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Detailed reviews and information of the best solar panels, inverters and batteries. Plus hybrid and off-grid solar system reviews and information articles on how solar and battery systems work.

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Reviews and information on the best Solar panels, inverters and batteries from SMA, Fronius, SunPower, SolaX, Q Cells, Trina, Jinko, Selectronic, Tesla Powerwall, ABB. Plus hybrid inverters, battery sizing, Lithium-ion and lead-acid batteries, off-grid and on-grid power systems.

SunPower Solar Panels Review

Jason Svarc

SunPower solar panel Review.jpg

home > solar panels > best solar panels review > Sunpower Review

Company background

SunPower Corporation has a long rich history in solar manufacturing and many consider them to be the solar industry technology leader. This is a very big claim but it’s hard to disagree as they currently produce the most efficient residential solar panel with the lowest degradation and best performance warranty on the market. Although like most things, high performance comes at a high price.

SunPower started in a lab in the early 80’s and officially became SunPower in 1988. After securing funding from investors the R & D team developed record breaking PV cells using advanced cell technology (which were used by the NASA space program) along with Honda to win the world solar challenge car race in Australia. These achievements put SunPower on the world stage as one of the leading solar cell manufacturers, plus laid the foundation for the high-efficiency Maxeon IBC cells used today.

Update - SunPower Splits into two companies

Nov 2019 - In a surprise announcement SunPower revealed it will be separating into two independent public companies - SunPower and Maxeon Solar, with each company focusing on a different market segment.

  • SunPower will focus purely on the North American Solar market with distribution, sales and installation of solar panels, energy storage and associated products.

  • Maxeon Solar or ‘Maxeon Solar Technologies’ will become the global developer, distributor and manufacturer of the range of Maxeon cells and Solar panels.


SunPower cells used on the SolarStratos solar powered aircraft - Image credit SunPower Corp

SunPower cells used on the SolarStratos solar powered aircraft - Image credit SunPower Corp

During the 2000s, SunPower expanded and built advanced facilities in the US, Mexico, Europe and Asia to manufacture high-efficiency solar panels. Over the last decade, the only other manufacturer able to compete at the same level of efficiency and performance was LG Energy with the Neon R range of panels which use a similar IBC cell technology.

However, it hasn’t all been smooth sailing for SunPower. Over recent years the company ran into serious financial issues and racked up a considerable level of debt due to high overhead costs and pressure from the extremely competitive Chinese and Korean panel manufacturers. The financial troubles forced SunPower to restructure its business and manufacturing operations and now the financial situation is looking more positive. See detailed company analysis in this article from PV-Tech.


SunPower Panel and Cell Technology

Maxeon IBC cells

SunPower began mass production of the high-performance IBC (Interdigitated Back Contact) cells back in 2007 and have led the industry ever since using what is considered the most efficient cell technology available today. Unlike the common monocrystalline and polycrystalline solar cells which use front mounted busbars and fingers to collect current, IBC cells have a fine grid of conductors integrated into the rear side of the cell. The IBC cell design which SunPower refers to as ‘Maxeon’ uses a grid of N-type and P-type silicon on the rear side which increases efficiency by eliminating the need for front exposed busbars that partially shade the cell. The SunPower IBC cells are built on a base of high purity N-type silicon which also increases performance and has a low degradation rate which is how SunPower can offer the leading performance warranty of 92% retained capacity after 25 years on both the E series and X series as well as the new generation Maxeon 2 and Maxeon 3 series.

SunPower Maxeon IBC cells used on the X series panels - Image credit Sunpower Corp

The current generation (3 & 4) IBC cells from SunPower are the smaller format 5” (125mm x 125mm) size configured in a 96-cell layout with 8 rows of 12 cells. Almost all other manufacturers have moved to the 6” (156mm x 156mm) cell size which makes up a common 60 cell panel. Cell size doesn’t affect performance but more cells do equate to a higher voltage which can be problematic for domestic installations which can have a voltage limit of 600V (depending on the country). A higher voltage means fewer panels can be linked together in a string before the upper voltage limit is reached.

For details on Enphase IQ7 and SunPower Maxeon compatibility and other solar questions, check out our solar power forum.

Maxeon 2 and Maxeon 3 - New 104 cell format

The latest generation panels from SunPower simply named the Maxeon 2 and Maxeon 3 use even more cells, in a new 104 cell format with 8 rows of 13 gen-3 cells, to create the worlds most powerful residential solar panel at 400Wp. The full series Maxeon 3 panels ranges from 370 to 400W and will replace the X Series while the Maxeon 2 panels ranging from 340W to 360W will replace the E series.


Shingled Cells

Shingled cell solar panel diagarm.jpg

Shingled cells are an emerging technology which use overlapping thin cell strips assembled horizontally or vertically across the panel. The SunPower P series panels described in more detail below, use the vertical format with 6 long cell strips in parallel. This offer several benefits including inproved shade tolerance when partially shaded as each long cell works independently. The thin shingled cells are also more flexible and less prone to micro-cracking which is a common issue with conventional full size square cells. These are made by laser cutting a normal full size cell in to 5 or 6 strips and layering them in a shingle configuration using rear side connection adhesive. The slight overlap of each cell strip hides a single busbar which interconnects the cell strips. This unique design covers more of the panel surface area as it doesn’t require front side busbar connections which partially shade the cell, thus increasing the panel efficiency much like IBC cells.

SunPower P series panels use P-type shingled cells - Image credit SunPower Corp

SunPower P series Shingled cell construction - Image credit SunPower Corp

The P series uses conventional P-type silicon which is not as efficient as the high performance N-type silicon used the Maxeon, but much more cost-effective and still achieve a very respectable efficiency of 19.9%. The P series is also backed by the SunPower 25 manufacturer’s warranty.


The SunPower Range of Panels

With the addition of the Performance series SunPower now have a more diverse range of panels for residential and commercial applications. The new Maxeon panels have now replaced the previous E and X series which used the high efficiency IBC cells to compete in the premium end of the market. The more price competitive performance or P-series panels use the overlapping shingle cell design and complete more in the commercial market.

The latest generation panels from SunPower named Maxeon 2 and Maxeon 3 and will replace the long standing E and X series and will be based on the slightly larger 104 cell format.

Maxeon 3

The Maxeon 3 is the new flag ship of the SunPower range and is available in a range of sizes from 370 to 400Wp for residential installations. Based on the Gen 3 high performance IBC cell technology the new 104 cell format increases power output further and tops the range with an impressive 22.6% maximum efficiency, making it the most efficient residential solar panel in the world.

SunPower Maxeon 3 series 104 cell solar panel close up.jpg

See the full SunPower Maxeon 3 Specification sheet here

Maxeon 2

Like the Maxeon 3, the new Maxeon 2 panel is based on the Gen 3 high performance IBC cell technology and uses the same 104 cell format to increase power output further and tops the range with a 20.4% maximum efficiency. However as it is based on the slighlty lower spec IBC cells the Maxeon 2 panels have a lower power rating of 340 to 360Wp, making them also much more affordable but still some of the most powerful residential panels available.

SunPower Maxeon 2 series 104 cell solar panel close up.jpg

E & X Series panels

X Series

SunPower X series panel.jpg

The X series was previously the flag ship of the SunPower range. The model numbers represented the efficiency with the base model X20 being just over 20% efficient, the X21 with a maximum of 21.4% efficiency and finally the X22 tops the range with an impressive 22.2% maximum efficiency.

The X-series utilised a less common 96 cell format using smaller high grade ‘Maxeon’ IBC cells with the lowest rate of degradation and best 25-year performance warranty today. The SunPower Maxeon IBC cells have an outstanding warranty with a guarantee of 92% retained capacity after 25 years of use.

  • X22 series – 96 cell – 360 to 370W - Monocrystalline IBC N-type

  • X21 series – 96 cell – 340W - Monocrystalline IBC N-type

E Series

Sunpower E series solar panel.png

The E series from SunPower used the previous generation Maxeon IBC cells which are slightly less efficient but are still based on the long-lasting N-type silicon substrate and offer an extremely high-performance warranty with an impressive 88% retained power rating after 25 years.

Like the X series the E20 model name refers to the efficiency with a power rating of 327W and a panel efficiency of 20.1%, making it still one of the most efficient panels available.

  • E20 series – 96 cell – 327W - Monocrystalline IBC N-type


P Series

As described in detail earlier the Performance or P series panels use the unique shingled cell design with 6 long cells in parallel. This design offers are most more cost effective and offer additional shade tolerance when partially shaded. The thin singled PERC cells based on the common P-type silicon are also more flexible and less prone to micro-cracking which is a common issue with conventional full-size square cells. The P series are available in two sizes with the smaller residential panels rated from 310W up to 335W while the larger format commercial panels are available in 380W to 405W power ratings.

See the SunPower P series specifications data sheets below:

Despite being based on standard P-type silicon SunPower still offers an impressive 25 year performance warranty as well as a 25 year manufacturer’s warranty.

Sunpower P series panels using shinged cells - Available up to 405W power ratings

Sunpower P series panels using shinged cells - Available up to 405W power ratings


New ‘A Series’ panels

Next-Generation Technology - NGT

SunPower announced early in 2019 its latest generation A series panels using what it has termed the NGT or Next Generation Technology IBC (Interdigitated Back Contact) 'Maxeon Gen 5' cells. These new larger formats 6” cells will be fabricated on a new line at its manufacturing plant in Malaysia.

The new design will be assembled into an impressively powerful 400 to 415W panel which will be the highest rated residential panel available. However, in an unusual move the A series will incorporate a micro inverter from Enphase energy and will only be available in the US market. It is expected to be available internationally once the production volume increases and the older E series lines are upgraded to the new larger format.

  • A22 series – 66 cell – 400 to 415W - Monocrystalline IBC N-type (Gen 5)


Warranty and service

SunPower offer a leading performance warranty on the E and X series which both utilise the Maxeon IBC cells based on N-type silicon. The X series has an outstanding warranty with a guarantee of 92% retained capacity after 25 years of use.

SunPower Performance warranty compared to conventional panels - Image Credit Sunpower Corp

The exact warranty details from the SunPower warranty certificate are as follows: “The power of the PV Modules will be at least 98% of the Minimum Peak Power2 rating for the first year, and will decline by no more than 0.25% per year for the following 24 years, so the power output at the end of the final year of the 25th year warranty period will be at least 92% of the Minimum Peak Power rating (the “Guaranteed Peak Power” rating)”

See the full SunPower warranty certificate here.


Sustainability

SunPower has long been the industry leader in sustainability and is the only manufacturer we know of that uses a full closed-loop sustainability strategy. SunPower’s philosophy is to drive sustainable business practices at every stage of the product life cycle and beyond. This strategy paved the way for SunPower to become the winner of the first annual Sustainability Award from pv magazine.

Cradle to cradle certified

The SunPower Maxeon Panels are the world's first solar panels to be Cradle to Cradle CertifiedTM which makes SunPower the worlds leading manufacturer when it comes to sustainability.

SunPower Cradle to Cradle certified 2.jpg

See the full detail about the SunPower cradle to cradle certification here


Conclusion

SunPower is widely regarded as a world-leading solar panel manufacturer, and very few companies can compete at the same level of performance and quality. In terms of outright efficiency, SunPower still leads the world with the Maxeon series holding the top spot as the most efficient solar panel with the lowest degradation and best performance warranty. Although not surprisingly, the Maxeon panels are also the most expensive panel on the market, but like most things, quality comes at a price. Considering that solar is a long-term investment, the higher price also equates to better performance, improved reliability, and more energy generation over the system's life.

The financial issues faced by SunPower over recent years raised some concerns over the ability for SunPower to honor the long-term warranty commitments. Despite this, SunPower is still ranked as number one in the US and many parts of the world by installers and customers alike. In contrast, the limited availability in other markets like Asia and Australia, SunPower does not have a significant presence, and the very high price of the Maxeon series can be difficult to justify when other manufacturers can offer similar performance and quality at a lower price.

On the other hand, the new P series have been very successful in the commercial solar sector, being very cost-effective and backed by one of the best warranties available. With the financial outlook improving and the next generation A-series panels now available in the US, it looks like SunPower may continue to be an industry leader for some time to come.


Solar Questions

Visit our community discussion about the Sunpower solar panel reviews on our solar info forum.