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 and E-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.


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 19.1% and 22.2%. If efficiency is your top priority, the technical specifications of SunPower solar panels are unparalleled.

SunPower solar panels efficiency

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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. As you can see in the graph below, SunPower’s solar panels offer some of the best temperature coefficient ratings on the market today, ranging from -0.38 to -0.3.

SunPower solar panels performance graph


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 an 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.

SunPower solar panel warranties

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.

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How much do SunPower X-series 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 $3.65/Watt and $4.55/Watt. By comparison, the median price on the Marketplace during the same time period was $3.50/W – SunPower systems were pricier, but not by an astronomical amount.

SunPower solar panels compared to competitors

MeasureSunPower Panels25th Percentile50th Percentile75th Percentile
Efficiency (%)19.1% - 22.2%15.7%16.2%16.8%
Temperature Coefficient-0.3 - -0.38-0.45-0.43-0.41
Warranty (Years)25101225
Price ($/Watt)$3.65 - $4.55$3.25$3.50$3.75

This means that, for an average 5 kW system, your gross cost would be anywhere from $18,250 to $22,750. 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 30 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. All SunPower solar panels received at least a “Premium” rating, and it was the only brand with panels that received a “Premium +” rating.

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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Other EnergySage solar equipment resources

15 thoughts on “SunPower Solar Panels: The Complete Review

  1. Tim

    Zac is exactly right, Sunpower is/was the manufacture of their micro inverters but have now acquired Enphase for future micro inverters. It is without question that Sunpower makes the best panels, so why they don’t use the best and latest technology (SolarEdge) to even squeeze more efficiency out of there panels is a huge question. The new Trump Tariff exemption will allow Sunpower totally DOMINATE the industry. I just got a quote on a complete Sunpower 360 watt X-panel system at $3.10 watt and $2.70 watt from two different installers. That shows how affordable Sunpower has become.

  2. Brad

    According to the article, $3.65-4.55/W is price range for SunPower panels based on recent. Tim mentions $3.10 and $2.70/W. Is this explained by regional price differences, or are there installers that offer narrower profit margin pricing? Are these installers reputable?

  3. Andrew

    This comment is directed toward Brad. In no way shape or form can I see someone getting quoted $2.70 for an X-series module. Not happening.

    One of two things occurred;

    1. Tim might have put the NET PER WATT PRICE versus the GROSS PER WATT PRICE. I’d love for him to provide the information or phone number to this installer before they go bankrupt with their pricing structure.
    2. *Me wearing my tin foil hat* Tim is a shill for a non-sunpower company and throws out these ridiculously low quotes as a form to reverse psychologically have people believe there price is great. That is until they actually get quoted by an authorized Sunpower provider, have the potential solar buyer completely not go with sunpower because their pricing is too high or because they feel the energy representative is price gouging them. Which then in turn leads the buyer to another solar provider.

    Maybe Tim is just anti-sunpower, who knows.

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