A Complete Guide to Solar Panel Efficiency: Most Efficient Solar Cell, Top-Performing Panels, and Beyond

olar power has been gaining traction as a promising alternative energy source for decades now, with its ability to harness the endless supply of energy from the sun. However, for those who are not well-versed in the field of renewable energy, the technicalities of solar panels may seem daunting. One of the most crucial factors to consider when it comes to solar panels is their efficiency. But what does it really mean for a solar panel to be efficient, and what maximum efficiency of solar panels should homeowners be looking for? In this article, we'll explore the ins and outs of solar panel efficiency and why it matters.

What is solar panel efficiency?

Let's begin by defining solar panel efficiency. Essentially, it measures how well a solar panel can harness sunlight and convert it into usable electrical energy. This is a crucial consideration when choosing solar panels since higher efficiency panels can generate more electricity from the same amount of sunlight than lower efficiency ones. Solar panel efficiency is typically expressed as a percentage, representing the proportion of sunlight that the panel can convert into electricity. For example, a solar panel with an efficiency rating of 20% can transform 20% of the sunlight it receives into electrical energy.

Tracing the progress of solar panel efficiency: How efficient were the first solar panels?

The history of solar dates back to the 19th century when French physicist Alexandre-Edmond Becquerel discovered the photovoltaic effect in 1839. However, practical solar cells similar to those we use today weren't developed until the 1950s by Bell Labs in the United States. These early solar cells had an efficiency of only 4%, meaning they could only convert 4% of the sun's energy into usable electricity, which was a significant improvement from previous experiments but not yet efficient enough for widespread use.

During the 1970s, advancements in technology and increased government funding led to a significant increase in the efficiency of solar panels. By the end of the decade, solar panels could achieve efficiencies of around 14%, which was considered a breakthrough. Nevertheless, these solar panels were expensive and mainly used for space exploration and remote power applications. But as the cost of solar technology continued to decline and efficiency continued to improve, solar panels became more widely used for powering homes and businesses.

Over the years, there have been many technological advancements in solar panel manufacturing, which have led to significant improvements in efficiency. The average efficiency of solar panels today falls within the range of 16% to 20%, with panels exceeding 20% classified as the most efficient.

What is the most efficient solar cell today?

While the 20% efficiency of present-day solar panels is remarkable compared to their predecessors, it's worth noting that this efficiency rate is what's commonly found in residential solar panels available in the market. The efficiency of individual solar cells in laboratory conditions is nearly twice as high.

A new world record for solar cell efficiency was set in 2022 by researchers at the US Department of Energy's National Renewable Energy Laboratory (NREL), with an impressive 39.5% under lighting conditions similar to those of the sun. Earlier solar experiments have managed to reach an efficiency of up to 47.1%, but this efficiency level was only attainable under extremely concentrated light.

Can solar panels ever achieve 100% efficiency?

So can we potentially create a solar cell with 100% efficiency? Unfortunately, it's not possible due to the nature of semiconductor materials, which are the only viable materials for harnessing solar power. Semiconductors cannot absorb the entire solar spectrum, so most of the light that hits the surface of the panels cannot be efficiently converted and is lost as heat in the material. The Shockley-Quessier Theory of solar efficiency places a hard cap of 68% on potential performance, which is still far from being reached by scientists and manufacturers.

Which solar panel type offers the highest efficiency?

Three primary kinds of solar panels are available today: monocrystalline, polycrystalline, and thin-film. Out of these options, monocrystalline solar panels tend to be the most efficient. They are constructed from a single silicon crystal and boast maximum solar panel efficiency rates as high as 16% – 24%, making them an excellent choice for residential and commercial projects where space is at a premium.

Polycrystalline solar panels are another popular type, and they are less expensive than monocrystalline panels. Nonetheless, they have a marginally lower efficiency range of 14% – 20%. These solar panels are composed of various silicon crystals, making them less efficient in converting sunlight into electricity. Generally, they're a decent option for larger solar installations where cost is the primary consideration.

When compared to monocrystalline and polycrystalline panels, thin-film solar panels have lower efficiency of 10% to 13%. However, their lightweight and flexible design makes them ideal for portable applications like tents and cars. They are also more economical to produce, which makes them an affordable solar alternative for certain applications.

Maximum solar panel efficiency vs. real-life solar panel efficiency

Manufacturers evaluate solar panel efficiency by testing them under Standard Test Conditions (STC), which entail a temperature of 25°C and an irradiance of 1,000 W/m2. These conditions simulate a sunny day with the light hitting a sun-facing 37°-tilted surface. However, real-world scenarios seldom match these optimal settings, and the efficiency of solar panels in practical use depends on various external factors that we'll delve into in the following section.

Factors affecting solar panel efficiency

Let's examine the primary factors that influence the efficiency of your PV modules in practical settings. By doing so, you will learn how to avoid the most frequent efficiency roadblocks.

Solar panel type and quality

Naturally, the efficiency of a solar panel is influenced by the type and quality of the panel itself. There are different types of solar modules available in the market, such as monocrystalline, polycrystalline, and thin-film, each with its own unique characteristics that affect their efficiency. Additionally, the quality of the materials used to manufacture the solar panel plays a significant role in determining its efficiency. High-quality panels made with superior materials are often more efficient and durable than lower-quality ones.

Temperature

It may seem paradoxical, but as temperatures increase, solar modules become less efficient due to the excess heat - it causes electrons to move faster, decreasing the amount of solar energy that can be harnessed and utilized. Improving the efficiency of solar panels requires taking into account the impact of temperature and taking steps to minimize the negative effects of excessive heat, such as designing, installing, and maintaining solar panels correctly.

Shading

Solar panel efficiency can be significantly impacted by shading. The potential energy output of a solar panel is adversely affected when it's in the shade, as it can efficiently absorb only a limited amount of sunlight. In fact, the efficiency of an entire panel can be impacted by a single shaded solar cell, resulting in zero output. Shading can occur due to a variety of reasons, including nearby structures, trees, and clouds.

Dirt and dust on panels

Solar panels generate electricity by absorbing sunlight, but their ability to do it efficiently can be diminished by the buildup of dirt and dust on their surfaces. In addition, shadows formed by accumulated debris can further reduce their efficiency. Therefore, to achieve optimal efficiency from solar panels, it's important to clean them regularly and remove any dirt or debris.

Solar panel angling and orientation

For maximum efficiency, solar panels should ideally face south (in the northern hemisphere) or north (in the southern hemisphere) during installation. Moreover, the angle of the solar panel should match the latitude of the installation site to optimize energy absorption. Even a slight deviation from the recommended angle or orientation could result in reduced solar efficiency, lower energy output, and longer payback time.

Panel degradation over time

The elements can cause wear and tear to solar panels, which can reduce their overall efficiency. As a result, the power output of the panels decreases, leading to a reduction in the overall energy yield. Therefore, proper maintenance, cleaning, and monitoring are necessary to ensure optimal efficiency and long-term performance of solar panels.

Top 5 most efficient solar panels

Many leading companies in the solar panel industry are vying to create the most efficient solar panels, resulting in a constant stream of new and innovative products each year. Now, let's explore the top-rated solar panels that homeowners can currently purchase to maximize their energy efficiency.

SunPower Maxeon 6 – 22.8% efficiency

Since the debut of their IBC solar technology in 2007, SunPower has been hailed as the preeminent manufacturer of solar panels with exceptional efficiency. Today, under the name Maxeon Solar Technologies, SunPower continues to produce the most efficient solar panels in the market by leveraging their patented IBC technology. This innovation shifts all the front contact grids to the rear side of the solar cell, resulting in unparalleled efficiency.

In 2022, SunPower unveiled their most advanced solar panel offering to date - the Maxeon 6 range, also referred to as the M-series in North America. With a 66 cell format and a peak power rating of 440W, these panels utilize the next-gen Maxeon 6 cells to achieve the highest efficiency rating of 22.8%, setting a new efficiency benchmark for solar panels designed for residential use. Furthermore, the A series version of the Maxeon 6 solar module has the added convenience of incorporating a highly efficient Enphase microinverter, which makes it an excellent option for those who prefer purchasing solar panels and inverters in one go.

LONGi Solar Hi-Mo 6 –22.8 % efficiency

LONGi has established itself as the dominant force in the solar industry, holding the largest market share since 2020. As a manufacturer of solar products ranging from wafers to cells and panels, LONGi has played a pivotal role in advancing the industry's pursuit of more efficient PERC technology. By incorporating an additional layer of glass onto the backsheet of solar cells, PERC, or "passivated emitter and rear contact," panels have boosted the solar cell efficiency, allowing them to capture and convert more of the sun's rays into usable electricity.

In late 2022, LONGi revealed their newest high efficiency PV modules, the Hi-MO 6, featuring an innovative HPBC technology (Hybrid Passivated Back Contact). The uniqueness of this solar cell technology lies in its front-side busbar-free design, enabling an impressive panel efficiency rate of 22.8%, comparable to Sunpower's efficiency. These solar panels offer a power rating ranging from 410W to 600W, accompanied by a 15-year product warranty and a 25-year performance warranty.

SunPower Maxeon 3 - 22.7% efficiency

SunPower's leading range of solar panels includes Maxeon 3, which is available in sizes ranging from 400 to 430W, offering a space efficient option for residential setups. The Gen 3 level solar cells used in the Maxeon 3 series contribute to its remarkable 22.7% maximum efficiency rate, making it one of the most efficient solar panels currently available.

What's more, the Maxeon 3 solar panels have one of the most remarkable power output drop rates in the market. SunPower guarantees that even after 25 years, the panels will still produce 92% of their initial power output, making them 35% more efficient than traditional home solar panels.

Canadian Solar HiHero - 22.5% efficiency

Founded in 2000, Canadian Solar has undergone tremendous growth to become one of the top five solar panel module manufacturers worldwide. The company’s range of products includes efficient solar panels, raw silicon ingots, wafers, and solar cells, which ultimately help reduce production costs.

One of the most efficient solar panels produced by Canadian Solar is the HiHero, which employs N-type HJT (heterojunction) PV technology and boasts an impressive efficiency rate of up to 22.5%. To put HJT technology in simpler terms, the solar cell is built by layering three different photovoltaic materials to achieve an efficiency level that rivals the most efficient solar panels on the market. With a power range of 415W to 440W, the HiHero is an ideal option for both commercial and residential installations.

REC – Alpha Pure-R –22.3% efficiency

REC Group, founded in Norway in 1996, is a leading manufacturer of solar photovoltaic modules known for their top-notch quality and efficiency. Their solar panels are distinguished by their innovative half-cut technology, which REC introduced in 2014. This efficient design maximizes the energy output of solar panels by shrinking the size of solar cells, allowing more to fit on each panel. Half-cut technology has enabled REC to produce solar panels with exceptional wattage and efficiency, resulting in greater solar power per square foot.

In 2000, REC introduced the REC Alpha Pure-R Series, the next generation of its high efficiency solar panels for residential rooftops. The Alpha Pure-R model has 80 half-cut HJT cells with G12 solar wafers in a gapless design and can generate up to 430 W of power with an impressive efficiency rate of 22.3%. Moreover, this model is perfect for homes that lack space for solar panels. Despite its remarkable efficiency and output, it is lightweight at 47.4 lb and occupies only 20.77 square feet.

Does solar panel efficiency really matter when choosing solar panels?

When you're thinking about solar panels, efficiency is a crucial aspect to keep in mind. The higher the efficiency of a solar panel, the more energy it can generate from the same amount of sunlight. This is especially essential if you have limited space for your solar panels because higher efficiency panels can produce more power per square foot than lower efficiency ones. In addition, solar panels with increased efficiency can be more cost-effective over time since they can generate more electricity throughout the system's lifespan.

However, it's crucial to strike a balance between efficiency and cost when selecting solar panels, as higher efficiency options are usually more expensive. In many cases, the difference in power output between highly efficient and less efficient solar panels may not justify the additional expense. Hence, it's critical to evaluate all factors when selecting solar panels to ensure that you choose the ideal option for your specific needs and situation.

Final thoughts on solar panel efficiency

Over the years, solar panel technology has made significant strides, resulting in remarkable improvements in efficiency rates. Today, the market boasts some of the most efficient solar panels, like SunPower and LONGi, which offer maximum solar panel efficiency rates of up to 22.8%.

The efficiency of solar panels is a critical aspect in determining the cost-effectiveness of a solar system since panels with higher efficiency rates can generate more electricity from the same amount of sunlight than lower efficiency ones. However, it's worth noting that although solar efficiency is an important consideration, it's not the only one. Other factors like cost, space, and quality should also be evaluated to ensure the best outcome for your needs.