A solar panel's efficiency rating tells you how much of the sunlight that hits the panel is turned into usable electricity. The higher the efficiency rating, the more sunlight that panel can turn into electricity.
Solar panel efficiency has been increasing for decades. Today, most home solar panels have efficiency ratings between 19% and 21%. The most efficient home solar panel on the market today is SunPower’s M-series panel, which has an efficiency rating of 22.8%!
How efficient a solar panel is is impacted by the type of solar panel, how it’s constructed, and the outdoor conditions where it’s installed. Let’s take a closer look at the most efficient panels for homeowners today, how much they cost, and what other factors impact 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:
The median efficiency rating of residential solar panels installed from 2022 to 2021.
According to the National Renewable Energy Laboratory (NREL), most solar panels installed today have efficiency ratings between 19% and 21%. Solar panels with efficiency ratings close to the 22% mark are considered premium efficiency panels and are only offered by a few manufacturers like SunPower and REC Group.
That’s a long way from where we were in 1954 when the first silicon solar panels had efficiency ratings of just 6%. Just ten years ago, solar panels were only about 13.4% efficient! We could see even more improvements in efficiency thanks to exciting new advancements like perovskite solar cells, which have the potential to reach efficiency ratings of 50%!
The following table outlines the most efficient residential solar panels of 2023:
# | Manufacturer | Model | Power Output |
Efficiency* |
---|---|---|---|---|
1 | SunPower | M Series | 440 W | 22.80% |
2 | SunPower | X-Series | 370 W | 22.70% |
3 | Canadian Solar | HiHero | 440 W | 22.50% |
4 | REC Group | Alpha Pure | 410 W | 22.20% |
5 | Panasonic | EverVolt H | 410 W | 22.20% |
6 | Maxeon | Maxeon 3 | 420 W | 22.2% |
7 | Silfab | Elite | 410 W | 21.4% |
8 | LONGi | HiMO4M | 460 W | 21.20% |
SunPower has consistently held the number one spot when it comes to efficient ratings, but that could change in the near future. In 2020, SunPower’s manufacturing branch, Maxeon, spun off as its own company. SunPower’s most efficient panels are still manufactured by Maxeon. But in 2023, Maxeon solar panels are becoming available to installers outside SunPower’s network. The break-up could finally dethrone SunPower as the most efficient panel, but they’re still holding strong for now.
You could spend a few thousand dollars extra for premium efficiency solar panels.
High-efficiency solar panels tend to come with a higher price tag and can add a premium of over $2,000 to the total cost of your system. So, a 7 kilowatt (kW) solar system using premium efficiency panels might cost around $23,100, while the same system using regular efficiency panels might be closer to $19,900.
But, the cost of highly efficient solar panels is getting lower, thanks to brands like Trina Solar and LONGi. These Chinese-based companies are making great-quality panels with excellent efficiency ratings for a fraction of the cost of premium brands like SunPower. As these brands develop more products, you could see efficiencies rise while solar panel costs remain the same.
Solar panels are manufactured like a layer cake. There's the front glass sheet, a layer of encapsulant, the solar cells, more encapsulant, a backsheet, and an aluminum frame holding it all together.
The materials used to make these layers play a major role in how efficiently a solar panel can turn sunlight into electricity. They include:
Let’s take a closer look at each and how they impact the efficiency of a solar panel.
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 turns sunlight into electricity. There are three main types of silicon solar cells:
Monocrystalline solar panels are the most common type of solar panel used today because they perform better than other cell types. This hasn’t always been the case, though. Believe it or not, polycrystalline panels were once the most popular because they were substantially cheaper than the alternatives.
But, monocrystalline technology continued to improve while getting cheaper, making it the best choice for residential solar installations. The shift to monocrystalline panels is a big reason why average efficiency ratings have increased over the years.
As we said, most solar panels today use monocrystalline solar cells. But, there are different ways in which monocrystalline solar cells can be constructed to make them even more efficient. These include:
How 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 throughout the panel.
Some solar manufacturers have switched to multi-busbar technology, where multiple ultra-thin busbars are used instead of 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 and Silfab use 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.
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 all-black solar panels; these panels might have a black backsheet.
Black backing is popular among homeowners because it gives the panels a 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. Believe it or not, as the surface of a solar panel gets hotter, its efficiency decreases.
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:
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!
We’re going to be totally honest with you; a panel's efficiency rating is not the most important thing to consider. In fact, our top pick for the best solar panel manufacturer of 2023 doesn’t have the highest efficiency panels on the market.
You can learn more about this from veteran solar expert Will White:
What you should focus on is the power rating of the panel and the reliability of the brand you’re using. The powering rating tells you how much electricity a solar panel can produce, which considers the panel's efficiency.
You also want to consider the brand’s reliability. You want to get solar panels from a company that produces high-quality products that can support you over the 25-year lifespan of the panels, should you need it.
However, you should get solar panels with a higher efficiency rating if you have limited roofing space. If you have a small roof, or only a small portion is suitable for a solar installation, get panels with a higher wattage which are likely to have a higher efficiency rating. It may be more expensive, but it’ll be the best way to get the amount of solar that you need on your roof to cover your electric bill.
Learn more: How many solar panels do I need to run my house?
The following table lists some alternatives to expensive high-efficiency solar panels:
Manufacturer | Model series | Output | Efficiency |
---|---|---|---|
Qcells | Q.Peak DUO Black MK | 410 W | 20.90% |
Jinko Solar | Eagle 66-TR G4 | 400 W | 20.96% |
Trina Solar | Vertex S 395 W | 395 W | 20.80% |
Mission Solar | MSE PERC 66 | 400 W | 19.9% |
JA Solar | 60-Cell MBB Half-Cell Module | 390 W | 21% |
Premium efficiency solar panels are the best choice for homeowners with limited roofing space or those who don’t mind spending extra money on top-of-the-line products.
Solar panel efficiency really isn’t that important. Solar panel manufacturers love to use efficiency ratings as a way to boost their brands’ legitimacy, but it’s mostly just marketing.
In reality, solar panel efficiency doesn’t matter as much as other performance metrics in most cases. Not only that - when a solar panel has higher efficiency, it allows the brand to justify a higher price tag, and in turn, causes homeowners to shell out more money than they need to (without giving substantial added benefits).
You should consider what solar modules give you the best value for the price. Can you trust the manufacturer? Is the warranty good? You want a solar panel that’s reliable, high-quality, and meets your power needs without breaking the bank. Qcells, LONGi, and Canadian Solar are all great options.
Also, take a look at power tolerance and temperature coefficient ratings. Both of these specs give you insight into how the panel will perform under real-world conditions. Look for power tolerance ratings around -0/+5% and temperature coefficient ratings between -0.3% and -0.5% per degree Celsius.
To better understand how much solar panels can save you, check out our solar panel calculator. From there, you can contact 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.