How do solar panels work?

Solar panels are becoming a popular form of green energy, but how do they convert sunlight to electricity? (Image credit: Adobe)

Learning how solar panels work is the first step when making a decision to invest in a system. With so many factors affecting their efficiency, from your location to the size, shape and angle of your roof, knowing how solar panels produce electricity will help you understand if your home has the ideal conditions. 

In our guide we’ll start by explaining the materials within solar panels and the photovoltaic effect by which they generate an electric current. We’ll then explain how your system converts that current into usable electricity that can power your home, all without producing any harmful emissions. By the end, you’ll have a full understanding of why solar panels are one of the cheapest and greenest forms of renewable energy.

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Solar power is the process of harnessing energy from the sun’s UV rays and converting it into usable electricity. To this end, solar panels use what’s called the photovoltaic process (more on this later). It’s one of the cheapest forms of renewable energy to produce, and accounted for 4% of global electricity consumption in 2021. By 2050, solar power is set to comprise 20% of all electricity.

There are two methods of converting the sun’s rays into electricity. The first – and by far the most popular – is the photovoltaic method. This is what’s used in the solar panels that you see on people’s rooftops and in solar farms. Photovoltaic solar panels convert sunlight directly into electricity and are cheap to produce.

The second method is by using what is called concentrated solar power. Utilising an array of lenses or mirrors, these systems can concentrate light in one area. As this light becomes heat, it creates thermal energy. This can then be harnessed to power an engine to generate electricity.

As you can image, concentrated solar power is more complex and costly to produce. It’s largely only used in industrial applications. Photovoltaic solar power requires fewer elements and less production time. Solar panels can be mass-produced. With prices for solar panels falling over the last two decades, plus many solar panel grants incentivising homeowners to make the switch, photovoltaic solar power is by far the most popular form of solar energy.

Understanding how solar panels work can help you make an informed decision about whether they are the right solution for your home. (Image credit: Adobe)

Here is a general breakdown of how solar panels work:

1. Sunlight hits the solar cells
2. Increased temperature causes electrons to move, creating a current
3. Plates and wires in the panel turn the current into usable electricity

To understand how solar panels work, you need to start with the photovoltaic process. The cells within a solar panel are comprised of semiconductive material, which is typically silicon. When light from the sun lands on these cells, photons within the electromagnetic radiation from the sun generate heat. This heat causes electrons within the semiconductive cells to start moving. The moving electrons create an electric current. This is called the photovoltaic effect. 

Solar panel manufacturers have also improved their designs over the years to help increase the amount of sunlight they can absorb. This is achieved with anti-reflective coatings and a glass casing to both protect the cells from the elements and regulate the temperature inside your solar panels. Contrary to popular belief, if a solar panel gets too hot, the photovoltaic effect weakens and the panel’s efficiency will drop.

But the photovoltaic effect, on its own, does not create electricity you can use. Also within the solar panel are plates and wires that will turn this electric current into direct current (DC) electricity. Your solar panels then feed this DC electricity to your inverter, which converts it into alternating current (AC) electricity. AC electricity is usable energy that can power your home appliances and electronics.

Determining the exact cost of solar panels can be tricky and varies depending on a number of factors, including the size of your roof and your typical electricity usage. Individual solar panels can cost anywhere from £100 to £350 each, but there are other costs involved such as installation, solar inverters and optional batteries and optimisers. Typically, you can expect to pay anywhere from £5,000 to £10,000 or more for an entire solar power system including installation, though the cost might be higher if you choose a premium solar panel brand.

A solar inverter takes the DC energy produced by your solar panels and feeds it through a transformer. This transformer will reduce the voltage of the current and convert it to AC at the same time. Not only can you use this AC electricity throughout your home, you can also sell it back to the National Grid or store it for later use if you have a battery connected to your system.

There are three types of solar inverters to choose from: string inverters, micro inverters or power optimisers.

String inverters are what you see on most solar panel systems that were installed in the 2000s and 2010s. In this system, one’s solar panels are set up in rows and connected to a single inverter. However, because they are all connected, any shade affecting the performance of one panel will bring down the efficiency of the whole system. This downside led to the development of what more people are using today: micro inverters.

Micro inverters are fairly new technology. These are fitted to each individual solar panel so that if one panel is in the shade, only that panel sees a drop in output. Micro inverters are more expensive than string models, but they vastly improve the efficiency of your system as a whole. Over time, the increased energy production they provide should make up for the extra cost involved.

Power optimisers are another new technology designed to improve the efficiency of your solar panels. Like micro inverters, these are mounted to each individual solar panel. The difference is, power optimisers don’t cover the energy from each panel. Instead, they feed the DC electricity to a string inverter. Power optimisers are sort of a middle range option between string and micro inverters. They are less expensive than micro inverters, but not as efficient. However, they are more efficient than a string inverter on its own.

Solar inverters turn the DC power produced by solar panels into usable AC electricity that can power an entire house. (Image credit: Adobe)

A solar inverter typically costs around £500 to £1,500. The exact amount depends on which of the three types you buy. What’s more, the type of inverter you need will depend on your property type, its location and how big your system is. 

When you get a quote for your solar panel system, make sure that the cost of the inverter is included. You should also ask your installer to give you a recommendation for the best option for your system. A good installer will ask you about the amount of electricity you consume, survey your roof and then make a recommendation for the optimum system requirements. 

Most new solar inverters come with a 10-year warranty, and you should expect it to last around 12 years before you want to replace it. Like your solar panels, your inverter’s efficiency will start to decrease a little each year.

Whichever brand of solar panels you go with, the manufacturer will have a stated efficiency rating on their website. However, the true efficiency of solar panels depends on a variety of factors. First, of course, is the quality of your panels. There is a reason why some solar panels are more expensive than others. High-quality solar panels are thicker and the photovoltaic cells are purer, meaning they can output more energy in an efficient manner. 

Most of the higher quality solar panels are also smaller and need less space to generate the same amount of energy as the cheaper options. You can typically fit more of these high-quality solar panels on your roof, increasing your system’s output.

Your roof also plays an important role in the efficiency of your solar panels. The best spot for solar panels is on a south-facing roof with no surrounding trees to shade it. 

The angle of the roof is also important and can affect how much sunlight your solar panels will absorb. The ideal roof angle is between 25 and 75 degrees to get the best performance from your solar panels. Of course, where you live in the UK also changes the angle of the sun. Again, these are all considerations to discuss with your installer when seeking a quote.

Even on cloudy days, solar panels will continue to produce electricity from the light that hits them. (Image source: Adobe)

How solar panels work in adverse weather is perhaps the most common question about solar energy, and the simple answer is: if you can see outside with your eyes, then your solar panels are working. How much light there is, of course, affects how much electricity they are able to produce. And poor weather will reduce their efficiency. But solar panels work in all weather.

Summer is when solar panels perform best. The days are longer and the light from the sun is at its strongest. Because of this, many people believe that solar panels thrive in the heat, but this isn’t actually the case. As we explained earlier, if solar panels get too hot, the photovoltaic effect is less pronounced. Solar panels will generate less voltage and become less efficient in the heat. 

The ideal conditions for solar panels are cooler weather with full sun. This might lead one to think they should perform well in winter; however, the shorter days and extra cloud cover mean their output isn’t as strong. What they do produce, though, they do very efficiently.

The UK is often cloudy and rainy, leading some to think it’s not an ideal climate for solar panels, but because it has mild temperatures year-round and receives more than eight hours of daylight, the UK is an ideal climate for solar energy.

Because the UK is so far north, our days are longer from spring through summer than other parts of Europe. Solar panels in the UK get access to more light for longer than systems in Southern Europe. This tends to balance out the shorter days of winter.

Solar panels have a lifespan of up to 40 years. Most manufacturers state their solar panels will generate 85-90% of their output potential after 25 years. Some even provide warranties guaranteeing this. For instance, SunPower offers a 40-year warranty on its Maxeon 3 solar panels.

If properly installed and cared for, your solar panels should easily last you 30 years and likely up to 40 before you’ll want to consider replacing them for a newer system with more output potential.

While there are gas emissions from manufacturing solar panels, they can help households cut their carbon footprint by creating renewable energy. (Image credit: Adobe)

While there is some pollution that will inevitably be created by their manufacturing process, solar panels remain the single best way for people to directly reduce their carbon footprint. 

Solar panels are the purest renewable energy that exists. Sunlight will never run out (for the next billion years, at least), and there is plenty of it to go around. Solar power is also ideal from an environmental perspective because it produces no emissions. The photovoltaic process of creating energy all happens within the space of your home. No greenhouse gases need to be produced to deliver this energy to your appliances and electronics.

Traditionally, we’ve had to burn fossil fuels to create electricity and deliver it to our homes, so when you compare the two methods, photovoltaic energy is infinitely cleaner and more sustainable. When looking at the reduction in emissions, it’s been said that just one home making the switch to using solar power has the same impact as if that homeowner planted several hundred trees every year of the life of their solar panel system.

And while there is a manufacturing process that does create emissions, solar panels last an incredibly long time with little maintenance required. The same cannot be said for traditional methods of creating electricity.

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