Solar panel efficiency: how much it matters, top brands & more

Updated

5 most efficient solar panels lined up vertically left to right
The five most efficient residential solar panels in 2022.

If you’re shopping around for solar panels, you’ve probably come across the term ‘solar panel efficiency’. It’s on practically every solar manufacturer's website in bold font: “19% Efficiency!”, or “Our highest efficiency solar panel!”

But what does solar panel efficiency even mean? Is it the most important thing to look for in a solar panel? And what impacts how efficiently a solar panel operates in the real world? 

Key takeaways

  • Solar panel efficiency is a measure of how much sunlight that hits the surface of a solar panel is converted into electricity that can be used.
  • Most solar panels used today have efficiencies between 15% and 20%.
  • Sunpower, LG Solar, and REC Group manufacture the most efficient solar panels on the residential market today.
  • The type of solar panel, the construction of the panel, and outdoor conditions all impact how efficiently a solar panel operates.
  • The power output rating and the value of the solar panel you choose is more important than the efficiency rating.

What you need to know about solar panel efficiency:

    What is solar panel efficiency?

    The efficiency rating of a solar panel tells you what amount of sunlight that hits a solar panel is turned into usable electricity. The higher the efficiency rating, the more sunlight that panel can turn into electricity. 

    So, if a solar panel has a 15% efficiency rating, that means 15% of the solar energy within the sunlight that hits the solar panel will be converted into electricity.

    You can get a more in-depth explanation of solar panel efficiency from SolarReviews founder Andy Sendy in this video: 

    How efficient are solar panels? 

    According to the National Renewable Energy Laboratory (NREL), most solar panels installed today have efficiency ratings between 16% and 22%, with an average efficiency rating of 19.2%. 

    Solar panels with efficiency ratings over 20% are considered premium efficiency panels, and tend to come with a higher price tag. Some well-known premium efficiency panel brands include Sunpower, LG Solar, and REC Group.

    While 20% doesn't seem like that high of a number, we’ve actually come a long way when it comes to the efficiency of solar panels. When silicon solar panels were first invented in 1954, one solar panel was only 6% efficient. Just 10 years ago, the average solar panel had an efficiency of 13.4%. Now, we’re at 19.2%! And with exciting new advancements like perovskite solar cells, we may even reach efficiency ratings of 50%!

    10 most efficient solar panels of 2022

    The following table outlines the 10 most efficient residential solar panels of 2022: 

    Table 1. Most efficient solar panels in 2022
    # Manufacturer Model Power
    Output
    Efficiency*
    1 SunPower M Series 440 W 22.80%
    2 SunPower A Series** 420 W 22.50%
    3 LG Solar NeON R ACE 405 W 22.30%
    4 REC Group Alpha Pure 410 W 22.20%
    5 Panasonic EverVolt 380 W 21.70%
    6 Silfab Solar Elite 380 W 21.40%
    7 Risen Energy Titan 410 W 21.30%
    8 Q Cells Q. Peak Duo Black ML 370 W 20.60%
    9 Solaria PowerXT 370 W 20.50%
    10 Jinko Solar Eagle G4 390 W 20.43%

    *Some commercial solar panels have efficiency ratings higher than those listed; this list is meant to represent high-efficiency residential solar panels. 

    **Other Sunpower A-series models, such as the 400 W, 410 W, and 415 W models, have higher efficiencies than other models listed, however, we wanted to show a wider variety of the premium efficiency panels on the market.

    How much do high efficiency solar panels cost?

    You can expect to spend somewhere between $27,000 and $30,000 for an 8 kilowatt solar system that uses premium efficiency solar panels, before incentives. In comparison, the same sized solar energy system using standard efficiency panels would cost between $20,000 and $26,000, before incentives

    Find out how much a solar system would cost for your specific home

    There’s no denying it: high efficiency panels are going to cost you more money to install than standard efficiency panels. However, there are more and more solar panel manufacturers, specifically Chinese manufacturers, coming out with panels that have efficiencies above 20% at much more competitive prices.

    Brands like Trina Solar and LONGi now offer great-quality panels with efficiency ratings above 20%, but offer them at much lower prices than companies like Sunpower. They still cost a bit more than a standard efficiency panel, but if this trend continues, prices for high efficiency Chinese solar panels could get just as low as the price for standard panels. 

    What factors impact solar panel efficiency ratings?

    Solar panels are manufactured kind of like a layer cake - there's the front glass sheet, a layer of encapsulant, the solar cells, more encapsulant, a backsheet, and an aluminium frame holding it all together.

    The materials used to make these layers (mostly the solar cells and the backing) play a major role in how efficiently a solar panel can turn sunlight into electricity, and they include:

    • Cell type
    • Busbars and wiring
    • Backing

    Let’s take a closer look at each, and how they impact the efficiency of a solar panel. 

    Solar cell type 

    One of the biggest determinants of solar panel efficiency is the type of solar cell used. Solar cells are the part of the solar panel that takes the sunlight and turns it into electricity. There are three main types of silicon solar cells: polycrystalline, thin-film, and monocrystalline. 

    You only really need to know about monocrystalline panels - they’re used for almost every solar installation, and every single high-efficiency solar panel on the market today uses some form of monocrystalline solar cell technology. Some of the most common high efficiency monocrystalline silicon cell types include:

    • PERC solar cells: Also called ‘passivated emitter and rear contact cells’, PERC cells typically provide about 1% in added efficiency thanks to a reflective back layer that reflects any light that may have passed through the cell back into it.
    • HJT solar cells: Heterojunction with intrinsic thin layer cells are just traditional monocrystalline solar cells that have been sandwiched between layers of a different type of silicon that absorbs various wavelengths of light and increases power production. Panasonic and REC Group are known for using HJT solar technology.
    • Half-cut or Split cells: Split-cell technology is exactly what it sounds like - solar cells are cut in half with a high precision laser, which reduces heat and resistance, thereby increasing overall efficiency. 

    Busbars and wiring 

    The way that solar cells are wired together can also impact how efficiently they can generate electricity. If you look at the face of a solar panel, you’ll see a bunch of thin lines. These are a series of copper or aluminum wires that conduct electricity, moving it from the solar cell to the solar inverter

    Some solar manufacturers have switched to multi-busbar technology, where multiple ultra-thin busbars are used, as opposed to fewer, thicker busbars. The thinner busbars reduce the amount of shading on the solar cell and allow it to absorb more sunlight, thus increasing efficiency.

    Sunpower uses Interdigitated back contact, or IBC cells, where all busbars and wiring are on the backside of the solar cell. This frees up the entire face of the cell to absorb electricity without shading issues. However, IBC cells are complicated and expensive to manufacture. 

    Backing 

    If you’ve ever looked at a traditional solar panel, you’ve probably seen the black solar cells surrounded by some white space. That white space is the panel’s backsheet. You may also have seen some solar panels that are all-black; these panels might have a black backsheet. 

    Black backing is popular among homeowners because it gives the panels a really sleek, uniform look by blending seamlessly with the color of the solar cells. However, panels with black backing are slightly less efficient than those with white backing, because it makes the solar panels hotter. The hotter a solar panel, the less electricity it can produce

    Do environmental conditions affect a solar panel’s efficiency?

    Everything we’ve talked about so far is specifically talking about a solar panel’s efficiency rating. The efficiency rating is calculated under a standard set of laboratory testing conditions, and unfortunately, solar panels on your roof won’t be getting these ideal settings. 

    This means how efficiently your panel will actually be will vary, depending on many factors, including: 

    • Temperature: As the surface of a solar panel gets hotter, its efficiency drops. Solar panels actually operate best in cold, but sunny conditions. You can learn more details about how temperature affects solar panels here.
    • Solar system orientation: In the U.S., solar panels produce electricity most efficiently on roofs facing south. Solar panels that face other directions will get less sunlight, which decreases how efficiently the panel operates. You can read more about how roof direction impacts solar panels here.
    • Solar system angle: Ideally, solar panels should be installed at an angle between 30° and 45°, depending on where you live. If your roof has a very steep or shallow pitch, it might decrease the amount of electricity solar panels can produce. You can learn more about this here.
    • Shading: If a solar panel experiences any shading, like the shadow from a tree branch, it won’t produce as much electricity. Depending on the inverter you have, shading on one panel could actually impact the production of multiple panels. We have a complete guide on how shading impacts solar panels.
    • Weather: Solar panels operate best on clear, sunny days. Even a passing cloud can impact how much electricity the panels generate. Snow accumulation can prevent energy production altogether, so you might need to clear them off if you get a lot of snow.
    • Debris: If you live somewhere that is particularly dusty, or maybe in a place that experiences regular wildfires, debris may accumulate on your solar panels and reduce the amount of sunlight they can turn into electricity. Even something as small as bird poop can cause a drop in solar production. Most often, rain storms will take care of removing anything on your panels, but you may need to consider cleaning them off to maximize electricity production. 
    Find out if going solar is worth it based on your location

    How is solar panel efficiency calculated?

    When you’re shopping for solar panels, the efficiency rating will be listed on the panel’s datasheet. But how exactly is it calculated? There’s actually a pretty easy formula for calculating solar panel efficiency: 

    Efficiency = [Power output of panel / (Area of panel x solar irradiance)] x 100

    When solar panels are tested in the lab under Standard Test Conditions (STC), it’s assumed they will receive irradiance levels of 1,000 watts of sunlight per square meter. Knowing this, let’s calculate the efficiency rating for a: 

    350-watt panel with an area of 1.8 square meters: 

    Efficiency rating = [350 watts / (1.8 m2 x 1,000 watts per m2)] x 100

    Efficiency rating = 19.4%

    So, this 350-watt panel has an efficiency rating of 19.4%. Not bad!

    Do you really need high efficiency solar panels?

    We’re going to be totally honest with you, the efficiency rating of a panel is not the most important thing to look at

    You can learn more about this from veteran solar expert Will White: 

    What you really want to focus on is the power rating of the panel. The power rating tells you how much electricity a solar panel is able to produce. It gives you a better overall picture of what the solar panel can do, while also taking the efficiency of the panel into account. 

    So, for instance, let’s say you’re choosing between two panels: Panel A has an efficiency rating of 19%, Panel B has an efficiency rating of 17%, and both panels have a power rating of 350 watts. It doesn’t really matter that Panel A has a higher efficiency rating than Panel B because they both have the same maximum energy output of 350 watts. Instead of just picking the panel with the highest efficiency, you should also consider how much the panel costs, and if the cost is worth the value the panel will provide. 

    Typically, the only scenario where high efficiency solar panels are worth it is if you have limited roof space and need each and every solar panel to produce as much power as possible. 

    Learn more: How many solar panels do I need to run my house?

    The following table lists some of the solar panels we recommend instead of expensive premium efficiency panels: 

    Manufacturer Model series Output Efficiency
    LG Solar NeON 2 335 W 19.60%
    Q Cells Q. Peak Duo Black 350 W 19.50%
    JA Solar MBB Half-Cell 370 W 19.90%
    Trina Solar Residential Half-Cut Mono PERC 365 W 19.80%
    Jinko Solar Eagle 66-TR G4 380 W 19.91%
    REC Group REC N-Peak 2 360 W 19.70%
    Canadian Solar HiKu Mono PERC 360 W 19.50%
    Solaria Power-XT 360 W 19.90%
    Axitec Solar USA AXIpremium XL HC BLK 360 W 19.76%
    Seraphim S3 Series 360 W 19.76%

    Are premium efficiency solar panels right for you?

    As we said before, premium efficiency panels probably aren’t necessary for most homeowners. They tend to be more expensive than standard efficiency panels without giving you a ton of added benefit. 

    So if you have limited roof space or your roof isn’t an ideal orientation for solar, you might want to consider a high efficiency panel, as they could boost your electricity production a bit. Or if money isn’t a concern for you and you just want the highest tech solar panel system you can get, then be our guest - go for those premium efficiency panels! 

    But for everyone else, you should consider what solar modules give you the best value for the price. You want a solar panel that’s reliable, good quality, and meets your energy needs, without breaking the bank. LONGi, LG Solar, and Q. CELLS offer a variety of solar panels, including premium efficiency ones, that are sure to power your home without costing you an arm and a leg, and they are among the list of the Top 10 Best-Selling Solar Panels in 2022.

    To get a better idea of how much solar panels can save you, check out our solar panel calculator. From there, you can get in contact with local, reliable solar installers who can help you pick the best solar panel brand for your roof so you can start powering your home with cheap, clean energy. 

    Find out how much you will save annually by switching to solar
     - Author of Solar Reviews

    Catherine Lane

    SolarReviews Blog Author

    Catherine is a researcher and content specialist at SolarReviews. She has strong interests in issues related to climate and sustainability which led her to pursue a degree in environmental science at Ramapo College of New Jersey.

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