As the solar industry has expanded, the number of solar panel brands available in the market has increased substantially. There are now several different solar panel brands available to the consumer, both through solar installers and online.

However, at the premium end of the solar market there are just three brands that dominate: SunPower, LG Solar (or just LG for short), and Panasonic. 

Homeowners often have trouble deciding between them. How can you tell which of the three offers the best quality and performance? Luckily, there are three main criteria you can use to objectively compare different solar panels, namely: 

  • Warranty
  • Efficiency
  • Temperature coefficient (performance in the heat)
  • Cost

Now, let’s look at how each of the three premium solar panel manufacturers stack up. We’ll be comparing each brand’s current flagship residential solar module: SunPower’s A-Series, LG’s NeON 2, and Panasonic’s HIT®+ Series. 

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Warranties of SunPower, LG, and Panasonic compared

There are two types of solar panel warranties: a product warranty and a power output warranty. 

The product warranty covers the product if it fails as a result of a manufacturing flaw or poor-quality components. 

The power output warranty is a guarantee that the panel will produce a certain percentage of its rated power after a certain number of years.

Product warranty compared

SunPower, LG, and Panasonic all offer the same product warranty on their solar panels: 25 years. This is much better than the industry standard of 10 years. 

This long product warranty coverage, combined with the fact that solar panel failure is very rare, means that all three brands offer buyers peace of mind. 

Power output warranty compared

All three premium brands maintain their power output much better than average solar panels. 

However, SunPower has a slight edge: they currently guarantee the lowest degradation (loss of output) of all solar panels in the market. That means that with each passing year, SunPower solar panels will give you slightly more power output compared to the other two brands.  

Power output warranty of Sunpower, LG, and Panasonic
Brand Degradation rate* Output Year 1 Output Year 10 Output Year 25
SunPower 0.25% 98% 95.75% 92.00%
LG 0.30% 98% 94.30% 90.80%
Panasonic 0.26% 97% 94.66% 90.76%

*Annual power output degradation rate Years 2-24

Panel efficiency of SunPower, LG, and Panasonic compared

The efficiency of a solar panel is the percentage of light hitting the panel that is converted into energy. A solar panel with a higher efficiency will require less space to reach a desired output.

The industry standard for solar panel efficiency is about 17%. SunPower, LG, and Panasonic all beat that by a fair margin as their high-efficiency panels use the best solar cell technologies. 

Efficiency of LG, SunPower, and Panasonic panels
Brand Highest panel efficiency
SunPower 22.8%
LG 21.7%
Panasonic 20.3%

SunPower in particular has made a name for itself as the market leader in efficiency. Their most efficient solar panel model, the A-Series, is also the world’s most efficient residential solar panel as of September 2020. 

Temperature coefficient (heat performance) of SunPower, LG, and Panasonic compared

The temperature coefficient is the percentage decrease in power output for every degree Celsius the panel reaches beyond 25°C/77°F. 

Like most electronics, solar panels produce less energy the warmer they become. And dark solar panels absorb a lot of heat, so their temperature tends to be a lot higher than the surrounding air temperature.

This makes temperature coefficient a great indicator as to which panels will hold up best in real-world conditions.

Temperature coefficient of SunPower, LG, and Panasonic panels
Brand Temperature Coefficient
SunPower -0.29% / Celsius
LG -0.30% / Celsius
Panasonic -0.258% / Celsius

Panasonic has the lowest temperature coefficient, and is thus the best solar panel by this metric. Their panels’ power output will only decrease by 0.258% for every degree Celsius over 25°C/77°F. 

Prices of SunPower, LG, and Panasonic compared

Solar panel costs are usually measured by cost per watt. You can use this figure to find out the total price of a solar panel system by multiplying it by the total system size (i.e. 6 kW, or 6000 watts).

To compare the prices of the three premium brands, we calculated each brand’s average installation price based on their top-selling solar panel models in 2020.

Average cost of SunPower, LG, and Panasonic panels (Sept 2020)
Brand Avg. cost per watt Avg. 6 kW system*
SunPower $2.92 $17,520
LG $2.82 $16,920
Panasonic $2.88 $17,280

*Cost before applying solar incentives 

The cheapest of the three brands, LG Solar, costs $0.10 per watt less than the most expensive, which is SunPower. 

The difference in cost may not appear significant, but it adds up when applied to a full solar power system: an average 6 kW system using LG Solar panels will be $600 cheaper than an average 6 kW system that uses SunPower panels.

Which premium solar panel is best overall?

There’s no single panel that’s perfect for every solar system. Each brand offers a slightly different warranty, efficiency, temperature coefficient, and cost. 

Comparing key specs for SunPower, LG, and Panasonic
Brand Product warranty Warrantied Year 25 output Panel efficiency Temp. coefficient Avg. cost per watt
SunPower 25 years 92.00% 22.8% -0.29% / Celsius $2.92
LG 25 years 90.80% 21.7% -0.30% / Celsius $2.82
Panasonic 25 years 90.76% 20.3% -0.258% / Celsius $2.99

If roof space is tight and money isn’t an issue, perhaps opting for the slightly higher efficiency SunPower A-Series or SunPower X-Series is best.

If you live somewhere where temperatures consistently stay very high, Panasonic modules are worth considering due to their superior temperature coefficient (heat tolerance). 

LG solar panels, meanwhile, remain popular for being a well-known electronics brand that offers good value among the premium brands. 

All said, there really are no bad choices out of SunPower, LG, or Panasonic. Each of these high-quality brands will perform excellently installed on your roof, and they’re all backed by a 25-year warranty. 

Furthermore, solar incentives are available regardless of which solar panel brand you choose: in 2020, every homeowner can claim 26% of their system cost as a deduction to their federal taxes under the federal solar tax credit. 

For a free estimate of how much going solar will cost you with local incentives included, try out our solar calculator below.

See what it would cost to install premium solar panels on your home

Key takeaways 

  • SunPower, LG, and Panasonic all offer high-quality solar panels with industry-leading product warranties.
  • SunPower has the most efficient solar panels available, which means they take up the least space on your rooftop.
  • SunPower also has the best power output warranty — their panels see the least drop in performance over time.
  • Panasonic has the lowest temperature coefficient, so they perform the best in high temperatures.
  • All three brands have similar costs, but LG Solar is the cheapest of the three.
  • When it comes to performance and reliability, you can’t go wrong with any of these brands, really.