Solar panel efficiency: how much it matters, top brands & more
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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?
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:
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%!
The following table outlines the 10 most efficient residential solar panels of 2022:
|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%|
|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%|
|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.
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.
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.
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:
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 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:
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.
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.
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, 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:
|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%|
|Axitec Solar USA||AXIpremium XL HC BLK||360 W||19.76%|
|Seraphim||S3 Series||360 W||19.76%|
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.