Types of solar cells explained

The best solar panels have come a long way in the last decade or so, with innovations to boost their performance and efficiency. So, what types of solar cells power the UK’s solar panels in 2024? Below, we’ll unpack three generations and seven types of solar panels, including monocrystalline, polycrystalline, perovskite, bi-facial, half cell and shingled.

Read on to explore the advantages and disadvantages of each and learn which type of solar cell and panel is best for your UK home.

There are seven different types of solar panels available in the UK in 2024:

• First generation – crystalline
  • Monocrystalline
  • Polycrystalline
• Second generation – thin film
  • Silicon – a-Si
• Third generation
  • Dye-sensitised solar cells (DSSCs)
  • Organic
  • Perovskite
  • Concentrated photovoltaic (PV) cell – concentrated PV (CVP) and highly concentrated PV (HCPV)
• Cutting edge and future technology
  • Heterojunction technology (HJT)
  • Bifacial cells
  • Half-cut cell or cut cell
  • Shingled solar cells

We’ll unpack each solar cell and panel type in greater detail below.

First-generation solar panels are the most used PV technology and have been around since solar energy’s earliest days.

First-generation solar panels utilise traditional crystalline silicon technology. This comes in two types – monocrystalline and polycrystalline – based on the manufacturing process.

Monocrystalline

Monocrystalline solar panels are made with silicon of the purest quality, composed of a single crystal structure and cut carefully. These panels have a black colour and are highly distinctive. They offer one of the highest energy efficiency rates (around 15 to 20%) among solar panels – meaning they don’t require as much space as more inefficient panels – and perform well in low-light conditions.

Monocrystalline panels are also less affected by higher temperatures than their polycrystalline counterparts, giving them a longer lifespan, so they tend to come with a 25-year manufacturer warranty – the longest on the market. This also makes monocrystalline solar panels ideal for homes in hotter, brighter areas.

The only drawbacks? All that longevity and quality come at a price, and monocrystalline solar panels are among the most expensive on the market.

Polycrystalline

Polycrystalline solar panels are made slightly differently from their monocrystalline cousins. Instead of cutting the panels, manufacturers melt the silicon and pour it into moulds – an easier and cheaper manufacturing process.

This, in turn, makes polycrystalline solar panels more affordable than monocrystalline; while they don’t quite match the latter’s energy efficiency, the two types of solar panels are on par when it comes to durability and longevity.

Polycrystalline solar panels’ energy-efficiency rate, around 13 to 16%, equates to a lower output; this makes them less space efficient and means you’ll require more room on your roof than you would with the higher-performing monocrystalline panels. Polycrystalline panels also can’t boast the same levels of high-temperature performance as monocrystalline types, which makes them less suitable for the hottest environments.

Second-generation solar panels emerged after the crystalline silicon type. Characterised by their use of alternative manufacturing processes and semiconductor materials, the second generation includes thin film, dye-sensitised and organic solar panels.

Most solar panels from the second generation rely on thin-film solar cell technology. Thin-film solar cells are made with multiple layers of PV material on top of a substrate, such as cadmium, copper or silicon.

Silicon thin-film solar cells (a-Si)

Silicon thin-film solar cells use thin layers of amorphous silicon (a-Si).

Their key advantage? Flexibility. Silicon thin-film solar panels can be adapted to a wide range of construction needs, building types and situations. This, coupled with how easy they are to mass produce, makes them more accessible – and more affordable – than first-generation solar panels.

The drawbacks, however, are stark: less longevity and shorter warranty periods. Their lower rates of energy efficiency (around 7 to 10% currently, although this will improve as the technology advances) also mean you’ll need more space to keep them. This makes them less ideal for smaller domestic solar setups – which are naturally limited by available space and the desire to avoid a lengthy planning permission application – and better suited to larger, industrial-scale commercial solar arrays.

DSSCs

DSSCs involve absorbing dye molecules onto a semiconductor material – usually titanium dioxide – to turn sunlight into electricity.

DSSCs have several key benefits. They’re relatively cheap to manufacture and perform well even in indirect sunlight and low-light conditions. They’re also less sensitive to high temperatures than silicon-based solar panels, which makes them well suited to hot climates or environments prone to temperature fluctuations.

The trade-off is that DSSC-powered panels have lower efficiency rates than traditional silicon-based solar cells. Currently, that’s around 11%, although a lab recently reported record-high efficiency results of 14% for DSSCs.

Organic photovoltaic cells

Organic photovoltaic (OPV) cells use organic molecules or polymers as their semiconductor material. Thanks to the low-cost, solution-based processes (such as printing and coating) involved in their production, OPV cells have the potential to be an affordable, lightweight, energy-efficient and environmentally low-impact alternative to traditional solar technology.

OPV panels aren’t just easy on the wallet, either – they’re also easy on the eye. Their semi-transparent appearance makes it easier to integrate into your building’s existing design. This is crucial for seeking planning permission for your solar panels – especially if your building is listed or is part of a World Heritage Site or conservation area.

They’re also an efficient way of turning sunlight into electricity. In real-world conditions, organic solar panels have energy efficiencies of 10 to 12%; recently, under laboratory conditions, researchers have been able to extract efficiencies of up to 19% from OPV cells.

At this stage, OPV’s core drawbacks are its short lifespan and the fact that the technology is still in its relative infancy. This means that, while OPVs have plenty of promise and potential for the future, they’re not the most efficient or long-lasting solar cells on the market right now.

Third-generation solar panels represent the next phase of innovation and development in solar PV technology. Third-generation panels – which include perovskite, tandem and multijunction varieties – are defined by a focus on advanced materials, novel designs and fresh concepts to refine energy efficiency, boost cost effectiveness and improve sustainability.

Perovskite

Perovskite solar cells utilise materials with a crystal structure following the formula ABX3, which have shown increasingly promising PV properties.

Perovskite solar panels’ main benefits, at this stage, are their high (and rapidly improving) energy-efficiency rates – around 25%, with some estimates placing them as high as 35% – which give them the potential to be an extremely cost-effective solar solution.

Relatively cheap to fabricate through methods such as solution processing, perovskite solar panels can pass cost savings on to the consumer, providing that key challenges around the scalability and stability of large-scale commercial deployment can be addressed – one of which being that perovskite solar panels aren’t easy to produce on a large scale.

Other concerns with perovskite solar cells centre on their longevity. Early tests with perovskite solar panels have unearthed an issue called current-voltage hysteresis, which can have serious effects on the cells’ operating performance.

CPV and HCPV cells

CVP and HCPV systems use lenses or mirrors that act as magnifying glasses, concentrating sunlight onto small, high-efficiency solar cells. Through this technique, CPV and HCPV cells offer extremely high levels of efficiency. According to some estimates, this is as high as 41% or more – which beats out even the first generation of solar panels.

The catch? CPV and HCPV systems require near-constant exposure to sunlight to maintain such high rates of efficiency. These panels must always face the sun, meaning they require expensive, finely calibrated gear – such as tracking systems – to function properly. This makes them less suitable for domestic solar arrays and more of a solution for large-scale commercial installations.

Heterojunction technology

Heterojunction technology combines the advantages of two of the different types of solar cells we’ve already touched on: crystalline silicon (first generation) and thin film (second generation).

HJT solar panels contain heterojunctions, which are interfaces between different layers of semiconductor materials. These combine to minimise the recombination of charge carriers, reducing energy loss and boosting the cells’ overall performance and energy efficiency (typically between 24 and 26%, with a record high of almost 27%).

Among HJT cells’ other benefits are longevity and aesthetic appeal; they boast a sleek, modern and unobtrusive design ideal for buildings where planning permissionmay be required. HJT panels also boast low temperature coefficients, so they’re less vulnerable to heat-induced efficiency losses and, therefore, perform well in warmer climates.

However, HJT’s improved energy efficiency comes with a flipside: it’s expensive. HJT solar panels tend to be more complex – and therefore more costly – to produce vis-à-vis traditional crystalline silicon panels, making them less affordable for the end consumer. Because of their relative newness in the solar panel space, HJT panels will also be harder to find than their more traditional, established alternatives.

Bifacial cells

As the name suggests, bifacial solar cells have two “faces”.

Like traditional solar cells, bifacial solar cells are typically built with crystalline silicon. Unlike traditional solar cells – which absorb light from the front face alone – bifacial cells are designed to capture sunlight on both sides. This enables them to capture light reflected off surfaces such as rooftops, the ground or other nearby objects.

This design also makes bifacial panels more efficient (estimates place their efficiency at 16 to 22%) while enabling higher performance in diffuse light conditions, such as cloudy days and early mornings. Plus, you can install bifacial panels in a variety of configurations – including ground-mounted systems, elevated tracking systems or installations with reflective surfaces underneath – so they’re extremely versatile.

The flip side of this versatility is that bifacial panels demand careful planning and placement to optimise their output. They’re also more expensive than mono-facial panels due to the increased cost and complexity involved in the manufacturing process.

Half cell or cut cell

Half-cell (also known as cut-cell) solar panels use traditional-sized solar cells cut in half. This results in a pair of separate cells that are then wired together to form the solar panel, effectively creating two smaller cells out of a single, standard-sized solar cell.

This design reduces power loss from partial shading, allowing for more light absorption. Bisecting the cells also reduces the electrical resistance within them, which equates to improved efficiency and performance – currently around 20% in real-world conditions – and less loss of resistance and power.

Smaller cells aren’t as susceptible to micro-cracks and mechanical stress – making them more durable in the long run – and tend to have better temperature coefficients than full-size panels. This allows cut cells to maintain higher efficiency levels at elevated temperatures, a feature that’s particularly beneficial in hot climates.

What’s more, half-cell solar panels typically come equipped with more bypass diodes than traditional solar panels. These diodes allow electricity to flow around shaded or underperforming cells, mitigating shade-related power loss and making half-cell solar panels ideal for homes blocked off from full access to sunlight.

As with most of the higher-quality solar solutions we’ve discussed here, half-cut cells’ main downside is that they’re more expensive. The cell cutting increases manufacturing costs, which are then passed on to the customer. Half-cell modules also present challenges around wiring and configuration, which can be more difficult than with traditional cells. Another issue is the potential for cell mismatch if two halves of the same cell degrade, or age differently, over time.

Shingled solar cells

The design of a shingled solar panel takes its name from the way each cell is overlapped and interconnected with thin conductive strips, resembling the effect of shingles on a roof.

This overlapping build moves the electrical connections between cells to the panel’s rear surface, allowing for a larger active area. This, in turn, minimises shading and inactive areas on the solar panel’s front surface. By cutting the distance between each cell, this design also reduces cell-to-cell resistance and improves heat dissipation, which leads to boosted energy production and higher efficiency (around 22%) compared to traditional solar cells.

As for downsides, shingled solar cells face many of the same widespread adoption barriers as their fellow recent solar innovations: high costs, low market availability and complex manufacturing processes. Shingled solar cells may also be more prone to “hot spots” – localised, longevity-limiting blots that happen when certain cells in the panel receive more sunlight than others. Hot spots can reduce your solar cells’ efficiency and limit their lifespan.

To find out which type of solar cell is right for your home, dive into the table below: you’ll find summaries of the benefits and drawbacks of each, along with a rundown of where each different type of solar cell will thrive.

There are several factors you should consider when choosing solar panels, including how much you want to spend, how much space you have to place your solar panels and how efficient you need your domestic solar array to be.

Cost

When it comes to how much solar panels cost, all types are not created equal. And, as with most products and services, it’s typically a case of getting what you pay for.

Generally, higher-quality solar panels – those with more impressive efficiency, low-light performance and adaptability to temperature fluctuations – will always cost more than those at the opposite end of the performance spectrum.

You can also expect to pay more for emerging solar cell and panel technologies, such as perovskite, HJT, bifacial, half-cell and shingled solar solutions. In these cases, the higher prices are tied more to their nascent nature and limited availability. As these technologies improve, proliferate and enter the mainstream over time – and as the clamour and demand for solar panels in the UK continues to rise – they should become cheaper.

Available space

The type of solar panel that’s right for your home will, naturally, depend on the amount of available space you have to work with.

Higher-efficiency solar panels – such as monocrystalline or those of the more recent HJT, perovskite and bifacial varieties – are also more space-efficient. Because they’re better at turning the sun’s rays into renewable electricity, these panels require less space to generate the same amount of energy as a less-efficient solar setup.

This is why lower-efficiency varieties, such as thin-film silicon solar panels, tend to be more popular in large-scale industrial developments, where panels are affordable and available space is less of an issue. With small-scale domestic arrays, however, space for solar panels is often at a premium, and high-efficiency types of solar cells are a must.

Planning permission

Closely related to the issue of size is the factor of planning permission – more specifically, whether you’ll need to apply for it to get your domestic solar setup off the ground.

Or, for that matter, on the ground: if you’re planning on ground-mounting your solar panels, they must not exceed a nine-metre square area and must be no higher than four metres. The rules for rooftop-based installations are a bit more relaxed, but they’re still not allowed to project more than 20cm (for slanted roofs) or 60cm (for flat roofs) above your roof’s ridgeline.

Therefore, if you want to avoid the six- to eight-week process of the planning permission application (plus all the time-consuming document-gathering and cost that goes with it), you’ll need to keep your home solar setup within a specific size. This, in turn, will require you to opt for more efficient solar panel types, such as monocrystalline solar panels, to maximise your array’s electricity output.

Ultimately, there’s no objectively “best” type of solar panel – only the best type of solar panel for you. As we’ve seen, this depends on how much space, and how much budget, you have to work with, as well as factors such as the placement and positioning of your panels.

However, if we had to choose the best type of overall solar panel – weighing up factors such as availability, performance and efficiency against cost – we’d pick monocrystalline solar panels. These first-generation solar panels synthesise low-light performance with energy and space efficiency – even at high temperatures – while boasting a distinctive, durable design to showcase that, sometimes, the oldies really are the goodies.

Monocrystalline solar panels are more expensive, but their ability to turn sunlight into clean, green electricity for your home means they’ll repay your initial investment in a matter of years. (You can find out just how many years that may be in our guide to how solar panels pay back.)

This efficiency is more than either polycrystalline or thin-film solar panels can claim and comes with none of the novelty or availability problems of third-generation solar panels and beyond. Plus, because monocrystalline panels are so energy efficient, you’ll need fewer of them to power your home. This is crucial for sticking to the size and scale requirements you’ll need to comply with to avoid having to apply for planning permission; it also means you’ll need less space to furnish your home’s roof or garden with a strong solar setup.