SunPower solar panels review

SunPower Solar Panels: The Complete Review

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SunPower solar panels are one of the most frequently requested solar panel brands on the EnergySage Solar Marketplace, and for good reason. Their panels are some of the most efficient products on the market today, and they offer an industry-leading warranty. EnergySage’s SunPower reviews take a look at the technical specifications of SunPower solar panels as compared to other manufacturers to answer the question, once and for all, of whether SunPower is actually the best solar panel brand on the market.

How SunPower X-Series, E-Series, and A-Series solar panels compare to other panel manufacturers

As you evaluate overall solar panel quality, there are four key metrics that you should consider: efficiency, performance, warranties, and price. To help you with your decision, EnergySage has developed SunPower reviews for each metric, along with a comparison of SunPower solar panels (including the esteemed SunPower X-Series) against the other leading panel manufacturers offered on the EnergySage Marketplace.

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Find out what solar costs in your area in 2020


The term “solar panel efficiency” refers to how well a solar panel can convert sunshine into useful electricity. Given the same conditions, a high-efficiency solar panel can produce more electricity than a lower-efficiency panel of the same size. For this reason, a higher efficiency rating is generally preferable.

SunPower solar panels are the most efficient panels currently available on the market in the United States. While the majority of solar panels fall in the 14% to 18% efficiency range, SunPower’s products are much more efficient – between 16.5% and 22.8%. If efficiency is your top priority, the technical specifications of SunPower solar panels are unparalleled.

Performance (temperature coefficient): SunPower X-Series

For this portion of EnergySage’s SunPower reviews, we use the temperature coefficient as an indicator of panel performance. The temperature coefficient represents how well your solar panel can handle less-than-ideal conditions. Solar panels, like other electronics, perform their best when they are kept cool (ideally around 25° C/77° F). You can use the temperature coefficient to get a sense of how your panel’s performance will change during hot sunny summer days.

For every degree above 25° C (77° F), your solar panel’s electricity production will decrease by its temperature coefficient. For example, SunPower’s SPR-X21-345 panel has a temperature coefficient of -0.3%/°C. This means that, if the panel’s temperature increases by one degree from 25° C (77° F) to 26° C (79° F), its electricity production will be reduced by -0.3%. If its temperature increases all the way to 35° C (95° F), electricity production will decrease by 3%.

Ideally, you want the lowest temperature coefficient possible. SunPower’s solar panels offer some of the best temperature coefficient ratings on the market today, between -0.38 and -0.29.


Whether you’re buying a TV, a car, or solar panels, the manufacturer should stand behind their product with a strong warranty. A solar panel’s materials warranty (sometimes referred to as the product or equipment warranty) guarantees that it will be replaced in the event of equipment failure due to manufacturing defects or environmental issues.

Most solar panel manufacturers offer a 10-year materials warranty, but the best solar panels come with a 12, 15, or even 25-year warranty. In keeping with SunPower’s industry-leading position in the other metrics we’ve assessed, the company offers a 25-year warranty against any defects in their products.

Every solar panel’s production naturally degrades over time. The performance warranty is a manufacturer’s guarantee that your solar panels’ production won’t degrade too quickly. In addition to a leading materials warranty, SunPower offers one of the best performance warranties of any solar panel manufacturer we’ve reviewed. Most solar panel brands offer a performance warranty stating that their panels will still be producing at somewhere between 80% and 83% of their original capacity after 25 years. By comparison, SunPower’s performance warranty is 92% after 25 years – a full 9% to 12% higher than most other panel manufacturers offer.

How much do SunPower solar panels cost?

Our SunPower reviews wouldn’t be complete without a discussion of how much SunPower solar panels cost. As you might expect, if you want to invest in the highest-quality solar panels available, you’ll end up paying a higher sticker price as a result.

However, the price of SunPower solar panels might not be as high as you think. We reviewed quotes offered on the EnergySage Solar Marketplace that included SunPower solar panels and found that these systems were priced between $2.83/Watt and $3.83/Watt. By comparison, the average price on the Marketplace during the same time period was $2.96/W – SunPower systems were pricier, but not by an astronomical amount.

This means that, for an average 6 kW system, your gross cost would be anywhere from $16,980 to $22,980. However, remember that most homeowners end up paying much less than the total gross cost. There are plenty of solar incentives and rebates to help you reduce upfront costs, including the 26 percent federal tax credit for solar.

How to find the best price on SunPower solar panels 

SunPower panels are, without a doubt, some of the best solar panels available today. When EnergySage ranked the best solar panels on the market, our SunPower reviews were the highest of any panel brand.

If you have a limited amount of space and need to maximize your solar panel system’s production, you can’t go wrong with an installation that includes SunPower solar panels. However, not every homeowner needs the most efficient panels available on the market. If you have enough space for a larger system, installing slightly less efficient panels may give you the performance you need at a slightly better price.

The best way to determine whether SunPower solar panels are the best solar panels for your home is to review multiple quotes with different solar equipment options before making a decision. When you compare all of your options on the EnergySage Solar Marketplace, you’ll find the right combination of price and quality that meets your needs. When registering, simply note in your profile that you’re interested in receiving quotes that include SunPower solar panels for your home. Many of our qualified, pre-vetted solar installers are part of SunPower’s certified solar installer network, which means you can be confident that every aspect of your solar system installation meets the highest standards.

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Find out what solar costs in your area in 2020

NOTE: the data in this piece was last updated January 2020 and is updated every 6 months.

28 thoughts on “SunPower Solar Panels: The Complete Review

  1. Jon

    After many quotes and discussions, just signed up with the Sunpower master dealer here in my neck of the Las Vegas metro area. My 11kw system has X21-335w panels paired with the Enphase micro inverters, as well as an electrical panel upgrade. Gross cost installed is $3.18/watt, net after tax rebate is $2.22/watt. This was very nearly the cheapest quote I got per installed wattage – one cheaper spec’d with chinese panels and solaredge – but on a rate of return perspective this was the cost winner given the much higher efficiency. So very cost competitive. Of course, that means they need to actually work which remains to be seen. Expecting install in early 4th quarter.

  2. Matt

    After getting multiple quotes, with rebates and incentives, going through the local master Sunpower dealer in CT was the most cost effective. They offered the most production and with an equivalent or lower price than the other quotes. Currently in the process of having the system installed and looking forward to the results.

  3. Erol

    Hi Jon,

    Curious to know, for your 11KW system, what Is the estimated production in LV?

    Your numbers seem great, for reference, I purchased a 9.45MW system in Westchester County, (summer 2018, so 1 yr prior), at a gross cost of $3.50/watt. Estimated annual production is ~11,300kwhr’s. Grid electricity costs in our county avg. $0.21/kwhr, so paying an extra 10-20% for our system (I assume your production efficiency must be much better given your location) is more than offset by us having some of the most expensive electricity rates on continental US.

    Just interesting that cheaper prices for installed panels available where you are, as I significantly negotiated down our contract from $4.1/watt initially. Feels like manufacturers know they can charge higher prices in Northeast where comparative electricity rates essentially protect their pricing power.

  4. Don Briggs

    I own SunPower panels. I am REALLY disappointed in their monitoring system. The one they make available to consumers is rudimentary. It’s suitable for children. In addition, they lost the ability to monitor my system on 11/26/19. I discovered this loss of communications on 12/3/19. Their “monitoring” system says, “We lost communication with your system but it’s probably working.” Well, it was not, in fact, working. And I’m married to these guys for 25 years.

  5. Jeff

    Too bad Sunpower does not honor their warranty. Too bad Sunpower takes years to respond to requests to repair or replace their failed system.

    Bold statements about a great warranty, until you actually need to use the warranty.

    I paid top dollar or as Sunpower says “slightly more” for a system that failed and Sunpower failed to make it right.

    Oh and the production guarantee? You guessed it, not provided as per agreement.

    Simply put, Sunpower is NOT a reputable product.

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