Sep. 08, 2025
Solar panel efficiency is the amount of sunlight (solar irradiance) that falls on the surface of a solar panel and is converted into electricity. Due to the many advances in photovoltaic technology over the last decade, the average panel conversion efficiency has increased from 15% to over 24%. This significant jump in efficiency resulted in the power rating of a standard residential solar panel increasing from 250W to over 450W.
As explained below, solar panel efficiency is determined by two main factors: the photovoltaic (PV) cell efficiency, which is based on the solar cell design and the type of silicon used, and the total panel efficiency, which is based on the cell layout, configuration, and panel size. Increasing the panel size can improve efficiency by creating a larger surface area to capture sunlight, with the most powerful solar panels now achieving power ratings of over 700W.
At present, silicon-based monocrystalline panels are the most efficient type available. However, modern monocrystalline panels are manufactured using several different cell types, with the most efficient varieties utilising high-performance N-type cells, which enable panels to reach efficiencies above 24%. The three main variations of N-type cells are heterojunction (HJT), TOPcon, and back-contact (BC), which are described in detail below.
Featured content:Want more information on 60 Cell Solar Panel? Feel free to contact us.
Polycrystalline cells and panels are no longer manufactured due to their lower efficiency, which peaked at just over 18%. In recent years, virtually all leading solar panel manufacturers worldwide have transitioned to producing more efficient solar panels using N-type HJT, TOPcon, or Back-contact cells. Learn more about solar PV cell construction and the different cell types.
For the second year running, Aiko Solar holds the top spot in residential solar panel efficiency rankings with the release of its third-generation NEOSTAR 3P54 series, launched in mid-. This next iteration of ABC (All Back Contact) modules features near-gapless cell spacing and repositioned string connectors for improved layout and performance. The result is a significant efficiency boost, with the new series achieving up to 24.8% module efficiency, up from 24.3% in the Gen 2 series.
Maxeon, formerly SunPower, the long-time efficiency leader, is set to reclaim the top position later in with the upcoming Gen 8 (Maxeon 8) series. While not yet officially released, the new generation is expected to feature a completely redesigned cell architecture, larger wafers, and a module efficiency exceeding 25%. Maxeon’s current Gen 7 modules, launched in –, offer efficiencies up to 24.1%.
LONGi Solar is now also pushing the 24% efficiency boundary with the advanced Hi-MO X10 modules featuring the second-generation HPBC (2.0) back-contact cell technology. However, another 54-cell bifacial premium module, the recently announced EcoLife series, is set to be commercially available from late , rated for up to 25% efficiency and a maximum output of 510W, which could solidify LONGi's position as a leader in the industry.
Jinko Solar remains a strong contender, with its Tiger Neo series offering efficiencies up to 23.8% and a 515W output. Recom Tech’s Black Tiger series also remains competitive at 23.6%, while LONGi’s earlier Hi-MO 6 ‘Scientist’ series — using HPBC (Hybrid Passivated Back Contact) cells — helped the company first breach the 23% mark in residential modules. Other leading manufacturers, including Canadian Solar, REC, Huasun Solar, and SPIC have released high-efficiency modules using heterojunction (HJT) cells, with several nearing or exceeding 23.5% efficiency.
Meanwhile, several commercial and utility-scale modules are now reaching even higher efficiencies than their residential counterparts. For example, LONGi’s Hi-MO X10 commercial-size module reaches up to 24.8% efficiency and 670W output, while several 700W+ utility-scale modules from Trina Solar, Risen, TW Solar, and Huasun now exceed 24.2–24.8% efficiency, highlighting how innovation at the large-format level continues to raise the bar for the entire industry. For a detailed breakdown of the latest large-format, high-output panels, see our companion article: The Most Powerful Solar Panels.
Cell efficiency is determined by the cell structure and type of substrate used, which is generally either P-type or N-type silicon, with N-type cells being the most efficient. Cell efficiency is calculated by what is known as the fill factor (FF), which is the maximum conversion efficiency of a PV cell at the optimum operating voltage and current. Note cell efficiency should not be confused with panel efficiency. The panel efficiency is always lower due to the internal cell gaps and frame structure being included in the calculated area. See further details below.
The cell design plays a significant role in panel efficiency. Key features include the type of base silicon substrate, busbar configuration, and passivation type. Panels built using back-contact (IBC) cells are currently the most efficient (up to 24.8%) due to the high-purity N-type silicon substrate and no losses from busbar shading. However, panels developed using the latest N-Type TOPcon and advanced heterojunction (HJT) cells have achieved efficiencies above 23%.
Tandem Perovskite cells are widely regarded as the next-generation PV cell technology predicted to enhance or even overtake silicon as the primary material for PV cells. While cell efficiency levels have reached recording breaking levels of over 30%, Perovskite cell technology is still under development and not expected to become commercially viable for another year or two. However, one company, Oxford PV, who holds the record for the most efficient commercial-sized perovskite-on-silicon tandem solar panel at 26.8%. In September , Oxford PV secured a commercial deal to deliver panels with an efficiency of 24.5% to an undisclosed US company for small utility-scale project. It is unknown when Oxford PV will further scale up the manufacturing of the perovskite tandem cells for mass production or limit use to verify and prove commercial viability.
The most significant barrier to Perovskite cells is their reduced lifespan due to cell instability and degradation. Fortunately, companies and scientific institutions worldwide are overcoming these problems with frequent breakthroughs, resulting in reduced degradation and longer life. Once the issues are overcome and the technology becomes commercially viable, panels built using multi-junction Perovskite-coated silicon cells are expected to achieve efficiency levels well over 27% and possibly nearing 30% by .
With new PV cell innovations happening every few months, the rapid pace of technology makes it difficult to keep track of the latest advancements, even for those working in the industry. Fortunately, several leading institutions monitor progress and publish the latest findings. NREL produces a great interactive chart of the highest confirmed conversion efficiencies for PV cells from the world’s leading researchers. Additionally, Progress in Photovoltaics publishes listings of the latest PV cell technologies twice a year - Version 64 of the efficiency tables was released in July and is free to read. The latest version 65 of Solar cell efficiency tables, released in November , is now available but requires a login or payment.
In environmental terms, increased efficiency generally means that a solar panel will pay back the embodied energy (the energy used to extract the raw materials and manufacture the solar panel) in a shorter period. Based on detailed lifecycle analysis, most silicon-based solar panels repay the embodied energy within two years, depending on the location. However, as panel efficiency has increased beyond 20%, payback time has reduced to less than 1.5 years in many locations. Increased efficiency also means a solar system will generate more electricity over the solar panel's average 20+ year lifespan and repay the upfront cost sooner, resulting in an improved return on investment (ROI).
Solar panel efficiency generally indicates performance, primarily as most high-efficiency panels use higher-grade N-type silicon cells with an improved temperature coefficient and lower power degradation over time. More efficient panels using N-type cells benefit from a lower rate of light-induced degradation (LID), which is as low as 0.25% of power loss per year. When calculated over the panel's 25- to 30-year life, many high-efficiency panels are still guaranteed to generate 90% or more of the original rated capacity, depending on the manufacturer’s warranty details. Due to the higher purity composition, N-type cells offer higher performance by having a greater tolerance to impurities and lower defects, increasing overall efficiency.
Efficiency does make a big difference in the amount of roof area required. Higher efficiency panels generate more energy per square meter and thus require less area. This is perfect for rooftops with limited space and allows larger capacity systems to be fitted to any roof. For example, 12 x higher efficiency 440W solar panels, with a 22.5% conversion efficiency, will provide around W (1.2kW) more total solar capacity than the same number of similar size 300W panels with a lower 17.5% efficiency.
12 x 300W panels at 17.5% efficiency = 3,600 W
12 x 440W panels at 22.5% efficiency = 5,280 W
In real-world use, solar panel operating efficiency depends on many external factors. Depending on the local environmental conditions, these various factors can reduce panel efficiency and overall system performance. The main factors which affect solar panel efficiency are listed below:
Solar Irradiance (W/m2)
Shading
Panel orientation
Temperature
Location (latitude)
Time of year
Dust and dirt
The factors which have the most significant impact on panel efficiency in real-world use are irradiance, shading, orientation and temperature.
The level of solar irradiance, also called solar radiation, is measured in watts per square meter (W/m2) and is influenced by atmospheric conditions such as clouds & smog, latitude and time of year. The average solar irradiance just outside the Earth's atmosphere is around W/m2, while the solar irradiance at ground level, averaged throughout the year, is roughly W/m2, hence why this is the official figure used under standard test conditions (STC) to determine the solar panel efficiency and power ratings. However, solar irradiance can be as high as W/m2 in some locations during the middle of summer when the sun is directly overhead. In contrast, solar irradiance can fall well below 500W/m2 on a sunny day in winter or in smoggy conditions.
Naturally, if the panels are fully shaded, the power output will be very low. However, partial shading can also have a big impact, not only on panel efficiency but on reliability and total system efficiency. For example, partial shading on a single panel in a string can reduce power output by 50% or more, significantly reducing the power of the entire string. This is because panels are connected in series, and shading one panel affects the whole string. More importantly, permanent or fixed shading over a small area can cause the bypass diodes to fail, leading to more severe problems. Therefore, it is essential to attempt to reduce or eliminate shading whenever possible. Luckily, there are add-on devices known as optimisers and microinverters, which can reduce the negative effect of shading, especially when only a small number of panels are shaded. Using shorter strings in parallel can also help reduce the impact of shading, as the shaded panels in one string will not affect the current output of the parallel, unshaded strings.
The power rating of a solar panel, measured in Watts (W), is calculated under Standard Test Conditions (STC) at a cell temperature of 25°C and an irradiance level of W/m2. However, in real-world use, internal cell temperature generally rises well above 25°C, depending on the ambient air temperature, wind speed, time of day and amount of solar irradiance (W/m2).
During sunny weather, the internal cell temperature is typically 20-30°C higher than the ambient air temperature, which equates to approximately 8-15% reduction in total power output, depending on the type of solar cell and its temperature coefficient.
Most manufacturers also specify the power rating under NOCT conditions, or the Nominal Operating Cell Temperature, to provide an average real-world estimate of solar panel performance. NOCT performance is typically specified at a cell temperature of 45°C and a lower solar irradiance level of 800W/m2, which attempts to approximate a solar panel's average real-world operating conditions.
Conversely, extremely cold temperatures can increase power generation above the nameplate rating as the PV cell voltage increases at lower temperatures below STC (25°C). Solar panels can exceed their rated power (Pmax) for short periods during very cold weather. This often occurs when full sunlight breaks through after a period of cloudy weather.
Cell temperatures above or below STC will either reduce or increase the power output by a specific amount for every degree above or below 25°C. This is known as the power temperature coefficient, which is measured in %/°C. Monocrystalline panels have an average temperature coefficient of -0.38% /°C, while polycrystalline panels are slightly higher at -0.40% /°C. Monocrystalline N-type IBC cells have a much better (lower) temperature coefficient of around -0.30%/°C, while the best-performing cells at high temperatures are HJT (heterojunction) cells, which are as low as -0.25% /°C.
The power temperature coefficient is measured in % per °C - Lower is more efficient.
Polycrystalline P-Type cells - 0.39 to 0.43 % /°C
Monocrystalline P-Type cells - 0.35 to 0.40 % /°C
Monocrystalline N-type TOPcon - 0.29 to 0.32 % /°C
Monocrystalline N-Type IBC cells - 0.26 to 0.30 % /°C
Monocrystalline N-Type HJT cells - 0.25 to 0.27 % /°C
The chart below highlights the difference in power loss between panels using different PV cell types. N-type heterojunction (HJT), TOPcon and IBC cells show far lower power loss at elevated temperatures compared to traditional poly and monocrystalline P-type cells.
A standard size 60-cell (1m x 1.65m) panel with 18-20% efficiency typically has a power rating of 300-330 Watts, whereas a panel using higher efficiency cells, of the same size, can produce up to 370W. As previously explained, the most efficient standard-size panels use high-performance N-type IBC or Interdigitated Back Contact cells which can achieve up to 22.8% panel efficiency and generate an impressive 390 to 440 Watts.
Popular half-cut or split cell modules have double the number of cells with roughly the same panel size. A panel with 60 cells in a half-cell format is doubled to 120 cells, and 72 cells in a half-cell format have 144 cells. The half-cut cell configuration is slightly more efficient as the panel voltage is the same, but the current is split between the two halves. Due to the lower current, half-cut panels have lower resistive losses, resulting in increased efficiency and a lower temperature co-efficient, which also helps boost operating efficiency.
To decrease manufacturing costs, gain efficiency and increase power, solar panel manufacturers have moved away from the standard 156mm (6”) square cell wafer size in favour of larger wafer sizes. There are a variety of cell sizes now available, with the most popular being 166mm, 182mm and 210mm. The larger cells, combined with new larger panel formats, have enabled manufacturers to develop extremely powerful solar panels with ratings up to and above 700W. Larger cell sizes have a greater surface area and, when combined with the latest cell technologies such as multi-busbar (MBB), TOPcon and tiling ribbon, can boost panel efficiency well above 24%.
Visit our community discussion about the best solar panels in our solar forum
For more 36 cell solar panelinformation, please contact us. We will provide professional answers.
Previous: Unlock Savings and Sustainability: Transform Your Future with a Solar Energy System
Next: A guide to purchasing energy storage for businesses - INTILION
If you are interested in sending in a Guest Blogger Submission,welcome to write for us!
All Comments ( 0 )