What Are the Most Efficient Solar Panels?

Solar for Homeowners | 4 min read
What Are the Most Efficient Solar Panels?

If you’re looking for the best solar panels, efficiency can be a good metric to consider. In this blog, we’ll explain what exactly solar panel efficiency means, and we’ll also share the brands with the top ten most efficient solar panels.

What Does Solar Panel Efficiency Mean?

The efficiency of a solar panel is the percentage of the sun’s energy the panel converts to electricity.

For example, let’s say the sun shines the equivalent of 1 kilowatt (kW) or 1,000 watts on your solar panel. Your solar panel converts that energy into 200 watts of electricity that you can use to power your home or business. This panel would have an efficiency of 20%.

Most solar panels today are between 17% to 19% efficient. The least efficient panels will be around 15% efficient, and the highest are just shy of 23% efficiency.

The more efficient your solar panels, the more electricity your system will produce. In some cases, installing panels with higher efficiency means you can install fewer panels and still meet your electricity needs. This can be helpful with space concerns. However, it’s often the case that the more efficient the solar panel the more expensive they are as well. Typically, a higher quantity of less efficient panels will be cheaper than a smaller quantity of high efficient panels, even if the total system size is the same.

Why Aren’t Solar Panels 100% Efficient?

The most efficient solar panel comes in at 22.8%. That number can seem underwhelming. But the sun gives off such an immense amount of energy that even capturing a fraction of it can generate enough electricity to power many homes, businesses, and farms.

The efficiency of a solar panel is limited by the type of energy the sun produces. This energy falls across a large spectrum. Just like only a small fraction of this energy is visible to humans, present-day technology allows for only a portion of it to be converted into electricity with solar panels. Research and development teams at solar panel manufacturers are continuously working to harness a larger percentage of energy on that spectrum, which leads to increased efficiency of their panels.

If solar panels continue to get more efficient, you may wonder whether you’d be better off waiting until technology advances a bit more. But most people won’t be better off, as the small incremental gains in panel efficiency won’t make up for the months or years of free energy you’re missing out on.

The Ten Most Efficient Solar Panels 

Here are the brands that offer the ten most efficient solar panels.

Manufacturer Solar Panel Model/Series Efficiency
SunPower X Series 22.8%
REC Alpha Series 21.7%
Jinko Solar Tiger Pro 21.4%
Canadian Solar Series 7 21.4%
Trina Solar Vertex 21.1%
LONGi Solar Hi-MO4m 20.7%
Panasonic 340N HIT 20.3%
Q Cells Q.PEAK DUO 20.2%
Solaria PowerXT 20.2%

While efficiency can certainly be a valuable metric when selecting the solar panels for your system, it shouldn’t be the only thing you take a look at. A high-efficiency percentage isn’t the only indicator of a high-quality panel.

You should look at the duration of the product and performance warranties offered by the manufacturer. You should also take into account what size (60-cell vs. 72-cell) and what type (monocrystalline vs polycrystalline) of solar panel best suits your installation budget, available space, and aesthetic style.

In addition to installing the high-efficiency Q-Cell panels, we’re proud to install Axitec panels, which come in with efficiency ratings at 17.9% .

While not high enough to crack the top ten list, this brand creates high-quality, well-warrantied panels in a variety of sizes and types. Depending on the specifics of your system, you may be better off installing panels from this brands, even if that means a few additional panels.

What Factors Cause Variations in Panel Efficiency?

The solar panel efficiency rating you’ll see advertised on the manufacturer’s website or the solar panel’s spec sheet won’t always be the real efficiency level of your panels once they’re installed.

The number advertised by the manufacturer is the panel’s efficiency under standard testing conditions. These are lab-controlled conditions that stay constant across the industry to account for any possible variables. Ratings and measurements that are taken under standard testing conditions make it easy to compare products, but these conditions aren’t always replicated out in the real world.

Here are a few factors that could cause your solar panels to produce less electricity than what’s predicted by the spec sheet.


Irradiance is how much energy an area receives from the sun. The greater this number, the more electricity your solar panels will produce. Variations in irradiance reaching your solar system can occur due to the tilt of the panels, the seasonal variations in the sun’s location in the sky, and weather patterns.

The optimum tilt will vary depending on where you’re located. If you install a system at a higher latitude, you’ll be better off installing your solar system at a higher degree tilt. If you’re closer to the equator, you’ll have a more efficient system the flatter it is. As a rough rule of thumb, the degree tilt of your solar system should about match your latitude.


The sun’s rays hit the Earth differently as seasons change. The northern hemisphere gets the most direct sunlight during the summer, and the least during the winter, due to the Earth’s tilt on its axis. The more direct the sunlight, the more electricity your solar system will produce. During the summer months, your output will be higher than during the winter when the sun sits lower in the sky and the days are shorter.

Weather can also impact irradiance. Clouds, be them white and fluffy or dark and stormy, can stop sunlight from reaching your solar panels. This will impact how much electricity your solar panels generate.


You might think summer is the time of year your panels are most efficient. However, when it’s cooler out, your solar system produces more voltage and more electricity. As temperature rises, your panels will generate less voltage and will become less efficient. For each degree below standard testing condition, your panel will become about ½ percent more efficient.

Dust, Dirt, and Shading

Clean this solar panelAnything that blocks sunlight will hinder your solar panels’ production. A thick build up of dust and dirt, especially if you live in a dusty area prone to droughts, can cause enough blockage to negatively impact your solar system’s production. Depending on how thick this layer of dirt is, and how often your area gets rain showers, you may be better off cleaning your panels.

In addition to dust and dirt, shade from nearby trees, buildings, exhaust fans, or even mountains or hills can reduce your solar system’s production by blocking sunlight from reaching your panels.

Getting the Best Solar Panels on the Market

The more efficient a solar panel is, the more electricity your system is capable of producing. That’s an attractive prospect when choosing which solar panels to install. You want to optimize the energy you produce with the space that you have.

However, efficient solar panels are also more expensive, and efficiency shouldn’t be the only factor you consider when choosing a panel. Wattage size is a very important factor when trying to optimize panel production. Additionally, the price, quality, warranty, and panel type are all things you need to take into account as well.

Your solar installer will be able to help you determine which brand and type of solar panel will be best for achieving your production and financial goals.

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