Most Efficient Solar Panels: A Comprehensive Guide to Solar Panel Efficiency

nstalling solar panels is a big step toward sustainable living and low electricity costs. Households with solar panels have a huge advantage in saving money on energy bills: with a correctly sized solar panel system, you can reduce your bill by up to 90%. However, the benefits of residential solar panel systems do not end there, as photovoltaic panels also increase property value, provide energy independence, and dramatically cut individual carbon footprint.

If you plan to have your home outfitted with solar panels, you naturally want to get the most out of your investment. While the temptation may be to opt for cheaper offerings, buying high performance solar panels is the surest way to maximize ROI and yield the best long-term results of heyco.

You're probably full of questions at this point. What does solar panel efficiency even mean? Why does it matter? What high efficiency solar panel is the best? This article has all the answers for you!

What is solar panel efficiency? Understanding solar efficiency rate

To understand solar efficiency, let’s take a closer look at how photovoltaic panels work. As you no doubt already know, solar panels generate electric power by collecting sunlight. When the sun’s rays hit the surface of a solar panel, they trigger the photovoltaic effect – the phenomenon in which electrical current is created within a material when exposed to electromagnetic radiation.

Each solar panel consists of smaller units called solar cells. When photons (particles of light) come in contact with the cells, they knock electrons within them loose from parent atoms. An electromagnetic field forces the electrons to move through the circuit generating an electric current.

And that takes us to the definition of solar panel efficiency. Unfortunately, solar panels can’t efficiently convert all the sunlight falling on their surface into electric power (we'll examine some of the reasons for that later.) The efficiency of a solar panel (also called efficiency rate) is the amount of solar irradiation that reaches its surface and is converted into electricity.

What makes a high efficiency solar panel?

Now, let's quickly go over the critical factors that determine solar panel efficiency and see what requirements a high efficiency solar panel has to meet.  

High efficiency of solar cells constituting a PV panel

The first condition for manufacturing a high efficiency solar panel is efficient solar cells. Solar cells made today are not fundamentally different from those used in PV panels half a century ago: most of them are still made of silicon, and all of them use the photovoltaic effect to produce usable energy. Nevertheless, some modifications to their structure made by scientists over the years helped dramatically improve solar panel efficiency. So generally, a high efficiency solar panel requires efficient solar cells before anything else.

Efficient cell layout and configuration within a panel

Efficiently arranging solar cells in a panel also plays a highly important role in solar panel efficiency. In attempts to squeeze out more from traditional solar panels and magnify PV panel efficiency rate, scientists rethink and restructure conventional solar cells and panels to remove as many limits to their conversion efficiency as possible.

One example is the placement of busbars - thin metal ribbons printed on solar cells responsible for efficiently conducting DC power generated by the cells. The standard solar panel design involves 2 or 3 busbars on one cell, but the solar panel market increasingly shifts towards newer and more efficient multi-busbar technology. The increased number of busbars efficiently reduces each busbar’s current and minimizes the resistive losses of the panel, which boosts the solar panel efficiency by up to 0.5 %abs.

Other factors affecting solar panel efficiency

Generally, every solar panel component can affect its efficiency and performance. For example, the color of a backsheet has a hand in how much sunlight a solar panel efficiently collects. While black backsheets for PV panels are more aesthetically pleasing, they absorb more heat; and the hotter solar panels get, the less efficient they become. So if you look for a high efficiency solar panel, you will most likely have to sacrifice some of the aesthetics and opt for panels with white backsheets.

Solar panel efficiency is impacted by external factors such as irradiance levels and air temperature. These efficiency factors deserve a separate overview, but we will save that for another time.

For ease of comparison, all solar manufacturers rate solar panel efficiency under Standard Test Conditions (STC) that imply 1,000 Watts per square meter solar irradiance, 25 degrees C solar cell temperature, and 1.5 air mass. That being so, the solar panel efficiency we mention in this article is measured under STC.

How efficient are solar panels today?

Before answering this question, it needs to be clarified that the efficiency of a solar panel does not equate to the efficiency of the solar cells it comprises. While an average high watt solar panel has a conversion rate of around 21-22%, some state-of-the-art solar cells are over 40% efficient. The world record for solar cell efficiency currently stands at 47.6%, which is highly impressive. However, one should keep in mind that the efficiency of solar cells is measured under laboratory conditions, which are entirely different from real life.

What efficiency rate can a solar panel potentially reach?

Solar panel efficiency ratings keep rising yearly, so does this mean it won't be long before solar panels become 100% efficient? Well, unfortunately, even a high efficiency solar panel will never be able to efficiently absorb and convert all the solar irradiance into electricity. To understand why that is the case, we must discuss the solar band gap concept.

The energy band gap is the minimum energy needed to excite the electrons within a substance so that they can break loose from the parent atoms. Most conductors, such as metals, have zero band gap, meaning they always have free electrons which can move freely through the material. Insulators, on the contrary, have high band gaps, which means their electrons require very high energy to jump free of their parent atoms. Therefore, the most suitable materials to efficiently harvest the sun’s power with solar panels in terms of a band gap are semiconductors, as their bandgap of around 1.4 eV is the most efficient for solar panel manufacturing.

However, the sun emits photons in a broad range of energies, from low energy infrared light through visible light to high energy ultraviolet light. Unfortunately, no single semiconductor used for PV panel manufacturing can efficiently capture the entire spectral range. According to the Shockley–Queisser efficiency theory, the upper limit for solar efficiency is 33.7% for a single-junction solar cell. To address this efficiency limitation, the researchers designed multi-junction solar cells, e.g., cells containing different materials with considerably different band gaps. Thanks to that approach, the efficiency of solar cells is steadily approaching 50%.

But even the most powerful solar panel can’t reach 100% efficiency, as some portion of the energy is inevitably lost. In fact, no energy transformation process is completely efficient, as stated by the second law of thermodynamics. Nevertheless, considering the powerful leap solar panel efficiency has made over the decades, it will most likely continue to soar high.

Monocrystalline vs. polycrystalline solar panels: which are more efficient?

Now let’s move on to more practical matters and discuss how to find a high efficiency solar panel. The overwhelming majority of panels sold today are made from crystalline silicon, but not all c-Si panels are created equal. They fall into two types: monocrystalline panels and polycrystalline panels. Below, we discuss what type you should opt for when looking for a high power solar panel.

Monocrystalline solar panels: more efficient but highly priced

Monocrystalline panels are characterized by black solar cells with rounded edges. These cells are manufactured using the Czochralski method, in which a tiny silicon crystal is placed into a crucible with molten silicon and then gradually pulled upwards to obtain a single large crystal. This cylindrically-shaped crystal called an ingot is later sliced into thin discs serving as a base for solar cells.

When looking for a high efficiency solar panel, a monocrystalline model is the optimal choice. Mono-Si panels have rather high efficiency rates, usually in the 18-22% range. This leads to the next advantage: a high efficiency solar panel generates more power per square foot and is, therefore, more space efficient. Additionally, monocrystalline solar panels demonstrate high efficiency rates in hot weather: while solar panel production always drops at high temperatures, mono-Si solar panels offer minimal power losses.

But there is another side of the coin: the cost of efficient monocrystalline panels is relatively high. However, remember that a high efficiency solar panel will save you more money in the long run.

Polycrystalline solar panels: cheaper but fall short in efficiency

Polycrystalline solar panels can be distinguished by dark blue solar cells with straight edges. Unlike monocrystalline solar cells made from one large crystal, polycrystalline cells are manufactured from multiple silicon fragments melted in an oven and poured into a cube-shaped cast.

A poly-Si module delivers only about 15 to 18% efficiency, so this option won’t suit those who are looking for a high efficiency solar panel. Additionally, polycrystalline solar panels have lower heat tolerance than efficient monocrystalline panels, meaning they perform worse in high temperatures. On top of it, poly-Si panels are less efficient in low-light conditions.

The main advantage of polycrystalline solar panels is their cost. They are around 20% cheaper to manufacture, which leads to a lower price tag. An average polycrystalline panel typically costs about $0.05 per watt less than a high power solar panel made of monocrystalline silicon.

Solar power technologies allow the manufacturing high efficiency panels

Solar research keeps making impressive strides. Over the last few years, engineers have developed some highly promising technologies to boost solar panel efficiency. We’ll take a look at some of them below.

IBC cells

Currently, the most efficient solar panels are manufactured using IBC (Interdigitated Back Contact) monocrystalline solar cells. When fabricating conventional solar panels, manufacturers add thin metallic lines onto the front and back surfaces of the cells. The primary purpose of these grid-like contacts is to efficiently collect and deliver energy to the busbars. IBC configuration positions all the contacts on the cell’s rear, leading to significantly lower shading losses and, consequently, high efficiency. Another advantage of this efficient solar cell architecture is that IBC cells are easier to interconnect and place right next to each other in the panel since there’s no need for any gaps between them.

IBC solar cells have already reached efficiency rates of as high as 27% and have the potential to hit 29.1% shortly. This configuration is already actively working its way into the solar panel market; for example, a leading PV panel company SunPower uses IBC technology in Maxeon 6 – their flagship high efficiency solar panel.

Heterojunction (HJT) cells

Another highly efficient solar power technology widely adopted in the PV panel industry is heterojunction (HJT) solar cells. Basically, it is a combination of two established technologies, where the crystalline silicon layer is sandwiched between “thin-film” layers of amorphous silicon. This three-layer combination allows solar panels to efficiently capture as much solar power as possible.

Heterojunction technology achieved a remarkable efficiency of 26.7%, while bifacial HJT cells even managed to surpass 30%. Most residential HJT panels on the PV panel market have efficiencies ranging from 20% to 22%, which is a considerable improvement compared to the efficiency of traditional monocrystalline panels. Additionally, these efficient heterojunction models offer decent high temperature performance and comparatively low panel manufacturing costs.

Top solar panel manufacturers, such as REC, Canadian Solar, and Panasonic, produce efficient HJT solar panels.

TOPcon cells

TOPcon (tunnel oxide passivated contact) solar cells are a novel technology in the PV panel market based on the highly efficient charge carrier-selective principle. These cells use an ultra-thin tunnel oxide layer in combination with a thin silicon layer to enhance electrical conductivity. This results in exceptionally high conversion efficiency and increased PV panel power production. Additionally, compared to heterojunction technology, adding one oxide layer to a conventional solar cell represents an easier and cheaper manufacturing upgrade, so the costs of TOPcon panels aren’t too high.

Passivated contact PV panel technology is growing in popularity, embraced by such solar market trendsetters as Trina Solar, LONGi, and Jinko Solar.

Why is getting a high efficiency solar panel worth it?

The efficiency difference between two random solar panels on the market rarely goes beyond 5%, which doesn’t look like much. So is a high efficiency solar panel really worth paying extra?

First, remember that it is always better to prioritize the quality of a solar system. While the idea of getting highly efficient panels for less money may seem appealing, solar shoppers who are on a tighter budget should opt for market-proven high quality panels, albeit slightly less efficient.

But at the same time, a high efficiency solar panel means you will need fewer panels to meet your home’s electricity demands. So carry out a thorough calculation to see what PV panel setup will be more cost efficient in your case.

Additionally, a high power solar panel can be an ideal choice if you have space constraints: such panels allow you to pack maximum efficiency onto a limited rooftop space. Choosing high efficiency panels also makes sense if your roof doesn’t face true south because they’ll help increase power output. And finally, if money is not an issue and you simply want the most efficient solar panel available, go right ahead! Below, we offer you a list of high performance solar panels to choose from.

Choosing high efficiency solar panel. Top 5 most efficient solar panels

The solar power market is crowded with PV panel offerings, and everybody can find efficient solar panels that suit their needs and budget. Every leading PV panel manufacturer seeks to create their own high efficiency solar panel, so the industry is highly competitive. We’ve put together a list of top products that deliver high efficiency and performance. Note that commercial solar panels often boast higher efficiencies than residential ones. Here we focus on efficient solar panels designed mainly for residential use, so this list includes only panels with a solar power rating of up to 430W.

SunPower Maxeon 3

SunPower is considered a high technology solar services provider that offers the most efficient solar panels on the market. Founded in 1985, the California-based company produces a complete line of highly efficient residential, commercial, and utility-scale solar equipment, including solar panels, solar inverters, and solar mounting systems.

The most efficient solar panels released by SunPower are the Maxeon series. Maxeon 3 is a flagship panel available in power ratings from 370 to 400W that is perfectly suitable for residential applications. This 104-cell high efficiency solar panel uses IBC N-type solar cell technology and offers a remarkable 22.8% maximum efficiency rate, making it the world’s most powerful solar panel.

The Maxeon 3 panels have one of the lowest degradation rates in the solar panel market. SunPower guarantees that a 25-year-old panel will produce 92% of the initial output. The company provides a comprehensive 40-year product and performance warranty.

REC Alpha Pure R

REC Group is a global solar panel manufacturer headquartered in Singapore. The company is a fully integrated panel supplier, controlling all the stages along the supply chain, including ingots, wafers, solar cells, and panel assembly.

REC is one of the solar industry’s top innovators that offers one of the most efficient solar panels. The company pioneered the manufacturing of solar panels with half-cut cells instead of full-size ones, which helped create highly efficient solar panels.

The Alpha Pure R series is the latest high efficiency solar panel released by REC. The panel boasts 80 half-cut HJT cells and a power rating reaching 430W. Alpha Pure R is one of the top offerings on the solar panel market in terms of efficiency, demonstrating a 22.3% efficiency rate. The high power solar panel also boasts an exceptionally high temperature coefficient, making it a perfect choice for hot climates.

A 25-year product and power warranties for a panel guarantee 92% solar output after 25 years.

Q Cells Q.TRON

Q cells is one of the world´s most recognized solar panel manufacturers. Originally a German company, it was established in 1999 and acquired by South Korean conglomerate Hanwha Group in 2012. Today Q cells is based in Seoul and has PV panel production facilities in China, South Korea, and Malaysia.

The company manufactures a wide range of highly efficient photovoltaic panels designed for various applications. Q Tron series is Q Cells’ most popular high efficiency solar panel for domestic use. The latest Q.Tron-G1+ panel features mono PERC half-cut multi-busbar solar cells and delivers up to 400W power. The zero-gap PV cell layout brings the panel efficiency to 22.3% - one of the top rates in the industry.

This high efficiency solar panel comes with a 25-year product warranty and a 25-year performance warranty. The company promises that 25-year end power will not decrease by more than 90.58% of the nominal power.

Panasonic EverVolt

Founded in 1918, the Japanese electronics manufacturer announced its foray into the solar panel market in 1975. Initially, Panasonic focused on the fabrication of efficient thin-film solar panels, also called flexible solar panels. However, in 1997, the company took an interest in a new type of solar panel with HIT cells (Heterojunction with Intrinsic Thin layer). The efficient solar cells used in Panasonic solar panels combine both crystalline and amorphous silicon solar panel technologies. This results in a high bandgap allowing the solar panels to efficiently collect more sunlight and generate more power.

The company’s most efficient residential panel series EverVolt utilizes half-cut HIT solar cells and has a power output ranging from 400 to 410 W. The 410W high efficiency solar panel offers an excellent efficiency of 22.2%, which makes them one of the top solar offerings.

Thanks to the half-cut HIT technology, EverVolt works excellently at high temperatures: it boasts one of the lowest temperature coefficients among residential panels, just about -0.26%, while the majority of solar panels on the market have between -0.3% and -0.5%. The efficient EverVolt panels are said to be able to deliver 92% of their original power production at the end of the guarantee period, which is 25 years for both product and performance.

Trina Solar Vertex S+

Established in 1997, Trina Solar pioneered China's solar panel industry. Today the company is one of the world’s most reputable solar panel manufacturers and solar solution providers operating in North America, Asia, and Europe. Trina Solar specializes in highly efficient crystalline silicon photovoltaic panels, offering a comprehensive product range for residential and large-scale use.

Vertex S+ is by far Trina’s most efficient and leading-edge panel designed for residential rooftop applications. It generates up to 425W power, achieving 21.9% panel efficiency with high density cell interconnection. The product uses a double-glass panel design instead of the conventional backsheet with tempered glass; such an efficient structure boosts heat resistance and improves the durability of the panel. The Vertex S+ high efficiency solar panel comes with a 25-year product and 30-year performance warranty.

Sources:

https://www.pv-magazine.com/2022/05/30/