Complete review of SunPower solar panels: Are they really the best?


sleek black monocrystalline SunPower solar panels on a roof
SunPower offers high-quality panels, but are they worth the equally high price? Image source: Kamtech Solar

SunPower is one of the hottest names in solar. The California-based company, founded in 1985, was originally intended to develop concentrated solar systems but has since become one of the most well-known residential solar panel manufacturers. 

In 2019, SunPower announced that it would no longer manufacture solar panels. Instead, newly formed company Maxeon Solar would focus on manufacturing SunPower’s high-efficiency solar panels, while SunPower continues to focus on designing and monitoring solar systems. 

There is no denying that SunPower’s high-quality panels have awesome technical specifications and a top-notch warranty. But are they worth the premium price? Let's find out.  

Key takeaways

  • SunPower is a premium solar solutions company with its own line of high-end residential and commercial solar panels manufactured by Maxeon Solar.
  • There are four residential solar panel lines offered by SunPower: the M Series, the A Series, the X Series, and the E Series.
  • SunPower residential panels have some of the highest efficiency and power ratings on the market.
  • You can expect to pay a minimum of $3.30 per watt for a SunPower solar system, which comes out to about $19,800 before incentives for the average 6 kW system.
  • SunPower comes at a premium price but offers excellent module quality and performance, as well as a top-notch warranty, and a reliable dealer network.

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

    What products does SunPower offer?

    SunPower has four lines of residential solar panels: 

    • M Series
    • A Series
    • X Series
    • E Series

    In addition to their residential solar panels, SunPower sells commercial versions of their Series A, X, and E panels. The company also has its P Series panels designed for large-scale commercial installations. 

    Each of these product lines varies in terms of its performance and appearance, making them better suited for certain applications. Let’s take a closer look.

    SunPower M Series solar panel 

    sunpower m series solar panel

    The Sunpower M Series is an ultra-powerful AC solar panel with power ratings up to 440 W and a record-breaking efficiency rating of 22.8%. Image source: SunPower

    Table 1. SunPower M Series solar panel specs
    Wattage 420 W - 440 W
    Efficiency rating 21.7% - 22.8%
    Power tolerance -0/+5%
    Cell type Monocrystalline Maxeon Gen 6
    Product warranty 25 years
    Performance warranty 25 years; 98% power capacity after Year 1; no more than 0.25% annual degradation until Year 25

    SunPower’s newest and most powerful solar panels come from their M Series product line. M Series panels are AC solar panels with built-in microinverters and are designed to work with the SunPower Equinox system - a solar system that consists entirely of SunPower-branded products. 

    The SunPower M Series modules use Maxeon’s newest solar cell, the Maxeon Gen 6. The Gen 6 cell is even bigger than the cells used in the company’s record-breaking A Series panels, allowing the M Series to become the most efficient and powerful residential solar panel available on the market

    These panels are best suited for homes with limited roofing space for solar installations. Because the M Series panels are incredibly high-powered, offering between 420 and 440 Watts, you can install fewer panels and still produce a lot of electricity. However, choosing these panels does limit you to only using SunPower products, and will likely be way more expensive than many other panels on the market today.

    SunPower A Series solar panel 

    SunPower A Series solar panel 

    The SunPower A Series AC solar panel's specs are some of the most impressive on the market. Image source: Stellar Solar

    Table 2. SunPower A Series solar panel specs
    Wattage 390 W - 420 W
    Efficiency rating 20.9% - 22.5%
    Power tolerance -0/+5%
    Cell type Monocrystalline Maxeon Gen 5
    Product warranty 25 years
    Performance warranty 25 years; 98% power capacity after Year 1; no more than 0.25% annual degradation until Year 25

    The A Series is one of SunPower’s most popular and most impressive product lines. With power ratings ranging from 370 to 420 watts, A Series panels are some of the most powerful solar panels homeowners can put on their roofs today. 

    You can thank the Maxeon Gen 5 solar cell for its outstanding performance. These solar cells are about 65% larger than the solar cells used in the X and E Series panels, allowing more sunlight to be converted into electricity. However, the Gen 5 cells are about 5% smaller than the Gen 6 cells used in the M Series. 

    The A Series can be purchased as traditional DC solar panels with either white or black backing, or as AC solar panels with an integrated microinverter. Just like the M Series, the AC version of the A series is designed specifically to pair with the SunPower Equinox system.

    The A Series is best for homes with a limited amount of roofing space that is suitable for solar installations, as you can install fewer panels and still meet your energy needs. Keep in mind though, the A Series comes at a higher price tag than other panels on the market (more on that below).

    SunPower X Series solar panel 

    sunpower x series solar panel

    The SunPower X Series AC solar panel. Image source: KamTech Solar

    Table 3. SunPower X Series solar panel specs
    Wattage 327 W - 370 W
    Efficiency rating 20.4% - 22.7%
    Power tolerance -0/+5%
    Cell type Monocrystalline Maxeon Gen III
    Product warranty 25 years
    Performance warranty 25 years; 98% power capacity after Year 1; no more than 0.25% annual degradation until Year 25

    The SunPower X Series panels use smaller SunPower Maxeon Gen III solar cells, making their power ratings slightly lower than the A Series, but still suitable to meet most homeowners’ needs. Plus, the X Series does come with very high-efficiency ratings. 

    Similar to the A Series, X Series panels can be purchased with either white or black backing, and as either DC or AC solar panels. These are the first solar panels to have been awarded the Cradle to Cradle Bronze Award, which recognizes the X Series as a sustainably manufactured product. 

    The X Series is another panel that works well for homeowners with limited roof space because of its high-efficiency ratings. 

    SunPower E Series solar panel 

    SunPower E Series solar panel SunPower E Series panel. Image source: SunPower

    Table 4. SunPower E Series solar panel specs
    Wattage 320 W - 327 W
    Efficiency rating 19.4% - 20.4%
    Power tolerance -0/+5%
    Cell type Monocrystalline Maxeon Gen II
    Product warranty 25 years
    Performance warranty 25 years; 98% power capacity after Year 1; no more than 0.25% annual degradation until Year 25

    The E Series doesn’t have all the flashy specs of other SunPower solar panels, but that doesn’t mean it’s not a great product. You can think of the E Series as the company’s most “standard” panel, with power ratings between 320 W and 327 W and efficiency ratings on the higher end of average. Sunpower offers the E Series in both DC and AC models. 

    The E Series is a solid solar panel that will be able to meet the energy needs of practically every homeowner.

    Note: Maxeon solar technology is currently exclusive to SunPower, so you need to use a SunPower dealer to get these panels. Starting in 2023, you’ll be able to find panels that use Maxeon solar cells from installers outside of SunPower’s network.

    How much do SunPower solar panels cost?

    SunPower panels are high quality, but that also means they come at a high price. You can expect to pay a minimum of $3.30 per watt of SunPower solar panels installed with a cash purchase (cash purchases of solar systems tend to be cheaper per watt than financed systems because they don’t include things like broker fees). 

    $3.30 per watt is more expensive than the $3.00 per-watt average most homeowners in the U.S. spend on conventional panels. And again, that’s the lowest price you can expect. Going with one of their premium models, like the 420 W Series M, could run up an even higher price tag.

    The total price for a SunPower solar system will vary based on a few factors, like your location, which panels you choose, and the system size. The following table outlines how much you can expect to pay for different-sized SunPower solar systems before incentives are considered

    Table 5. SunPower solar system costs by size
    System size Cost before incentives
    4 kW $12,520
    6 kW $19,800
    8 kW $26,400
    10 kW $33,000
    12 kW $39,600

    It’s also important to note that the price of a SunPower quote will be even higher if you finance the system, whether it be a lease, loan, or PPA. Some customers have reported price quotes as high as $6.50 per watt when financing was included.

    How do SunPower solar panels compare to other solar panels?

    Check out SolarReviews CEO Andy Sendy’s expert review of SunPower solar panels below:  


    Power output rating 

    The power output rating (also called the wattage) of a solar panel is a measure of how much electricity the solar panel can produce. 

    SunPower’s M Series 440 W panel has the highest power output rating of any residential solar panel on the market today. With such a high power rating, you can install fewer solar panels to cover your electric bill. 

    Aside from the M and A Series, both the X and E series offer decent power ratings. No matter which SunPower panel you pick, the power rating will not be a problem. 

    Efficiency rating 

    The efficiency rating of a solar panel represents what percentage of sunlight hitting the panel actually gets turned into electricity. Just like with power ratings, SunPower has some of the highest efficiency ratings on the market. 

    Don’t get us wrong, having a high-efficiency rating is great, but you shouldn’t put too much weight into it. Any reputable solar panel brand you choose will likely have efficiency ratings above 18%, and most homes don’t need any more than that. 

    Solar panel efficiency only really matters if you have limited roofing space, but many solar panel brands like to use high-efficiency ratings as a way to level up on their competition. Plus, having premium efficiency ratings like SunPower’s can add quite a bit to how much you’ll end up paying. So, you have to decide if having the most efficient solar panels on the market is worth the extra money.

    Power tolerance 

    Power tolerance is another key specification to look at when buying solar panels, but it’s often overlooked. See, solar panels have their rated power output, but how much electricity they produce can actually fluctuate - even if the conditions don’t change. 

    That’s where power tolerance comes in. The power tolerance tells you how much the power output of a panel can actually change, even when the conditions remain the same. 

    Most solar panels have a power tolerance rating between -0/+3% and -0/+5%. What exactly does that mean? The -0 means that the panel will always operate at least at its rated capacity under Standard Test Conditions (STC). The +5% means that it could produce up to 5% more power under STC. 

    SunPower’s panels all have a power tolerance rating of -0/+5%, which is right in line with industry standards. 

    Cell type 

    The main difference between each of SunPower’s solar panel series is they all use different solar cells. They are all monocrystalline solar cells that are manufactured by Maxeon, however, the M Series uses the newest and largest solar cell, the Maxeon Gen 6, which is what allows the M series to be so powerful.

    The A Series uses Maxeon Gen 5 solar cells, which are slightly smaller than the Gen 6 cells, but still produce a ton of electricity - and do it quite efficiently. Despite being a bit behind the M Series in terms of power output and efficiency, SunPower’s A Series are still some of the most powerful residential panels available today.

    The X Series uses the Maxeon Gen III solar cells, which are still highly efficient, but their size limits the amount of power they can produce. And finally, the E Series uses the Maxeon Gen II solar cells, so they’re just a little bit older and don’t use all the same brand new technology the Gen III and Gen 5 cells use.

    Is SunPower’s warranty all it’s cracked up to be?

    SunPower really does offer an excellent product warranty and an excellent performance warranty that can serve to give homeowners peace of mind.

    Product warranty 

    Let’s start with the product warranty. SunPower solar panels have a 25-year product warranty, meaning that their panels will be free from material and workmanship defects, so long as they are operated as intended and installed correctly. 

    Most solar panel manufacturers only offer a 12-year product warranty, or they make you complete an extra registration step to unlock the 25-year warranty. 

    Performance warranty 

    Then there’s the performance warranty. Solar panels degrade as they get older, so the performance warranty gives you an idea of how your solar panels will operate as they age. 

    In the first year, SunPower’s solar panels will operate at no less than 98% of their original rated capacity. For the next 24 years, the panels will degrade no more than 0.25% each year. 

    This annual degradation rate is half of the 0.5% degradation rates most solar panels in the industry offer (the lower, the better). So, SunPower panels produce more power over time than other solar panels because they degrade more slowly. This is one of the best warranties we’ve seen

    If you choose to install the SunPower Equinox complete system, your entire system from the panels to the racking system will be covered by the SunPower Complete Confidence Warranty

    Should you get SunPower solar panels for your home?

    There's a reason SunPower panels have an Elite ranking in SolarReview's official solar panel review - you can't go wrong with getting SunPower solar panels on your roof. SunPower has an excellent network of over 500 reputable solar installers, many of which are among the best installation companies in the country. This means you're getting high-quality panels with an excellent warranty and a high-quality installation.

    But, all those great things come at a premium price. If budget is a concern, you may want to consider some of our other top-ranked solar panel brands like Qcells or LONGi Solar, which give you great quality at a slightly lower price point.

    Whether it's SunPower panels or panels from another manufacturer, most homeowners will save money on their electricity bills when they install solar. Use our solar panel calculator to get an idea of the savings you can get when you switch to solar and see if solar panels are the right investment for you.

    Find out how much you can save monthly by installing solar on your home
     - 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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