How do solar panels work?

How do solar panels work? And what are the benefits? We explain the technology clearly and simply, and answer some common questions.

By Architectural Digest Editorial Team

October 19, 2023
How do solar panels work? A computer-generated image of solar panels installed on the roof of a modern house.

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We all know solar panels provide various benefits, but how exactly do they work? This article looks at the technology behind solar panels and highlights the benefits they bring to homeowners. We’ll also address some of your most frequently asked questions.

Solar panels are renewable energy devices that convert sunlight into electricity. They help generate electricity, reduce your carbon impact, and save money on energy bills. It’s no secret that energy bills are on the rise, with the average household set to pay £2,500 per year from October 1, 2022, until April 2024. In light of this, many people are thinking about solar panels for their homes in the UK. 

You might feel that installing a solar system is complex and costly, but it doesn’t have to be. Solar panel prices have reduced by 82% over the last decade and the UK government also offers incentives to homeowners. The Smart Export Guarantee (SEG) programme compensates you for exporting electricity to the National Grid, whilst the Energy Company Obligation Scheme (ECO4) provides low-income households with grants to invest in energy-saving devices. Using these grants can help you reduce your emissions, decrease your reliance on the grid, and provide you with savings in the long term.

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How do solar panels work, and how are they made?

The photovoltaic effect is a major part of how solar panels work
Most residential solar panels foster the photovoltaic effect to turn sunlight into usable electricity. (Image credit: Adobe)

Solar panels are made up of semiconducting cells (typically silicon), sandwiched between a backsheet and a glass sheet that protects the panels and allows sunlight to pass through to the cells. The cells are connected by wires soldered onto the cells, which transmit the electricity generated. A metal frame, typically made from aluminium, is used to hold the panel together.

When sunlight hits the solar panels on your home, particles called photons in the sunlight react with the solar panel cells, causing electrons to flow in a process known as the photovoltaic (PV) effect, which generates direct current (DC). An inverter transforms this DC electricity into usable alternating current (AC) electricity. You can use this power for your home, transfer it to the national electrical grid through the utility metre, or even store it in batteries. 

If you wish to store your excess generated electricity for later use, you’ll need to install a charge controller and a battery bank. A charge controller is a device that controls the amount of current flowing to the battery bank. It ensures the battery is working at optimal efficiency. If you intend to rely entirely on solar panels to power your home at night, you will need a battery bank.

The types of solar panels available

Four varieties of solar panels exist. These are monocrystalline, polycrystalline (or multicrystalline), thin film, and hybrid. They are all constructed from silicon but are processed differently.

Monocrystalline

Monocrystalline, or mono silicon, panels are constructed from whole bars of silicon sliced into wafers. They offer the highest silicon purity, allowing them to provide a high power output and reach higher efficiency levels (of over 20%) compared to polycrystalline cell panels. However, they are more expensive. These panels have a sleeker, darker appearance.

Polycrystalline

Polycrystalline, or poly silicon, solar panels are created by melting raw silicon fragments into wafers, which is a quicker and less expensive method than that of monocrystalline panels. Each cell appears blue and dotted, and contains many crystals. They are less costly but offer lower efficiency (up to 15%).

Thin film cells

Thin film (or amorphous silicon) cells are the most cost-effective of the four, but have the lowest efficiency. They’re made from multiple sheets of non-crystalline silicon, which allows for increased flexibility and less weight (about 20 times lighter than mono or poly panels). However, they’re not commonly used for housing projects.

Hybrid cells

Hybrid, or HIT, cells are fabricated by combining thin film and crystalline silicon cells. This combination increases the efficiency of the panels but also bumps up the cost.

Solar roof tiles

A new technology to the market is the solar tile, or solar slate. These are fitted in the same manner as regular roof tiles and can be more visually pleasing than conventional rooftop solar panels. However, these systems are not cheap, costing up to twice as much as a solar panel installation with identical power output.

Ground-mounted systems

Instead of installing rooftop solar panels, you can purchase ground-mounted units. Some cutting-edge systems even rotate to face the sun throughout the day, to maximise the amount of energy produced. However, they take up outdoor space and may require foundations, which can be costly.

We recommend checking the cost-per-watt (£/W) power generated when deciding what kind of solar cells to use. You can calculate this by dividing the cost of the solar system by the power output. The lower the cost-per-watt, the greater the benefits you can realise from your solar panels. However, you should also consider other factors such as warranty, reliability, and performance of the panels.

What factors affect the power output from solar panels?

How do solar panels work diagram
There are several components of a solar panel system, with each playing its part in how efficient the system is. (Image credit: Adobe)

A variety of factors influence the efficiency and power output of solar panels. The first and most important consideration is the quality of your panels and their cells. Thicker, purer photovoltaic cells in the best solar panels for homes are more efficient and produce more electricity. However, these are, as you might expect, pricier.

The size of your system also matters. Typically, the more panels you install, the more energy you can produce to meet your home’s electricity needs. The purer, more efficient solar panels on the market require less area to create the same amount of electricity as the less expensive alternatives. So, if you have limited space it’s worth researching to see if investing in a more expensive system could pay off in the long run.

Your roof is another critical aspect of the performance of your solar panels. Is it south-facing with direct sunlight? Do trees surround your roof and cast shade in the summer? These are important things to think about, and your installer can help you with them. Solar panels offer the highest power output on a south-facing roof that receives direct sunshine and is not obstructed by shade.

The angle of the roof is also influential. As the sun’s angle varies depending on where you live, the slope of your roof will influence how much sunlight your panels are exposed to, and can therefore absorb. According to installers, the optimal angle ranges between 25 and 75 degrees.

How long do solar panels last?

Solar panels for homes have an average life span of 30 years. After this point, their efficiency begins to deteriorate, producing less electricity from their cells. After 25–30 years, most solar panels claim to be able to generate 85%–90% of their production capacity.

Many solar panel manufacturers also guarantee that the performance will not fall below 80% over the warranty period, lasting up to 20–25 years.

In the right conditions and with adequate care, your solar panels might last for more than 40 years before needing to be replaced.

How many solar panels will it take to power my house?

There are several things to consider when determining how many solar panels you need for your home. The most critical element here is how much energy you use.

The majority of solar panels generate 250 W of power with four hours of full sunlight. Using this information, you can determine the number of panels needed for your home by dividing your power requirement by 250 W, which equates to four solar panels per kilowatt required. For example, you will require 12 solar panels to provide electricity to a three-resident household with an average energy consumption of 3 kW.

The most common solar PV system size for houses in the UK is 4 kW, which is sufficient for up to four people. By using the given calculation, a 4 kW system would require 16 solar panels on average. If space is an issue, you can always use a solar system to power a portion of your home rather than the entire thing. However, this solution may not be as profitable in the long run.

Different brands offer solar panels with varying efficiency and power output. It is crucial to consider your options carefully, as this will dictate how many panels you will need to install. The higher the efficiency and power output of your solar panels, the fewer you’ll need to achieve the required power output.

Are solar panels worth it?

A mother and father showing their young child solar panels
Solar panels are an investment for the future, offering reduced energy bills and a lower carbon footprint. (Image credit: Adobe)

Many homeowners in the UK are considering installing solar systems due to the rising energy costs—but bearing in mind the initial cost, are solar panels worth it? Here is a list of the advantages you can benefit from by installing solar panels for your home:

Reduced energy bills

As energy costs are rising, solar panels could help alleviate the strain on your household budget. They rely on sunlight, a free and abundant energy source. The money you save will be determined by the size of your solar system and your household’s electricity consumption.

You don’t need to be concerned about generating electricity in the UK’s often overcast weather, either. Solar panels only require light to work, so every day, regardless of the conditions, your system can harness solar energy from anywhere in the UK. However, it’s true that more power output is achievable in brighter conditions.

Get paid for exporting electricity to the National Grid

You may not consume all of the electricity generated by your solar panels, and it’s up to you what to do with the excess energy. You can choose to either store it for later use or export it to the National Grid and receive compensation from energy firms through the SEG scheme.

Minimal maintenance

Solar panels require very minimal maintenance and with companies providing warranty periods of 20–25 years, you can be assured they are reliable. You will typically need to inspect and clean your panels at least twice a year to ensure they perform at optimal levels—or more in areas with high pollution and adverse weather conditions.

Lower your carbon footprint

A significant advantage of installing solar panels is the ability to switch to green, renewable energy. Solar panels, unlike other energy sources that rely on fossil fuels, can help reduce your carbon footprint and environmental impact.

Frequently asked questions about solar panels

Do solar panels work on cloudy days?

Even on cloudy days, solar panels will generate electricity. Their output won’t be as high as on sunny days with little cloud cover, but the rule still applies: If you can see outside, there is enough light for solar panels to do their job.

Do solar panels work when shaded?

When solar panels are shaded, their output decreases. You will obtain the best output from panels facing south with no obstructing shade. One concern with solar panels is that if one panel is shaded, it can reduce the entire system’s output because the panels are interconnected. However, new improvements in inverter technology allow each panel to work independently.

Do solar panels work at night?

Solar panels do not operate at night. However, any electricity that isn’t used during the day is either fed back to the national power grid or stored in batteries, depending on the system you choose.

Will the electricity generated from solar panels power my entire home?

You can certainly generate enough power for your home with solar panels, but this depends on several factors such as the efficiency of the panels, size of your roof, and location, etc. We recommend not relying solely on solar power and instead using a solar system alongside electricity from the National Grid.

What are the drawbacks of solar panels?

The main drawback of solar panels is the high initial cost—approximately £6,500 for a residential system according to the Energy Saving Trust. Another disadvantage is the reliance on weather conditions, with output dropping during periods of bad weather. Finally, solar panels require a lot of space to meet power requirements, another drawback of the technology.

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