SunPower solar panels review: Efficient, effective & expensive

Image credit: SunPower

Before SunPower declined into bankruptcy, the former industry icon was known for its superior solar cell technology and hefty price tag. 

SunPower had four decades of experience before the company filed for bankruptcy in August 2024. Its solar panels appealed to those looking to install a highly efficient solar panel system to integrate with other products, like a solar battery. From solar panels to hardware, SunPower most recently sold complete solar energy systems for residential and commercial applications. At the heart of its operations was its cell technology, the most efficient on the market.

Complete Solar purchased some of SunPower’s assets, but the future of its operations is still unclear. The good news is that you can still take advantage of SunPower’s legendary solar cell technology through its former manufacturer turned independent business, Maxeon Solar Technologies.

SunPower’s cell technology earned the company its reputation as the most efficient on the market. Although it stopped manufacturing its own products in 2020, SunPower designed three lines of residential solar panels: SunPower Maxeon (M-Series), SunPower Performance (P-Series), and the U-Series. 

Maxeon Solar Technologies, SunPower’s former manufacturing arm, produced the Maxeon and Performance panels, but as of 2024, you can purchase Maxeon solar panels from other installers. A few different companies, including Waaree, manufactured the more budget-friendly U-Series panels.

SunPower solar panels

For solar panels, the most important specs to watch are:

• Efficiency: How well a solar panel captures sunlight and converts it into electricity for your home, expressed as a percentage (i.e., 22.2%). The higher, the better. 

• Temperature coefficient: How well your solar panels perform in less-than-ideal conditions, expressed as a percentage per degree (i.e., 0.34% / °C). The lower, the better. 

• Warranty: Guarantees that the company will replace your panel if it fails due to manufacturing defects or environmental issues. Warranties also guarantee a certain amount of production throughout the 25+ year term.

SunPower vs. other popular brands

*Price reflects the average price per watt based on more than 10,000 real-world quotes on the EnergySage Marketplace. It is not specific to the model listed.

Top-notch solar panel technology

Maxeon's technology, which SunPower used for some of its panels, is the best of the best. The monocrystalline, half-cut cell structure reduces heat loss because the cells are smaller, making them more efficient than conventional panels. The Maxeon-produced solar panels enhance efficiency even more through interdigitated back contact (IBC) and shingled solar cell technology.

• IBC cells have electrical contacts on the back rather than on the front like conventional solar cells. This eliminates any metal grid-like lines on the front of the panel, allowing for the entire front of the cell to absorb sunlight. The back of the panel is held together with a layer of durable copper to prevent corrosion and other common causes of failure. 

• Shingled solar cells are regular cells cut into strips and arranged like shingles on a roof. Instead of using metal ribbons to connect the cells, shingled solar cells use an electrically conductive adhesive (ECA), boosting flexibility and durability. 

The U-Series panel used 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.

Backed by a standout warranty (or so we thought)

SunPower solar panels came with one of the longest and most comprehensive warranties on the market. The 25-year Complete Confidence warranty covered not just panels but inverters and racking equipment, too. The warranty guaranteed panel production of at least 85%–92% of their original output by the end of the term.

Unfortunately, SunPower’s warranty coverage post-bankruptcy is uncertain. It’s likely that customers will lose at least some coverage; the company stated it had an independent reserve of $100 million for exactly this scenario, but it’s still unclear how customers will be supported by SunPower.

Fortunately, Maxeon announced its support for SunPower customers. The manufacturer will provide product warranty coverage on solar panels made by Maxeon (this doesn’t include support for other system components like inverters).  

Good for those with space constraints

More efficient panels mean you can install fewer panels on your roof for a sleeker look.  If you had a smaller roof or just wanted to minimize the number of panels for aesthetic reasons, SunPower was a good option.

You can find comparable panels at a lower cost

As we mentioned, Maxeon now sells to other residential installers—and they have a cheaper price per watt than SunPower had on the EnergySage Marketplace. 

Maxeon solar panels are the most efficient on the market, but more affordable brands like REC Group and QCELLS aren’t too far behind. Looking at the table above, REC Group actually outranks SunPower. The REC panel beats SunPower on temperature coefficient and is the cheapest option of the three. Depending on your goals and circumstances, the efficiency perk may not have been enough to justify the price.

SunPower’s shifting dynamics

SunPower’s decline wasn’t totally shocking. Looking back, the writing was on the wall. 

SunPower officially split from Maxeon in 2020 but maintained an exclusive partnership until March 2024. Under that agreement, SunPower branded and installed all Maxeon and Performance solar panels. Unfortunately for SunPower, those supply agreements were terminated, meaning Maxeon was free to sell its high-efficiency solar panels elsewhere.

A month after SunPower lost its exclusivity with Maxeon, the company announced it was leaving residential direct sales and other key business decisions made to boost financial viability. Breached credit agreements, massive layoffs, and other financial woes plagued the company in the months leading up to its filing, which very well could have put off prospective customers.

There’s no denying SunPower’s status as an industry pioneer. But SunPower bestowed its technology to Maxeon years before it went bankrupt. If performance is your priority, ask your installer about Maxeon’s products. Just remember that while they may be slightly cheaper than SunPower systems were, Maxeon is still a premium brand. 

Ultimately, the best way to determine whether Maxeon solar panels are the best solution for your home is to review multiple quotes with different solar equipment before deciding.