the average number of annual sunshine hours recorded there between 1991 and 2020. 

Click here for a map of all the Met Office weather stations, and click here for an explanation of how the Met Office measures sunshine and radiation. 

Do solar panels still work in less sunny areas?

There’s no doubt that access to direct sunlight works as a boost for solar panels – that’s why most people put them on south-facing roofs if they can.

But it doesn’t mean you need balmy weather for your solar panels to work effectively. 

Based on a household experiencing average UK irradiance with a 4.4kWp solar panel system and a 5.2kWh battery, it’s possible for solar to cut your electricity bills by up to 103%. The household in this example is using 3,500kWh of electricity each year and is signed up to the Intelligent Octopus Flux export tariff. 

In summary, hours of sunshine certainly help, but other factors like roof angle, orientation, shading, and panel quality also matter. If you're interested in switching to solar and want to find out how much you could save, click the button below and provide us with a few details. 

Find out which places in the UK get the most sunshine (based on 1991-2020 Met Office data) and where solar panels would work best.

The 11 sunniest places in the UK [2024]

The 11 sunniest places in the UK

☀️ Solar is the world’s cheapest source of renewable energy, at $876 per kilowatt

🌊 Hydroelectric power is the most efficient source of renewable energy

💨 Of all renewable sources, wind contributes the most to the UK’s electricity mix

The world is enduring an ongoing climate crisis and renewable energy is one way to slow the whole thing down. However, every source of renewable energy has its own unique advantages and disadvantages - for instance, some are cheap but very dependent on location, whilst some are enormously expensive but a lot more versatile. 

In this article, we’ll run through the five best five types of renewable energy based on efficiency, cost, and accessibility. And we’ll also explore how popular each one is in the UK.

What is the best type of renewable energy?

There’s no ultimate ‘best’ type of renewable energy, because it depends on so many different factors. For instance, the best renewable energy for a hot, dry country that has no coast line would be very different to a wet, windy island nation (e.g. the UK). 

However, if we break it down into categories, there are some clear winners. Hydroelectric power is the most efficient (at 90% or higher), while solar energy is the cheapest (at $876 per kilowatt) and also the most accessible to households. 

Specifically in the UK, wind energy is unsurprisingly the most. Our geography is perfectly suited to it, and in 2022 wind turbines covered almost one quarter of the country’s electricity needs. 

In no particular order, here’s our rundown of the five best sources of renewable energy right now. 

Solar energy works by converting natural light into electricity, making use of strategically placed solar panels to get as much exposure to daylight as possible. When light particles (called photons) hit a solar panel, an electric charge is created, resulting in electricity.

Electricity is then converted from direct current (DC) to alternating current (AC), which allows it to be used at home.

Crucially, solar panels only need daylight to work effectively - not direct sunlight - so they generate electricity even on cloudy days. 

Whilst the manufacture of solar panels has a carbon footprint, the clean electricity produced during each panel’s lifetime obviously makes up for this. Also, at the end of a solar panel’s useful life it can be broken down and recycled - although there is currently only one place in the UK that can do this (in Scunthorpe). 

Solar power is the cheapest renewable energy on this list, costing just $876 per kilowatt produced worldwide in 2022. In terms of domestic applications, a 3kWp solar panel system (roughly the right size for a three-bedroom property) will cost around £9,000 - including installation.

Solar panels are getting more efficient all the time, with recent efficiency records hitting over 40%. However, most household solar panels range between 15% and 23%. This is pretty low compared to other sources of renewable energy, but nothing beats solar when it comes to accessibility on a domestic scale.

In the UK there are over 1.2 million households with solar panels, which equates to roughly 4% of the country’s housing stock. The energy crisis naturally triggered a huge spike in demand for solar, and the Guardian reports that there were more than 17,000 domestic solar installations in each month of 2023. 

However, in 2022 just 4.4% of the national grid’s electricity came from solar, which is very small compared to other renewable sources - such as wind (at 23.3%). 

To learn more, check out our rundown of the top 13 countries for solar energy consumption. 

The best location for wind turbines is ultimately where the wind blows the most, which is typically offshore. The process is very simple: the wind’s kinetic energy moves the turbines’ blades, which drives a generator.

Some people have voiced concerns about the noise created by a wind turbine, but the level of disturbance is exaggerated. Today, a wind farm operating 750 feet away is the same volume as a kitchen fridge, and this noise is usually masked by the sound of the wind itself. There are also concerns that wind turbines kill birds, however not nearly as many as those killed by fossil fuel projects - as the MIT Climate Portal reports. 

The manufacture of the turbines themselves obviously has a carbon footprint, but once a wind turbine is in place the electricity it generates is entirely green. 

In most cases, wind energy is generated on an industrial scale, but it is still possible to use at home with small, roof-mounted wind turbines. The main issue is that planning regulations are strict, and also you need to live in a particularly windy area for it to be worthwhile. 

In 2022, the global cost of wind energy was $1,274 per kilowatt, which makes it the second cheapest on the list. Turbine costs range widely depending on the application; a small domestic turbine will cost just a few hundred pounds, whereas an industrial turbine can cost millions.

Wind turbines need a wind speed of nine mph or more to be effective. The United States Environmental Protection Agency estimates that wind turbines work at an efficiency of 20-40%.

In 2022, wind made up 26.8% of the UK’s energy generation, making it the UK’s primary source of renewable energy. There are now nearly 11,500 wind turbines in the UK, the majority of these being onshore (although it’s the offshore wind farms that generate more electricity, due to bigger turbines and more wind). 

Hydroelectric energy is the generation of electricity from moving water. This might include the power of the tides, or the momentum generated by waterfalls. It also covers man-made bodies of water, including reservoirs and dams. 

The creation of some of the man-made water features – and the infrastructure required to maintain them – has a carbon footprint, and it can also lead to widespread disruption of human habitats and wildlife. 

You can set up a hydroelectric system at home, but it requires access to a body of water that you have permission to use – which, for most people, is a high bar. 

Hydroelectric power is much more expensive than solar and wind, with its global cost per kilowatt in 2022 coming in at $2,881. On a domestic scale, the Centre for Alternative Technology estimates a 1 kilowatt (kW) battery-charging system would cost between £5,000 and £6,000, excluding installation.

Modern hydroelectric energy is extremely efficient, with an efficiency rating of 90% or higher. Compared to solar (approx. 20%) and wind (approx 30%), hydroelectric is phenomenally efficient.   

How popular is hydroelectric energy in the UK?

Just 1.8% of the UK’s electricity generation comes from hydroelectric power, making it smaller than wind and solar. However, the use of hydroelectric has grown significantly in the past couple of decades, with the number of hydro facilities increasing by more than five-fold between 2003 and 2022. 

Geothermal energy is electricity generated from the natural heat beneath the surface of the earth. There is a lot of thermal energy stored in the rocks and fluids in the centre of our planet, which is constantly escaping out to the surface. Hot water is drawn from deep underground using high pressure, and then once the pressure drops it turns into steam. The steam then turns a turbine which generates electricity. 

The construction of piping systems and digging of boreholes is an intensive industrial process that leaves a carbon footprint, but the clean electricity generated makes up for this. 

However, geothermal plants can sometimes create small earthquakes, as well as small quantities of air and water pollutants. These plants also require large amounts of water for cooling. 

It is possible to have a domestic geothermal system (known as a ground source heat pump), but this is a bit different to the large-scale industrial process. On a residential scale there’s no steam, no turbine, and no electricity generation - instead, the pump extracts warmth from the earth and uses this to heat water on the surface. 

Geothermal energy is the most expensive renewable energy source in this list, costing a whopping $3,478 per kilowatt in 2022. Domestic geothermal costs are similarly pricey, with the Energy Saving Trust estimating that a ground source heat pump will set you back somewhere between £28,000 and £49,000. 

A global review of geothermal plants revealed that the average efficiency is 12%, although it has the potential to reach around 21%. In contrast, a domestic ground source heat pump can reach efficiencies of 300-400%, although this efficiency refers to heat generation as opposed to electricity generation.

How popular is geothermal energy in the UK? 

The role of geothermal energy in the UK’s green transition is extremely small. In terms of electricity generation geothermal energy contributes precisely 0%, and in terms of heat demand it covers just 0.3% of the UK’s annual demand. 

Natural occurrences of geothermal activity (e.g. hot springs) have always been a huge attraction, but geothermal as a broader energy source is limited: the US is the world’s largest user, but even there it makes up only 0.4% of total electricity generation. 

Ever since humans discovered fire, biomass has been a source of energy. On a small scale, biomass is usually the burning of plants or wood, but at an industrial level it can involve the incineration of domestic or agricultural waste, or crops that have been specifically grown for the purpose of burning.

However, whilst biomass energy is renewable, it is arguably not sustainable. This is because there is carbon dioxide released whenever organic matter is burnt, making it the only source of energy in this list that doesn’t create clean electricity.  

There is also the issue of the infrastructure required to use it at scale, and the fact that intensive biomass, even on a domestic scale, can quickly lead to deforestation. 

On a cost level, biomass is also not particularly cheap. In 2022, the global average installation cost per kilowatt was $2,162, which is only a few hundred dollars less than hydroelectric. 

While modern biomass plants have been engineered to achieve efficiencies of up to 40%, the domestic efficiency of biomass tends to be 2-3% because so much heat is lost as the fuel burns. 

In 2022, biomass energy contributed 5.2% to the UK’s national electricity mix, which is better than solar, hydroelectric, and geothermal - but not as strong as wind. 

The UK produces about 65% of the fuel it burns for biomass energy, and it imports the remainder from other countries. 

What’s the cheapest type of renewable energy?

Of the five key sources of renewable energy, solar is the cheapest. Check out the table below for a rundown of the costs.

<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;">Type of renewable energy</th>
    <th style="padding: 12px;">Average cost per kilowatt in 2022</th>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Solar</td>
    <td style="padding: 12px;"><center>$876</center></td>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Wind</td>
    <td style="padding: 12px;"><center>$1,274</center></td>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Biomass</td>
    <td style="padding: 12px;"><center>$2,162</center></td>
  </tr>
  <tr style="border-bottom: 1px rgba(0,0,0,0.1) solid;">
    <td style="padding: 12px;">Hydroelectric</td>
    <td style="padding: 12px;"><center>$2,881</center></td>
  </tr>
  <tr>
    <td style="padding: 12px;">Geothermal</td>
    <td style="padding: 12px;"><center>$3,478</center></td>
  </tr>
</table>
</div>
</div>

This depends on whether the focus is on cost, efficiency or domestic accessibility. 

Solar is the cheapest and the most accessible to households, but hydroelectric power is the most efficient (at 90% or higher). 

According to the United Nations, hydroelectricity is the most widely used renewable energy worldwide - accounting for 60% of global renewable electricity generation. 

What is the best type of renewable energy in the UK?

Wind, both onshore and offshore, contributes more to the UK’s electricity production than any other source of renewable energy. 

This is because the UK’s island geography creates ideal locations for wind turbines. 

Which renewable energy source is the most sustainable?

Wind, solar, geothermal and hydroelectric are all equally sustainable, given that they all draw on sources that are not likely to expire any time soon. 

In contrast, biomass energy creates a lot of carbon dioxide in the process of generating electricity, which makes it far less sustainable. 

Is nuclear power a renewable energy source? 

While nuclear power is considered key to the National Grid’s ambition of achieving Net Zero by 2050, it cannot be classed as a renewable energy. 

This is because nuclear energy requires uranium – and, like fossil fuels, there is a finite amount. According to the Nuclear Innovation Alliance, there is enough uranium to supply 100 years of current demand. 

Find out the ultimate top five sources of renewable energy based on cost, efficiency, accessibility and more.

Joanna Hunter

Posts from Joanna Hunter

How do solar panels work?

The 11 sunniest places in the UK

The five best types of renewable energy