We explain the method of converting sunlight into electricity in this detailed guide.
A full guide explaining the workings of solar panels.
As global interest in sustainable energy sources grows, understanding the mechanics and benefits of solar technology becomes increasingly vital.
Solar panels are at the forefront of this green revolution, offering a clean, renewable way to power our homes and industries.
Check out our comprehensive guide that uncovers how solar panels harness the power of the sun, exploring their inner workings, the science behind their efficiency, and their role in promoting environmental sustainability.
A solar panel is a device designed to capture energy from sunlight and convert it into electrical power.
Solar panels consist of multiple photovoltaic (PV) cells that are interconnected and enclosed in a frame. These cells are made from semiconductor materials, typically silicon, which generate electricity when exposed to light through the photovoltaic effect.
The photovoltaic effect is the process of generating voltage or an electric current by converting light, i.e., photon particles from the sun, that hit a PV cell.
The electricity produced by solar panels is typically direct current (DC) and can be used directly, stored, or converted to alternating current (AC) for use in homes, businesses, or fed back into the electrical grid.
Solar panels are key components in solar energy systems, providing a renewable and sustainable source of energy.
Four main types of solar panels are employed and on the market today, with each having its own distinctive characteristics. They are:
Monocrystalline solar panels are made from a single, continuous crystal structure of silicon, which gives them a distinctive dark black color and a high level of efficiency.
These panels are constructed from silicon ingots, which are cylindrical in shape. These ingots are then cut into wafers in a specific orientation to optimize performance, although this comes with a lot of waste - sometimes over 50% - and thus gives it a higher price tag.
The high purity of the silicon used in monocrystalline panels enables them to achieve higher efficiency rates, typically between 15% to 20%, because electrons that generate a flow of electricity have more room to move.
When exposed to sunlight, the electrons in the monocrystalline silicon are excited and begin to flow, creating an electrical current that is captured and converted for practical use.
The single-crystal structure also enhances their durability and longevity, making them a popular choice despite their higher cost compared to other types of solar panels.
Polycrystalline solar panels, also known as multi-crystalline solar panels, are made from multiple different silicon crystals that are melted together into a mold before being cut into wafers. This process gives them a distinct, speckled blue appearance and makes them less expensive to produce compared to monocrystalline panels.
When sunlight strikes the surfaces of polycrystalline solar panels, it activates electrons across the silicon crystals, generating electricity through the photovoltaic effect.
The efficiency of polycrystalline solar panels typically ranges from 13% to 16%, slightly lower than their monocrystalline counterparts due to the presence of multiple crystals which can create boundaries that impede electron flow. Despite this, they offer a good balance of cost and efficiency.
These panels are a popular choice for residential and commercial applications where space and budget constraints are considered.
Passivated Emitter and Rear Cell solar panels, or PERC for short, represent an advancement in solar technology that improves efficiency and performance. They are an upgraded version of standard monocrystalline solar panels.
PERC panels feature an additional passivation layer on the rear side of the photovoltaic cell, which reduces electron recombination and improves light capture. This layer reflects unabsorbed sunlight back into the cell, giving the electrons a second chance to generate electricity.
As a result, PERC panels achieve higher efficiency rates, especially in low-light conditions, because they harness more solar energy with the same surface area as traditional panels.
Their improved efficiency, which is typically 5% more efficient than the similar monocrystalline panel thanks to the passivation layer, makes them ideal for installations where space is limited but high power output is needed.
Thin-film solar panels are a lightweight, flexible alternative to traditional solar panels, consisting of layers of photovoltaic material applied directly onto surfaces like glass, plastic, or metal. They are made from different materials, each providing a differing range of efficiency.
The different materials used to create thin-film solar panels are:
Each of these materials produces layers within the solar panel that are much thinner than traditional silicon wafers and thus make the panels adaptable to varied applications.
Although they generally have lower efficiency rates compared to crystalline silicon panels, thin-film panels excel in diffuse light and high temperatures, maintaining steady performance.
They work by allowing sunlight to activate electrons within the thin semiconductor layers, creating an electrical current through the photovoltaic effect.
Their flexibility and ease of installation make them ideal for integration into unconventional surfaces, such as building facades and portable devices.
To begin understanding how solar panels work, we first must look at the science of photovoltaic cells. We’ve already given a quick explanation of what the photovoltaic effect is, but now let’s break it down further.
Solar panels are made up of many small photovoltaic (PV) cells. These cells are primarily made from silicon, a semiconductor material, but as we know from the above, the different solar panels can be made from different materials. Regardless, the process with photovoltaic cells is still the same, and for this example, we shall stick with cells made from silicon.
When sunlight strikes a solar panel, the photons (light particles) from the sun carry energy that excites the electrons in the silicon cells.
When these photons hit the silicon cells, they knock electrons loose from their atoms, creating free electrons. These electrons naturally flow towards a positively charged layer, creating an electric current.
This movement of electrons generates a direct current (DC) of electricity. However, most homes and electrical devices operate on alternating current (AC), not DC.
This is obviously a very important and valid question because if the process generates a direct current of electricity, then how are homes powered by solar panels when they require alternating current?
That’s where the role of an inverter comes in, one of the most important components in a solar panel.
Once the DC electricity has been generated, it then flows into the inverter device. The inverter's job is to convert this DC power into alternating current (AC), which can be used in your home, business, or connected to the power grid.
It achieves this by essentially switching the direction of a DC input back and forth very rapidly, which creates pulses of current that alternate between positive and negative. The pulses are then filtered and smoothed by capacitors and inductors to form AC electricity.
Once the electricity is in AC form, it can power all your appliances and devices. Any surplus electricity generated can be stored in a battery system (if available) or fed back into the local power grid depending on what the solar panel is used to power.
Some factors can affect the efficiency of solar panels, including weather conditions, solar panel placement, and even ever-bettering technology.
The amount of solar energy striking a panel directly affects its output. Solar panels are most efficient when receiving direct sunlight.
This of course can impact users in the UK as the British sun is as rare as a four-leaf clover.
Cloud cover, fog, and rain can significantly reduce the amount of sunlight reaching panels, lowering their output.
However, panels can still produce some electricity even under diffuse light conditions. Even on less ideal days, solar panels are still capable of producing energy, although it may be 10 to 25% of the energy output from a sunny day.
Solar panels are most efficient when positioned to face the sun directly, so it is important to plan exactly the best place for the panels to ensure they get as much sunlight as possible.
Any shading from nearby trees, buildings, or other structures can also block sunlight, thus reducing efficiency. As such, the panels should be installed in an unobstructed area to ensure that they receive consistent sunlight.
Finally, the direction the panels face also matters. South-facing panels are generally ideal, but east or west-facing panels may be effective depending on local solar patterns.
You want the panels ideally facing south because they will generate the most power. If facing east or west, they could generate 15% less power, and 30% less if facing north.
As described earlier, the different types of solar panels have varying efficiency levels due to the materials used and production methods.
Newer technologies, like Passivated Emitter and Rear Cell (PERC) and bifacial panels, capture more energy by reducing electron loss or harnessing sunlight from both sides of the panel.
This helps to negate the need for idyllic panel placement and angle, although by still keeping to both of those, you can ensure maximum efficiency.
Special coatings on the glass surface of panels can reduce light reflection and increase the amount of sunlight absorbed.
Coating is basically a passive cooling technology, keeping the PV cells and the panels relatively cool on the hottest sunny days.
Not only will coating boost energy efficiency, but it will also prolong the life of the PV cells. The cells can reach temperatures upwards of 55 degrees Celsius, and with a coating such as a thin layer of silica glass, the cells will keep themselves cool by turning away all unwanted thermal radiation from the sun.
As mentioned before, where you install your solar panels is important. The whole process is done to ensure maximum efficiency once they are up and running, and thankfully for you, it is not on you to figure this out, though it could be if you’d like it to be.
Installation can be and really should be carried out by a professional - and that’s not just your local electrician, either. Professional solar panel installers require certifications and accreditations, specifically MCS accreditation.
That’s not to say you can’t install your own panels. You certainly can, but it's not wise to do so for multiple reasons.
There are certain rules as to where to install the panels on your roof. You generally won’t need planning permission to do so unless you live in a historical or listed building.
As for where they can be installed, they should be positioned below the property’s highest point (excluding chimneys) and should not extend more than 200mm from the roof surface. This is in due part to ensure that the installation of the panels minimizes its impact on both the property’s external appearance and the surrounding environment.
If the roof or the building itself is structurally weak, planning permission would be wise to consult so they can evaluate the condition and determine if installation would be possible.
All this can be avoided though by using a professional installer, who as part of their accreditation will know all this and will know how to best approach installation.
It is also important to note that should you ever intend on selling the building after installing the panels yourself, you may find it harder to convince buyers of the safety compared to if a professional had done it.
There are a number of steps taken to ensure proper installation. This is not a handy checklist that you can run through while installing your panels yourself, but instead, the steps taken by professionals during installation.
Regular maintenance is key to keeping your panels running as efficiently as possible while preserving their lifespan.
We spoke of coating that will help in both of those; however, there are more things you can do manually that will help keep the panels in good condition and working as they should.
Regular cleaning may be needed as things like leaves, dust, overgrowth, and bird droppings can accumulate on the panels, reducing efficiency.
Cracks, loose wires, and rust may also naturally happen over time, as may loose or faulty wiring. This can also be the same for the components like the inverter.
In these cases, it is best to get a professional back in to inspect the general condition of everything. If there is anything wrong, they will be able to sort it out safely and restore the panels back to the highest efficiency it is capable of at that time.
There are pros and cons to solar panels as there are with anything. Of course, the biggest positives are the environmental factors, given that solar power is a renewable energy source.
Unlike fossil fuels, solar energy is clean, sustainable, and won’t run out. It also decreases gas emissions and air pollutants, helping the general climate and improving air quality.
Solar panels can also be great cost savers, with excess power generated being sold back to the grid through net metering.
On the subject of monetary benefits, the UK government will also give grants to those who have solar panels installed in their homes as a way to incentivize more people to get them installed.
If you power your house or building solely through your own solar panels, then you will of course benefit from your own power. There would be no bottleneck at peak times because of more users and you would be less vulnerable to price fluctuations that we see time and time again in the energy sector these days.
One last benefit is the continued improvements in solar technology, bringing increased efficiency and affordability and thus making solar more accessible.
But there are downsides, some of which we have already touched on.
Initial upfront costs may be rather high due to factors such as safe installation, which is key to solar panel efficiency, which also leads onto another point of having them work as they should do.
Keeping them as efficient as possible does come with a lot of manual checking to ensure they are clean and undamaged, something which isn’t exactly easy when the panels are on your roof.
The weather is also something of an issue as if there is a prolonged spell of poor weather, the efficiency simply won’t be there and you won’t be generating as much power (as explained before).
While you won’t simply run out of electricity in these cases, you may not see the benefits as well as you will have done when there is good weather.
Solar panels offer a promising path toward a sustainable energy future, and hopefully through what we have explored in this guide, with understanding how solar panels work, the types available, and the factors influencing their efficiency, you are now more informed and wiser to the decision about adopting solar energy.
Despite challenges like high initial costs and weather dependency, their long-term benefits - including reduced energy bills, decreased carbon footprint, and increased energy independence - make solar panels an excellent investment.
As technology continues to improve, solar energy will become even more accessible and efficient, empowering us to embrace renewable energy and contribute to a greener planet.
The cost of solar panels can vary significantly based on several factors, including system size, panel type, and incentives.
As we mentioned, the initial costs may be rather high, but government grants can help recoup that and would continue to provide a benefit.
Yes, solar panels can work on cloudy days, but their efficiency and energy output are reduced compared to clear, sunny days.
This won’t mean that you’ll lose all electricity to your home or building, but that the output will simply be lower.
Solar panels are designed for long-term use and typically have a lifespan of 25 to 30 years or more.
Solar panels experience a gradual decrease in efficiency, known as degradation, at an average rate of about 0.5% to 1% per year. Thus, after 25 years, a panel will likely produce about 75% to 87.5% of its original output.
Most solar panel manufacturers offer warranties guaranteeing 80% to 90% of their original output after 25 years. This means that panels should still produce a significant amount of electricity decades after installation.
Proper maintenance, such as regular cleaning and professional inspections, can help maximize panel lifespan and maintain optimal efficiency. But while panels may last several decades, inverters generally need replacement every 10 to 15 years, so it is important to check those every few years to ensure they are working and replace them when needed.
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