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?

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.

SolarReviews recently named Maxeon as the third-best solar panel manufacturer of 2023, largely because of the high quality of their panels. Today, two of SunPower’s panel lines are still made by Maxeon, but the company’s newest addition, the U-Series, doesn’t use the same manufacturer.

We know that Maxeon makes great panels, and we know SunPower has a stellar warranty, but it all comes at a high price. Is going solar with SunPower worth the extra cost? Let’s break it down.

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

Why you can trust SolarReviews:

SolarReviews is the leading American website for consumer reviews and ratings of residential solar panels and solar panel installation companies. Our industry experts have over two decades of solar experience combined and maintain editorial independence for their reviews. No company can pay to alter the reviews or review scores shown on our site. Learn more about SolarReviews and how we make money.

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 three residential solar panel lines offered by SunPower: the M-Series and X-Series (made by Maxeon, and the U-Series (made by other manufacturers).
  • SunPower’s Maxeon-made 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.

On this page

    What products does SunPower offer?

    SunPower has three lines of residential solar panels: 

    • M-Series
    • X-Series
    • U-Series

    SunPower sells commercial versions of some of its panels in addition to residential models.

    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 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 345 W - 370 W
    Efficiency rating 21.2% - 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 panel uses smaller SunPower Maxeon Gen III solar cells, making its power ratings lower than the M-Series, but still suitable to meet most homeowners’ needs. Plus, the X-Series models have great efficiency ratings and can be purchased as either AC or DC 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 newest X-Series modules, the X-22s, are only available with white backsheets. However, you may be able to choose a white or black backsheet if your installer still has some older X-Series panels in stock.

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

    SunPower U-Series panels

    The newest option offered by SunPower is the U-Series panels. These are installed as part of SunPower Equinox systems, so they’re covered by the company’s Complete Confidence Warranty. This means the panels will have the same 25-year performance and product warranties as other SunPower models.

    The U-Series is SunPower’s budget-friendly option. The lower price is in part because the U-Series does not use Maxeon solar technology. SunPower doesn’t list the manufacturing company or U-Series specs on its website. From what we’ve seen, it seems the U-Series panels are manufactured by either Aptos or Waaree with SunPower’s name put on them.

    Both of these options don’t offer the out-of-this-world specs that SunPower is typically known for. But nonetheless, you can trust the panels because SunPower does. Plus, you get to take advantage of SunPower’s complete system warranty, which saves you a headache if you run into problems in the future.

    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 M-Series, 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.

    The X-Series and the suspected U-Series panels offer pretty standard power ratings. Most panels today sit between 370 W and 400 W. No matter which option you choose from SunPower, they’ll be able to produce enough power to meet your needs.

    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.

    SunPower is best known for its record-breaking efficiency numbers and holds the crown for most efficient residential solar panel thanks to the M-Series’ 22.7% efficiency rating. Efficiency rating matters most to homeowners with limited roofing space, but in general, it’s not the most important specification to look at.

    The panels you get installed by a reputable installer will have a solid efficiency rating of at least 19% which is more than enough for most households. Most companies advertise high-efficiency ratings as a way to appear to get a leg up on the competition.

    Premium efficiency ratings tend to lead to higher price tags. 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 

    SunPower’s solar panels all use monocrystalline solar cells. Historically, the company has been using high-quality solar cells manufactured by Maxeon, which has given SunPower solar panels their premium performance specifications. You can still find Maxeon solar cells in the M-Series and the X-Series panels.

    Although it isn’t explicitly listed on SunPower’s website, it seems as though the U-Series panels do not use Maxeon solar cell technology. However, they are still monocrystalline solar cells that likely don’t perform as well as the Maxeon solar cells, but are still good quality.

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

    SunPower really does offer excellent product and performance warranties 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 Canadian 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

    Written Content Manager

    Catherine is the Written Content Manager at SolarReviews. She has been researching and writing about the residential solar industry for four years. Her work has appeared in Solar Today Magazine and Solar Builder Magazine, and has been cited by publications like Forbes and Bloomberg.

    Related solar news