What is the best brand of solar panels?

The table below includes a quick look at these two panel options and how they stack up against one another.

Of all of the panel models from the manufacturers mentioned above, there are two that stand out for providing outstanding performance and overall value. These include the Maxeon 6 panels from SunPower and the Q.PEAK DUO BLK ML-G10+ from Q Cells. These both provide above-average production and savings without compromising on overall quality.

We’ll explain why we feel these panels are the best in the solar industry for home renewable energy systems below. Each panel includes a drop-down menu with additional information.

The five solar panel companies below are the manufacturers we’ve identified as the best in the industry for home PV panels:

In this article, we’ll be discussing the top five best solar panels for homes, and we’ll explain why each is a great option for your rooftop solar system. We’ll also explain what to look for in a high-performance panel to help you pick the best one for your needs. You can also refer to our review of the top solar panel installers if you’re searching for the best provider for your home.

Most solar panel manufacturers produce photovoltaic (PV) panels for residential use, but the options aren’t all created equal. Each brand has a different efficiency level, rate of degradation, durability and more, so choosing the best option for your solar project can be quite confusing. To make matters worse, opting for the wrong brand could cut into your energy savings over time.

Panasonic partners with a large network of solar installers across the country, so you should have no problem finding a solar contractor that is certified to install its products. Many of those companies are also qualified to install Panasonic’s solar batteries and inverters/microinverters.

Overall, we expect Panasonic panels to last the average of 25 to 30 years in most cases.

The efficiency warranty is one of the best in the industry, guaranteeing only a 2% loss in year one and a degradation of 0.26% annually thereafter. That means your panels will retain 91.76% of their efficiency after 25 years.

Panasonic’s warranty coverage is slightly better than the industry average but is in line with the direct competition. It includes a 25-year product warranty and 25 years of coverage for the efficiency rating. The equipment warranty includes the cost of labor to replace any panels that experience failure.

Panasonic is also the only option on our list that has a potentially negative power rating, so the performance can vary more than most of the competition at this tier. That means production could dip, depending on the weather and sun exposure.

Panasonic panels are above-average in price, coming in at over $4.00 per watt. It’s one of the most expensive options, although we feel the value you get is worth the investment. Especially since the panels have higher production rates than most other brands, these should pay for themselves, especially if you have above-average rates of electricity consumption.

Panasonic has great snow load capabilities and an industry-leading temperature coefficient of just -0.25%, so they’re an outstanding option in areas that experience extreme cold and extreme heat. This means they’ll produce more power for your home to offset a larger portion of your monthly electric bills even as the temperature rises, so they’re a good option for boosting savings if you live in a warmer climate.

The panels also have below-average degradation rates, so those above-average efficiency ratings will continue to save you more money on your energy bills for longer. Lower degradation rates also mean your panels should keep up with your electricity demands and consumption for longer, which could mean you won’t have to think about replacing your system quite as soon as you would with other brands.

Panasonic has a maximum efficiency rating of 22.2%, which is well above the industry average and higher than most of the company’s direct competition. A higher efficiency rating means more energy production, which should translate to greater savings for you on electric bills month after month.

Panasonic panels are on the expensive side, but we feel they’re worth it due to their outstanding performance.

Panasonic panels are well-known for their outstanding efficiency rating, topping out at 22.2%. However, they’re also some of the best for solar customers in extreme climates, as they have the lowest temperature coefficient of any panel option we’ve reviewed. The high efficiency and low temperature coefficient mean they’re a great solar panel option for providing maximum power in hot climates .

REC has a certification program for installers across the country. If you get your panels installed by a certified contractor following the designation installation process, you’ll usually get a superior warranty package . However, just about any solar panel installer can carry and offer REC panels, which means the brand remains widely available throughout the country.

Additionally, some of the REC panels guarantee 92% efficiency after 25 years, which is some of the lowest efficiency losses in the industry, while others have a more aggressive decline in efficiency. This means that REC panels should deliver better performance and more savings on electric bills while they’re functioning, so this could offset the risk of higher long-term costs due to shorter warranty periods.

Warranty coverage is an important thing to consider when it comes to solar panels, as a shorter warranty could mean you’ll need to pay for solar system replacement sooner. That might drive up your long-term costs of converting to clean energy.

REC is one of the few solar manufacturers that bases its warranty coverage on the panel model you have installed. Most of the panels come with a 25-year manufacturer’s warranty for the equipment and a 25-year performance guarantee, but some only include 20-year equipment coverage.

Additionally, some of the REC panel models come with below-average equipment coverage, like the REC Twinpeak 4, which has just 20 years of protection. That could mean that you’ll have to pay for panel repairs or replacement sooner than you would with other options. It also suggests that the panels don’t go through the same rigorous testing that other brands do.

REC panels come at prices that are quite a bit above average, at $3.75 per watt compared to the average of around $3.30. You do get better efficiency ratings for the price, so we still think it’s worth it, but the brand will push up your installation costs. The panel degradation is in line with the average for the top-tier brands, but at this price point, we’d love to see lower efficiency loss rates, which would mean better performance and greater savings for you over time.

REC panels are known to be highly durable and adaptable to a wide range of climates and weather conditions. It has a below-average temperature coefficient of -0.32%, which means they lose less efficiency than the average panel per degree the temperature rises above 77 degrees (F). This means REC panels are a great option for delivering high performance in hot climates. It also has above-average wind and snow loads, so it’s a durable panel brand no matter where you live.

These high efficiency ratings mean your panels will generate more power per square foot of roof space they take up, which means they should provide lower electricity bills for you over time. The high efficiency also means they’re a good option for homeowners with small roofs who need to pack in as much power as possible into a smaller area.

REC panels get a lot of things right, including efficiency. The average panel efficiency from the company is around 20.7% for residential models, which is well above average, and the max efficiency is 22.2%, making them one of the highest-rated panels available. Only a few other companies offer panels above the 22% mark.

REC panels are some of the most popular in America, in large part because they provide efficiency ratings that are well above average—topping out at 22.3%—but also have lower prices than options from other high-efficiency solar companies like SunPower and Panasonic. We’d recommend these panels to homeowners who don’t necessarily need the most impressive efficiency ratings possible but who still want above-average power output at a slightly lower cost.

As we mentioned above, Trina lets any solar contractor install its panels without voiding the manufacturer’s warranty or the performance warranty. That not only means that any panels installed by a professional will be covered but also that this panel brand is accessible to most U.S. residents.

Trina’s warranty doesn’t require any paperwork or installer training, so you don’t have to worry about not being covered because a non-certified company installed your panels. The warranty can be transferred as well, although you will need to file transfer documents if you sell your home.

The degradation in the first year and the following 24 years of the warranty term are both below average, and the company has the lowest first-year efficiency loss we’ve seen. This means your panels are virtually guaranteed to outperform most other panel brands in the long run, which translates to greater electricity savings for you in the long run.

Trina’s warranty coverage is similar to what you’ll find from most other companies on this list. The coverage for the equipment and the labor is 25 years, so you’ll remain largely insulated from panel defects for the life of your system. Ultimately, that means less of a chance of having to pay for repairs.

Trina Solar has two product lines available for residential customers: the aptly named Residential line and the Vertex line. There are five products total between the two product lines.

Trina panels also come with a lower maximum wind load than many competitors, at just 2,400 pascal units. That means they might not be ideal for homes in areas that could experience high winds from extreme weather like hurricanes, tropical storms, tornadoes and other natural disasters. If you do install them in those areas, you could be on the hook for repairs sooner than you would if you opted for more weather-resistant panels.

Trina’s average efficiency might be above the industry average, but it is lower than several other top-tier panels, like SunPower. We still feel the value provided is excellent, but there are more efficient solar options that can provide greater energy savings over time if you’re willing to invest a little more. Opting for a higher-efficiency panel could yield more savings in the long run, so Trina may not be the most cost-effective solar panel option in the long run.

That means Trina remains widely available to customers across the country via a huge network of providers, and no matter who installs your Trina panels, you get coverage that will keep your panels totally protected.

Trina has great warranty coverage for its solar equipment , but one of the most appealing aspects about the protection is that, unlike companies like SunPower, there’s no specific training required to maintain the warranty coverage.

Trina panels start out with above-average efficiency ratings as well, topping out at 20.4% and averaging around 20%, which is far better than the average of 15%. This means that Trina panels will generate more power per square foot they take up on your roof than most brands, which, ultimately, means a better chance of offsetting or even eliminating your electric bills.

All panels lose efficiency over time, but Trina provides some of the lowest degradation rates for the money. The panels are just slightly above-average in terms of cost per watt, but they outperform just about every other panel in its price range when it comes to durability.

We recommend these panels to solar customers who want outstanding value for their money and don’t have access to Q Cells panels or want to ensure their energy savings last as long as possible.

Trina outclasses Q Cells when it comes to durability, with an industry-leading 1% efficiency loss in the first year and a superior 0.4% annual degradation after that. That means your panels will continue to generate maximum energy for many years to come, which could translate to a longer time between installing your panels and having to replace them to maintain sufficient production. This could end up saving you thousands in the long run.

In our opinion, Trina Solar is right up there with Q Cells when it comes to high-quality equipment for the money. Trina panels are a bit more expensive at an average of $3.55 per watt, and they deliver similar efficiency ratings, temperature coefficients and other performance specs. Ultimately, they should save you a decent amount of money over time, and the upfront cost isn’t outlandish.

Q Cells doesn’t have a certification program for installers like SunPower does, so any solar provider that has a relationship with the company can purchase and install its panels. You should have no issues finding an installer near you that carries Q Cells equipment, although that does mean you’ll have to be careful when screening Q Cells installers to make sure yours is reputable.

Q Cells also covers efficiency for 25 years. This is also typical, but the degradation rate is below average. The first-year dip is set at a maximum of 2%, as opposed to the industry average of 2.5%, and the subsequent-year dip is 0.45%, which is just below the average of 0.5%. Overall, the slower degradation rate means your panels will continue producing more power than most other brands over the warranty term.

However, Q Cells has a special solar cell testing process that eliminates most issues related to potential-induced degradation (PID). Since PID can cause dips in panel efficiency over time, this helps Q Cells panels maintain their peak power generation capabilities.

Q Cells provides a 25-year warranty for all of its products, which covers manufacturer defects. This is in line with what most competitors provide, and it means you’re unlikely to have to pay for panel maintenance or major repairs unless inclement weather becomes an issue.

As mentioned above, Q Cells has two solar panel options for home solar energy systems. We’ll list these below and include a brief description of each to help you decide which might be right for your home.

Q Cells also only has two solar panels for homes in production at this time. We’d ideally like to see more variety to give solar customers the opportunity to bring down solar panel installation costs or push up performance.

Ultimately, that could mean you’d need to replace your system sooner to ensure production keeps up with consumption. Additionally, the maximum efficiency currently available from the company is 20.9%. While this is above the industry standard, we’d love to see an efficiency rating topping 21%, like most of Q Cells’s direct competitors.

While Q Cells matches SunPower in terms of first-year efficiency degradation, the efficiency loss per year after that is a bit higher. That means Q Cells panels won’t perform as well as SunPower’s over time, so your production will be significantly lower by the end of your panel’s life.

Finally, and most importantly, Q Cells panels average around $3.00 per watt, as compared to comparable brands that average around $3.30 per watt. On a 10kW system, that’s an average potential savings of $3,000 on your entire system, which is substantial and can significantly lower your all-in cost of going solar.

Its panels also come rated to withstand 4,000 pascal units on the rear of the panel, which means it’s better than most for areas that see strong winds and will help prevent mishaps and costly replacements.

Q Cells offers robust warranty coverage for performance and manufacturer defects that’s in line with the industry average of 25 years each. This will prevent you from having to carry out expensive repairs and should help avoid your production dipping below your consumption within the first two decades of operation.

It matches SunPower in terms of first-year solar panel degradation as well, so the efficiency over time is going to be better than you’ll see from many competitors. Ultimately, that means your panels will continue serving you and providing savings for many years to come.

Q Cells panels get a lot of things right, including an average efficiency that’s around the industry average. That means your panels should generate plenty of electricity to offset your utility bills and reduce your carbon footprint.

Q Cells, which is a brand manufactured by Hanwha, is the best solar company for value, in our opinion. Despite being more affordable than most other tier-one solar panel brands at around $3.00 per watt, its panels still have above-average efficiency ratings and performance specs. They’re not quite as impressive in their durability as some other options, but they’re still an outstanding choice for many solar customers.

The company has no specific relationships with installers, so any company that can pass certification tests from SunPower can install its products.

SunPower used to manufacture its own panels and outsource installations to third parties. The company went through a restructuring recently, and now its sister company Maxeon handles manufacturing. SunPower still outsources most of its installations, but it has started to complete some with an in-house team.

All SunPower panels include a 25-year workmanship warranty, which is more than double the industry standard. You also get 10 years of roof leak coverage, which most providers don’t offer at all.

As mentioned above, SunPower provides the top solar panel warranty in the entire industry for residential panels. The Maxeon lineup comes with an incredible 40-year warranty for the equipment and panel efficiency. The Performance models include a 25-year warranty for power production and manufacturer defects. These warranties cover most issues with your panels and guarantee that the efficiency loss over time will be minimal.

SunPower has two product lines available: the Maxeon lineup and the Performance lineup. We’ll include a breakdown of all of the panel options within these product lines below.

Still, we think the higher price is worth it for the durability and greater performance, which could actually end up saving you money on energy costs over time.

The only real downside when it comes to SunPower panels is the cost. These panels average over $4.00 per watt, which means a typical 9 kW system will cost around $6,000 more than if you bought competing panels priced at the average cost of $3.33.

SunPower panels mostly come in entirely black models and never have visible grid lines, so they’re a sleek option that most solar customers don’t mind mounting to their roofs. These options are preferred by most homeowners, as they look more modern.

SunPower panels also come backed by an industry-leading 40-year warranty, which is around 60% higher than the standard 25 years of coverage. That means your upfront investment is better protected, and your panels will continue saving you money for longer, improving their overall value. The production warranty guarantees a below-average efficiency loss of 2% in the first year and about half of the loss per year after that. Ultimately, these panels provide more peace of mind that your electric bills will remain low or even non-existent.

First and foremost, SunPower panels reach real-world efficiency ratings of up to 22.8% , which is the highest in the industry. Greater efficiency means improved savings on your utility bills, a faster panel payback period and more value overall from your clean energy system.

Ultimately, we recommend SunPower panels for anyone who wants the highest level of performance and doesn’t mind paying a bit more for it. It’s likely that you’ll save more over time on your energy bills with these panels because of the higher efficiency rating, which should help offset the upfront cost.

The panels from SunPower and its sister company, Maxeon, are considered some of the best in the entire industry by customers and solar professionals alike. SunPower has set the record for the highest panel efficiency available, which translates to greater savings in the long run, and the performance specifications and warranty coverage also outclasses just about every competitor. These panels are expensive, but we feel they’re worth it.

What Should You Look for When Choosing Solar Panels for Your Home?

Since there are so many panel options available from a massive selection of manufacturers, it’s important to focus on the aspects of the panels that will affect you the most. Prioritizing the below features, which we believe are most important for panels for your home, will likely provide you with the best experience and energy savings possible. Unfortunately, not choosing the right panels can lead to a solar energy system that doesn’t save you as much over time.

Compare the Top-Rated Residential PV Panel Manufacturers

For most homeowners, we believe panels from SunPower and Q Cells should meet and exceed expectations. Both solar companies provide panels with excellent performance specifications that can perform well in virtually all climates and weather conditions. We’ll compare the panel options from these companies overall in the table below to help you decide which might be right for your solar project.

Efficiency Score (Out of 25) Durability Score (Out of 20) Warranty Score (Out of 20) Price Point Score (Out of 20) Temperature Coefficient (Out of 10) Sustainability Score (Out of 2.5) Appearance Score (Out of 2.5) Our Overall Rating (Out of 100) SunPower 25.0 19.0 20.0 6.0 10.0 1.9 2.3 84.1 Q Cells 23.0 17.0 16.0 16.0 7.0 1.9 2.5 83.4 Trina Solar 23.0 15.5 16.0 14.0 7.0 1.9 1.5 78.9 REC 25.0 13.0 16.0 10.0 7.0 1.9 1.8 74.6 Panasonic 17.5 16.5 16.0 8.0 10.0 2.5 2.0 72.5

Some other considerations for solar equipment, in addition to the five we’ve reviewed above, include Canadian Solar, Tesla and Silfab.

See Also: EcoWatch Solar Calculator – Calculate Your Home Solar Energy Savings

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What is the Best Type of Solar Panel for Your Home?

When shopping for solar panels, it’s also helpful to know the panel types that are available. The three basic solar panel categories are monocrystalline, polycrystalline and thin-film. Each type of solar panel comes with its own list of pros and cons:

Monocrystalline Solar Panels

Monocrystalline panels are made from a single, pure crystal of silicon. This allows them to have higher efficiency levels, which means they’ll generate more power and offset more of your electricity bills over time. They also tend to be more expensive due to a more costly manufacturing process.

Note: If you have less space on your roof and can only fit a small number of panels, monocrystalline solar panels may be the only viable option that saves you money in the long run.

Polycrystalline Solar Panels

Polycrystalline solar panels are also made of silicon, but they are assembled from smaller fragments rather than a single crystal. This means polycrystalline solar panels are often a little less efficient than monocrystalline, which means they will, on average, save less on your electric bills over time.

They are also a more affordable option, so they’re usually preferred by homeowners looking to keep upfront conversion costs down.

Thin-Film Solar Panels

Finally, thin-film solar panels can be made from a variety of ultra-thin materials. They are recommended when you need something that’s lightweight, flexible and portable; they may work better for RVs and camping than for homes. Thin-film panels can be relatively low in efficiency when compared to the other two options.

These are not recommended for home use, as they efficiency often isn’t high enough to offset the electricity consumption of an entire home.

Do Top-of-the-Line Solar Panels for Homes Still Require Maintenance?

When weighing the pros and cons of going solar before making an investment, one of the most common questions that homeowners have is whether their solar panels will require maintenance.

For the most part, all the hard work comes on the front end. Installing a home solar panel system requires in-depth knowledge of electronics as well as solar power, and in most cases, the installation process will take a few days. We recommend outsourcing this to trained solar professionals.

Once your system is in place, however, the level of upkeep required is fairly minimal. Besides routine cleaning, you shouldn’t have any issues that require maintenance with your solar panels for 20 to 30 years. And if you do run into an issue, your warranty will hopefully cover it.

Solar warranties usually cover performance, manufacturer defects, the installation labor, or all three. Our recommendations for solar panels for homes include robust warranty coverage that should keep you insulated from repairs and expensive maintenance for decades.

Watch Below: If you are just beginning to explore the solar industry, you may want to spend a few minutes familiarizing yourself on how solar cells even work. In the below video, the TED team describes just that.

What Impacts the Performance of Residential Solar Panels?

Solar panels can vary quite a bit in their overall performance and productivity. There are a number of specific factors that can impact how your solar system performs, including:

• Orientation: When your home solar system is designed, your installer will be careful to position each solar panel in a way that maximizes its exposure to sunlight. If the orientation is even a little bit off, it can compromise the efficiency of your entire system. Panels should face toward the sun (to the south, usually, in the U.S.) and should be positioned at the right angle to get the most direct sunlight. Orientation is based on the direction your home faces, the roof pitch, and your latitude.
• Weather and sun exposure: If you live in a part of the country that doesn’t get consistent sunlight, or if your solar panels are often under cloud coverage, you’re not going to produce as much clean energy for your home. (There is a reason why solar panels are especially popular in the Sun Belt.) You might need to choose a higher-efficiency option like SunPower to maximize production, which is more likely to offset your electric bills even in cloudy or shady conditions.
• Cleanliness: While solar panels are fairly low maintenance, you may occasionally need to wipe them down, especially in the aftermath of an intense storm or during a season like spring or fall when there is pollen or falling leaves that can block your panels. If panels become covered with grime or debris, they may not be able to absorb as much sunlight.
• Shade: Keep in mind that any shade cast over your roof is going to impact the efficiency of your solar panels. If your house is surrounded by tall trees, for example, that could impede solar production. If part of your roof sees partial shade, you may need a panel with a higher efficiency rating to compensate for the losses.

Bottom Line: What’s the Best Residential Solar Panel for You?

Our top recommendations for residential solar customers are the panels from SunPower/Maxeon. This manufacturer has a long history in the solar industry and is known for its innovations and solar technologies that push the envelope in terms of efficiency, performance, durability and overall quality. SunPower panels are expensive, but we feel they’re well worth the investment if you can afford them.

Regardless of which panel brand you choose, we recommend getting multiple quotes from a few different solar installation companies in your area. Even if you opt for the same panel brand from multiple installers, your total solar panel system price can be wildly different due to individual pricing for labor and any discounts offered on the equipment. You can use the solar quote tool below to get multiple quotes customized for your home.

The cost information presented in this article is derived from a comprehensive analysis, incorporating data from multiple industry sources. The average cost per watt per state was calculated based on figures from Consumer Affairs, Energy Sage, and Berkeley Lab’s Electricity Markets & Policy Department. Additionally, monthly energy consumption and the average monthly cost of electricity were sourced from the U.S. Energy Information Administration, ensuring a well-rounded and accurate representation of the information presented.

Methodology: How We Reviewed Solar Panels for Homes

In our solar panel review process, we first narrowed our research to the panels that are intended for and available for residential applications. To ensure you understand how we ranked the panels we’ve reviewed above, we’ll include a breakdown of how we scored these panels below.

• Efficiency (25%): First, we considered the efficiency rating and performance of each panel, as these are some of the biggest determining factors when it comes to long-term energy savings. One of the most significant appeals of renewable energy systems for customers is that panels will often pay for themselves and continue saving money after that, and better efficiency ratings and stats tend to reduce the payback period and boost savings over time.

• Durability (20%): The degradation rate in the first year and subsequent years is another crucial factor that determines the longevity of your panels and your savings in the long run. The faster a panel degrades, the less it will save you on your electric bills year after year. Panels with a higher starting efficiency aren’t always going to save you more if the degradation rate is also high.

• Warranty coverage (20%): Next, we look at the warranty coverage to make sure that your panels will continue performing and saving you money for years after installation. The specifics of the warranty—like degradation—are also considered for longevity and long-term panel performance.

• Price Point (20%): Since a solar array is likely to cost you over $20,000 before incentives like the federal solar tax credit (ITC), the cost per watt of a panel is always going to be important. We consider the price per watt in relation to the overall quality and performance to determine the panels that are likely to have the highest return on investment (ROI) over time, especially if you don’t have access to net metering.

• Temperature Coefficient & Adaptability (10%): To determine how adaptable a panel is for multiple climates and living situations, we look at a few things. First, the temperature coefficient tells us how suitable a panel is for hot climates. Second, we look at maximum snow and wind loads to determine if a panel is a good option for all areas throughout the country or if it is limited to areas that don’t see above-average snow and extreme weather.

• Sustainability (2.5%): As an environmentally conscious website, EcoWatch is concerned with how sustainable a panel manufacturer is overall. We do our best to promote panels that use recycled materials and manufacturers that have end-of-life recycling programs for their products.

• Appearance (2.5%): Finally, we know homeowners prefer panels that are all black and don’t have unappealing grid lines that are visible. We rank manufacturers based on how many of their panel options fit these criteria.

Expert Advice on Residential Solar Panel Efficiency

The EcoWatch team polled a number of experts on what homeowners need to know when it comes to getting the most out of their panel. Below are their answers.

Dr. Greg Poelzer, University of Saskatchewan

Dr. Greg Poelzer is a Professor in the School of Environment and Sustainability (SENS) at the University of Saskatchewan. He was the Co-Lead of the Fulbright Arctic Initiative III program. He is the Co-Director of a multi-million dollar SSHRC Partnership Grant (2019-2026), Community Appropriate Sustainable Energy Security (CASES), which spans 17 Indigenous and Northern communities across Canada, Alaska, Norway, and Sweden. He also is the Lead of the Renewable Energy in Remote and Indigenous Communities Flagship Initiative at the University of Saskatchewan and Lead of the UArctic Thematic Network on Renewable Energy.

What is the most efficient solar panel you can buy for homes?

As of 2022, monocrystalline solar panels remain the most efficient option for residential solar photovoltaic (PV) systems when compared to polycrystalline and thin-film technologies. However, the majority market share of polycrystalline panels indicates that many consumers are willing to accept a slightly lower efficiency for a lower cost.

Technological advancements in thin-film PV research are also rapidly pushing this lighter, more flexible and less temperature-sensitive option to achieve efficiency levels that rival the mono- and polycrystalline systems. But prices will likely have to come down significantly to make this an attractive option to consumers for residential systems.

Does solar power work in cloudy weather?

Since clouds are not entirely opaque, sunlight still passes through them and reaches solar panels. The electricity generated may be lower than on days without clouds, but there is a significant difference between the sunlight that is diffused through cloud cover versus sunlight that is blocked by solid objects like tall buildings.

Do shade and temperature affect solar panel efficiency? How do I know if my roof is good for solar?

To determine whether solar panels are a good fit for your home it is important to have an assessment of the solar irradiance (i.e. the amount of sunlight) of your roof. Solar irradiance can be affected by environmental and physical factors. These may include hours of sunlight based on weather conditions and latitude, whether your roof faces south in the northern hemisphere or north in the southern hemisphere, and obstructions such as tall trees and buildings that shade your roof.

Dr. Sharon Klein, University of Maine

Dr. Sharon Klein is an Associate Professor and the Graduate Program Coordinator in the School of Economics at the University of Maine. She has a Bachelor of Science in Environmental Science from the University of Massachusetts, Amherst, and a Ph.D. in Engineering and Public Policy from Carnegie Mellon University.

What is the most efficient solar panel you can buy for homes?

In general, crystalline solar panels are more efficient than thin film. However, there are a variety of specific technologies that fall under the umbrella terms “crystalline” and “thin film.” Also, researchers are pushing the limits of solar efficiency every day. For example, researchers at the National Renewable Energy Laboratory (NREL) recently created a solar cell with a record 39.5% efficiency. That type of efficiency is not yet being seen in residential solar. Most residential solar panels are mono- or poly-crystalline, with efficiencies that range from 15-23%.

Does solar power work in cloudy weather?

Yes. Although solar panels work best in direct sunlight, they can also work when light is reflected or diffused through clouds. However, when it is cloudy, solar panels will not be operating at their maximum efficiency. They may only be operating at 10-25% efficiency, depending on how dense the clouds are.

Do shade and temperature affect solar panel efficiency? How do I know if my roof is good for solar?

Yes. Shade will act like a cloud, diminishing the efficiency of the solar panel. Solar operates best in cooler temperatures. High temperatures reduce the efficiency. The best way to know if your roof is good for solar is to ask for free quotes from multiple local solar installers. They will be able to tell you exactly how many panels, of what type, your roof can support, whether any tree removal is necessary, and how much it will cost and you will save.

Hao Zeng, University at Buffalo

Hao Zeng is a professor of physics at the University at Buffalo, the State University of New York. His main research area is in condensed matter and materials physics. He has a strong interest in developing novel magnetic and semiconducting materials for renewable energy applications. He has published about 150 scientific papers with a total citation of 20,000 times according to Google Scholar.

What is the most efficient solar panel you can buy for homes?

For residential solar panels, the most efficient ones are monocrystalline Si, with an efficiency of 20%~ 22%. As of July 2022, the SunPower Maxeon 6 boasts a panel efficiency of 22.8%. This is followed by polycrystalline Si with a panel efficiency close to 20%. Panels made from thin films such as CdTe from First Solar are generally less efficient ~ 18%. They are used primarily for commercial and industrial applications due to the low fabrication cost. There are other types of thin film solar technology such as those based on CuInGaSe2 and perovskite materials. They have not yet seen large-scale commercial deployment.

Does solar power work in cloudy weather?

Solar panels do work in cloudy weather. However, they are less efficient in such conditions. The output power drops roughly linearly with light intensity. Depending on the cloud cover and the types of solar panels, efficiency can drop by 10 to 25 percent of the specified values.

Do shade and temperature affect solar panel efficiency? How do I know if my roof is good for solar?

Shade and temperature do affect solar panel efficiency. Shade means direct sunlight is blocked by e.g. trees, reducing the intensity of the light hitting the surface of the solar panel, thus reducing efficiency. On the other hand, efficiency of the solar panel decreases with increasing temperature. This decrease in performance is called temperature coefficient, which ranges typically from -0.3 to -0.5%/degree C. This means that the efficiency will drop by 0.3-0.5% for every degree Celsius increase in temperature. The amount of electricity generated by rooftop solar panels depends on the orientation and tilting angle of the roof. The best roof angle for solar panels is about 30 degrees. In the northern hemisphere, the best orientation of the roof is south-facing. Needless to say, your roof used for solar panel installation needs to be subjected to minimal shading throughout the day.

Mohammad E. Taslim, Northeastern University

Mohammad is a professor of mechanical engineering at Northeastern University. He is also the program director of the Energy Systems Program. He is an ASME Fellow, AIAA Associate Fellow and a member of the editorial board of the International J. Heat Exchangers.

What is the most efficient solar panel you can buy for homes?

The most efficient is monocrystalline. From the name, each cell is cut
out of one type of silicon. The other two are less efficient and the thin-film is less expensive.

Does solar power work in cloudy weather?

Yes, solar energy reaches the earth in form of waves at wavelengths from infrared to ultraviolet. Only about 46% of that energy is in the visible range (red to violet). The rest is outside the visible range that can reach earth through the clouds.

Do shade and temperature affect solar panel efficiency? How do I know if my roof is good for solar?

Yes, a target surface directly exposed to the sun is much more efficient. Shadows cast on the target surface from the trees, billboards, adjacent buildings, etc. seriously reduce the absorption of solar energy by the target surface. For any surface on earth, there are software tools to determine how many hours on a given day of the year (in the northern or southern hemisphere) the surface is exposed to the sun (sees the sun) as the sun travels across the sky. And, with the knowledge of adjacent buildings’ elevation and size, we can determine if they cast any shadow on the panels and for what period of time. As for the temperature effects, the higher the solar panel temperature, the lower its power output. An ideal ambient temperature around the solar panels is 77 degrees F.

Nathan S. Lewis, California Institute of Technology

Nathan S. Lewis, Ph.D., is the George L. Argyros Professor of Chemistry at Caltech. Lewis is best known for developing artificial photosynthesis technology that enables sustainable production of hydrogen fuel using sunlight, water and carbon dioxide. Research interests include phototropism in the non-biological inorganic matter and related pattern-free nanoscale 3-D lithography. Lewis is also interested in weather-based data-driven modeling of deeply decarbonized electricity and energy systems based on variable renewable energy and technologies for long-term grid storage.

What is the most efficient solar panel you can buy for homes?

Generally, monocrystalline cells from SunPower are the most efficient panels due to their unique technology (but they generally cost more as well). They have a lot of value for limited areas because the higher efficiency means that one can make more electricity from a small roof than can be made from lower efficiency panels, to help meet the electricity demand of a household in full.

Does solar power work in cloudy weather?

Yes, solar panels work in cloudy weather, but not as much electricity is produced when clouds reduce the amount of sunlight striking the panels as on a bright sunny summer day.

Do shade and temperature affect solar panel efficiency? How do I know if my roof is good for solar?

The efficiency isn’t affected by shade; the panels still convert the same percentage of sunlight into electricity except that the amount of sunlight available is less so less electricity is produced

Almost all panels exhibit lower efficiency as the temperature increases.

Panels also get warn from absorbing all of that nice sunlight; if one could keep them cool on a bright, warm, sunny day they would work better but that is obviously hard to do without using some of the electricity that they make for “air conditioning” the panels themselves and it isn’t worth it generally to spend more electricity to cool the panel than they produce as a result of running cooler rather than warmer. Using water to cool the panels generally isn’t a good idea because water and all of that electricity “don’t mix” from a safety perspective in most localities.

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