SunPower solar panels review: Efficient, effective & expensive

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Editor's note: SunPower isn't currently disclosing current product information due to its evolving manufacturing relationships. We will update this review with information about its current product offerings once they become available. Installers may still quote SunPower panels based on their existing inventory, and those previously manufactured products remain some of the best in the industry.

In the solar energy world, SunPower is an industry pioneer with nearly four decades of experience. From solar panels to hardware, SunPower sells complete solar energy systems for residential and commercial applications. At the heart of its operations is SunPower's cell technology, which is the most efficient on the market. SunPower’s main product line is its Equinox Home Solar System, which it supports with a standout warranty.

SunPower solar panels are some of the most frequently requested on the EnergySage Marketplace, but they come at a premium price. They’re best for those looking to install a highly efficient solar panel system that can easily integrate with other products, like a solar battery. If you’re trying to go solar on a budget, SunPower solar panels might not fit the bill. 

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Key Takeaways

  • SunPower solar panels are a good investment if you value efficiency and performance over cost. 

  • SunPower solar panels are expensive. A 10-kilowatt (kW) SunPower system can cost almost $10,000 more than the average cost of solar.  

  • With an efficiency range from 20.3% to 23% and 25-year workmanship and performance warranties, SunPower solar panels lead the industry in efficiency ratings and warranties.

  • SunPower sells solar panels as part of its complete solar energy system, the Equinox Home Solar System. The Equinox System comes with panels, inverters, and all necessary hardware and easily integrates with the SunPower SunVault solar battery system.

The total price you pay for any solar panel system will vary depending on the other equipment (such as inverters and mounts) and the characteristics of your roof. Conveniently, SunPower solar panels come with built-in microinverters and all necessary hardware through the SunPower Equinox Home Solar System. The advantage of purchasing your whole system from one company is its integration with other products, like the SunVault solar battery. 

Most SunPower panels are typically priced between $3.15 and $3.97 per watt, putting them on the high side of the panel market overall. To identify the range of prices for SunPower systems, we analyzed quotes that homeowners received from installers on the EnergySage Marketplace that included SunPower solar panels. 

Based on our price per watt range, a 10 kW SunPower system costs anywhere from $31,500 to $39,700 before the federal solar tax credit – $1,400 to $9,600 more than the average cost of solar.

Thanks to solar incentives and rebates, you will most likely pay much less: The 30% federal solar tax credit alone brings the cost range of a SunPower solar panel system down to $22,050 to $27,790.

According to Solar Power World, supply agreements between SunPower and its long-time manufacturing partner Maxeon will terminate after February 2024. As of January 2024, the M and U series are still available as part of the SunPower Equinox Home Solar System. We could not confirm current information on their 360W and 370W X Series panels previously included in this review. 

Due to their changing relationship and limited public information about the future of SunPower’s solar panel models, it’s unclear how this will affect SunPower’s offerings. Although we’re unsure about SunPower and Maxeon’s changing relationship, SunPower continues to design all its solar panel systems regardless of the manufacturer. Given the company’s long standing reputation for efficiency, we don’t think this change should impact your decision to purchase.

M Series

The SunPower M Series uses Maxeon Gen 6 solar cells, offering the highest output and most efficient panels in SunPower's lineup, albeit the most expensive. With a price per watt range from $3.55 to $3.97, the M Series has six output options: 420 Watts (W), 425W, 430W, 435W, 440W, and 445W. 

Like all of SunPower's Maxeon-produced solar panels, the M Series panels use n-type, monocrystalline, half-cut solar cells (AKA the building blocks of solar panels). N-type solar cells comprise two silicon layers and are more expensive to produce than p-type cells. The half-cut cell structure of n-type solar cells reduces heat loss because the cells are smaller, making them much more efficient than conventional panels. More efficient panels mean you can often install fewer panels on your roof for a sleeker look. 

U Series

Considered their "budget" series, the U Series costs $3.15 per watt and is SunPower's most recent addition to its panel lineup. Details on the manufacturers are unavailable on SunPower’s website, but we know that Maxeon doesn't manufacture these panels. Instead, a few different solar companies build them. 

This U Series panel uses half-cut, monocrystalline, Passivated Emitter and Rear Contact (PERC) solar cells. PERC cells include a back surface layer that reflects light back through the cell, reduces heat absorption, and reduces electron recombination, all of which lead to improved panel efficiency.

Comparing your solar panel options' efficiency, performance, warranty, and price will help determine the best solar panels for you. Like SunPower, Tesla sells complete solar panel systems designed to integrate with its solar battery. Let’s see how SunPower stacks up against Tesla based on these metrics:

SunPower vs. Tesla solar panels

(Click to sort ascending)
Sun Power M Series 425W
Tesla S Series 425W
Efficiency 22.0%19.6%
Performance−0.29% / °C-0.331% / °C
Warranty25 years, 0.25% annual degradation25 years, 0.54% annual degradation

This quick comparison should help you begin to understand which product better fits your needs; Tesla is the more affordable option, but SunPower panels are more efficient and resilient. Below, we dive deeper into what these metrics mean and why they matter. 


"Solar panel efficiency" or "conversion efficiency" refers to how well a solar panel captures sunlight and converts it into electricity for your home. In the same conditions, a high-efficiency solar panel will produce more electricity than a lower-efficiency panel of the same size. When you're choosing between panels, the ones with higher efficiency ratings are generally preferable.

SunPower has earned its reputation for efficiency. Currently, the efficiency of SunPower panels ranges from 20.3% to 23%, depending on the model. SunPower claims the top spot on the EnergySage Marketplace regarding panel efficiency, with its M Series 440W panels boasting the highest efficiency rating of any home solar panel quoted to our customers.

SunPower solar panel efficiency

Solar Panel
Efficiency Rating
SunPower M Series 445W23.0%
SunPower M Series 440W22.8%
SunPower M Series 435W22.5%
SunPower M Series 425W22.0%
SunPower M Series 420W21.7%
SunPower M Series 415W21.5%
SunPower U Series 405W20.3%

Performance (temperature coefficient)

Temperature coefficient indicates how well your solar panels perform in less-than-ideal conditions. Solar panels perform better when they're kept cool (ideally around 25°C/77°F). The temperature coefficient tells you how much your panel's performance will change during hot, sunny summer days. All SunPower solar panels besides their U Series have a temperature coefficient of -0.29%/°C.

Performance of SunPower solar panels vs. other popular brands

Solar Panel Series
Temperature Coefficient
SunPower M Series-0.29%/°C
SunPower U Series-0.365%/°C
Panasonic EverVolt H Series-0.26%/°C
Tesla S Series-0.331%/°C
Tesla H Series-0.34%/°C

Ideally, the lower the temperature coefficient, the better. For every degree above 25°C (77°F), your solar panel's electricity production will decrease by its temperature coefficient. That means that for most SunPower panels, electricity production reduces by 0.29% every time the panel's temperature increases by one degree from 25°C (77°F). 

Here’s how it actually works: the SunPower M Series 440 W solar panel has an efficiency rating of 22.8% and a temperature coefficient of -0.29%/°C. If the temperature of your solar panels increases to 95°F (35 °C), efficiency will fall to 22.1%. 

SunPower's solar panels have lower temperature coefficients as far as the industry goes, but not the lowest. For comparison, the most popular brand of solar panels on EnergySage, Q CELLS, offers panels with a temperature coefficient of -0.30, while Panasonic panels all have a temperature coefficient of -0.26.


A solar panel's product warranty guarantees that the company will replace your panel if it fails due to manufacturing defects or environmental issues.

SunPower offers a comprehensive 25-year Complete Confidence warranty that covers not just their panels but inverters and racking equipment, too. The warranty guarantees panel production of at least 92% of their original output by the end of the term (except for the U Series, which guarantees at least 85% of production by the end of the term).

SunPower solar panels come with one of the longest and most comprehensive warranties on the market. 

Power output warranty of SunPower solar panels vs. other popular brands

Solar Panel Series
Annual Degradation (%)
Power At Year 25 (%)
SunPower M Series25%92%
SunPower U Series0.55%84.8%
Q CELLS Q.TRON BLK M-G2+0.33%90.58%
Panasonic EverVolt H Series0.25%92%
Tesla S Series0.54%85%
Tesla H Series0.50%86%

Whether your primary motivation for switching to solar is sustainability or lowering your electric bills, weighing your options is essential.

Pros and cons of SunPower solar panels

Pros Of Sun Power Solar Panels
Cons Of Sun Power Solar Panels
Product warranty: SunPower solar panels come with one of the most extended and comprehensive warranties available.Cost: SunPower solar panels are some of the most expensive panels on the market, making some less expensive (if somewhat lower quality) options more enticing for those concerned about costs.
Efficiency: SunPower solar panels are the most efficient solar panels currently available on the EnergySage Marketplace.Does not manufacture its own panels: Though this isn't a direct disadvantage, SunPower no longer manufactures its panels. Little information on the U Series manufacturers and their shifting dynamic with Maxeon is available.
Battery system compatibility: You can install a completely integrated system under one company with the SunPower Equinox Home Solar + SunVault Storage Systems.

There’s no denying SunPower’s status as an industry veteran. The SunPower Equinox Home Solar System is a comprehensive, sleek, and effective option for those prioritizing performance. Moreover, SunPower systems have a robust warranty that seals the deal for many solar shoppers. Still, SunPower solar panels are expensive. If affordability is your priority, these might not be the panels for you.

The best way to determine whether SunPower solar panels are the best solar solution for your home is to review multiple quotes with different solar equipment before deciding. On the EnergySage Marketplace, you'll receive quotes from our network of qualified, vetted solar installers so you can confidently go solar.

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