6 min read

How do solar panels work?

Last updated on 01 February 2024

Most people are familiar with the fact that solar panels generate electricity, but far fewer people know quite how they do it.

Photo of author Joanna Hunter

Written byJoanna Hunter

The sun rising behind an array of polycrystalline solar panels

☀️ Solar panels convert sunlight into electricity to power your home

🌧️ They work in almost all weather

📈 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.

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How does a solar panel work?

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

The sun shines 

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.

Daylight hits the solar panel 

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.

It creates an electric charge 

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. 

Do solar panels work in all weather?

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.

How efficient is a solar panel?

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.

An array of black solar panels across two sides of a rooftop, with the sun rising above them

Are solar panels getting more efficient?

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.

Do solar panels work in space?

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.

Where do solar panels work best?

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: 

Perovskite solar panels

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 dot 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.

Organic photovoltaics

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.

Zombie solar cells

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? 

1. During daylight, the sun transmits solar radiation to Earth

2. This radiation contain particles of light, called photons

3. Solar panels contain solar cells. When the photons hit the solar cells contained in solar panels, they create a reaction 

4. This reaction results in an electrical charge

5. A solar inverter converts this current from direct current (DC) to alternating current (AC), which can then be used in your home.

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

This depends on the size of the house, the size of the roof, how much sunlight it gets, the type and wattage of panels, and how much electricity you need. 

A useful approach is to work out the average amount of energy you use each month, and the hours of sunlight you can expect. 

You can then multiply these together, and divide by the wattage of the panel you’re using. This should give you the number of panels you need. 

Broadly speaking, a three-bedroom property will need a 3-4kWp solar panel system, which usually means around 8-10 400W panels.

How do solar panels work with your electric bill?

Some people opt to go off grid entirely, meaning they disconnect from the national power system and generate all the energy they require themselves. 

Most, however, stay connected to the National Grid. Once you have solar panels you will notice your electricity bill go down, but you will still need to cover approximately 50% of your annual electricity needs by purchasing electricity from the grid. However, add a battery to your solar panel system and you could use around 80% of the electricity your solar panels produce. 

You can also make money by selling excess electricity to the National Grid.

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