Top 7 Best 400-Watt Solar Panels in 2025 (Cost, Specs & More)

What is a 400-Watt Solar Panel?

The “watt” is a unit of power, denoting the amount of energy consumed or generated in an hour. For instance, a 50 watt LED bulb consumes 50 watts of power every hour. Similarly, a 400 watt solar panel generates up to 400 watts of power with every hour of direct sunshine. Therefore, a 400 W panel can ideally run 80 of the above-mentioned LED bulbs (50 W x 80 = 400W).

The polycrystalline solar panels from the older generations were far less efficient than today’s monocrystalline options, and could generate much less power in the same size. This is why 250 or 300 watts were the largest panel sizes until just a few years ago.

Speaking of solar panel sizes, most solar panels have 60 or 72 silicon cells in them. Any more than that and the panel weakens under its own weight. This makes the power rating so important, because all manufacturers have to maximize the power output in the available size limits.

Typically, 300 to 360 W panels (60 cells) are still used in residential applications, although panels pushing up to 400 to 500 W panels (72 cells) are also not uncommon. Commercial solar systems usually use panels between 450 and 650 watts.

What is the Best 400-Watt Solar Panel?

The last couple of decades have seen an incredible boom in solar panel manufacturing companies. The result of this is a wide variety of solar panel options to choose from. And with all the available options in the 400 W category, it is difficult to shortlist a few panels as the best options, let alone choosing a single panel as the best one.

All the solar panels we have selected have something unique in them — from aesthetics and innovative tech to cost and efficiency. The panel that is best for you will depend on several factors, and your own preferences.

However, if we had to choose just one “overall best 400 W panel,” we would award the title to Maxeon’s Maxeon 3 panel — just a note that Maxeon used to be SunPower and is not a sister company of SunPower. It offers the highest efficiency in its class, while also offering microinverters and some cutting-edge solar cell technology.

Compare 400-Watt Panels At A Glance

Maxeon 3 Series – Best Overall

Maxeon’s state-of-the-art 3 series residential solar panel offers an impressive efficiency of 22.7%, which is the highest in the industry. It houses larger mono-Si solar cells and comes with integrated microinverters supplied by the industry-leader Enphase.

• • Price: $4.25/W
  • Dimensions: 71.3 x 41.2 x 1.57 in
  • Weight: 46.7 lbs.
  • Where to buy: Through authorized installers

Pros and Cons of Maxeon 3 Series

Pros:

• High efficiency
• Integrated microinverters
• Industry-leading warranty

Cons:

• Expensive

Read our review of Maxeon solar panels

Silfab Elite SIL-410 BG – Best Aesthetics

Labeled by the maker as “America’s most beautiful panel,” the Elite SIL series comes with a sleek, all-black look, thin profile and superb efficiency numbers. The panel’s innovative conductive backsheet and integrated cell design make it stand out in terms of performance as well as looks.

• Price: $3.90 – $4.50/W
• Dimensions: 73.4 x 40.5 x 1.4 in
• Weight: 45.8 lbs.
• Where to buy: Through authorized Silfab installers

Pros and Cons of Silfab Elite SIL-410 BG

Pros:

• High efficiency
• Exceptional aesthetics
• Excellent warranty
• Made in the U.S.A.

Cons:

• Slightly expensive

Q Cells Q. Peak Duo BLK ML-G10+ – Best American Made

Q Cells is one of the oldest and most respected solar power companies and one that has ramped up production in the U.S. at a gigantic scale. This large-scale production allows Q Cells to offer high-quality, feature-packed panels at reasonable costs, and the Q. Peak Duo is no exception.

• Price: $3.50 – $3.90/W
• Dimensions: 74.0 x 41.1 x 1.26 in
• Weight: 48.5 lbs.
• Where to buy: Through authorized Hanwha Q Cells installers — Momentum Solar, Palmetto Solar and Trinity Solar.

Pros and Cons of Q Cells Q. Peak Duo BLK ML-G10+

Pros:

• High efficiency
• Excellent warranty
• Highly reliable brand
• Made in the U.S.A.

Cons:

• Q Cells went bankrupt in 2012, but was then brought out by The Hanwah Group — a large South Korean business conglomerate. The company has been stable since, but it’s worth calling out.

Read our review of Q Cells solar panels.

Mission Solar MSE PERC 60 BLK – Most Affordable

Texas-based Mission Solar has quickly risen to be one of the most popular local solar companies. Its MSE series offers high-quality PERC modules at a reasonable price tag, which also come with decent efficiency and positive power tolerance of 0 to 3%.

• Price: $3.00 – $3.40/W
• Dimensions: 65.98 x 39.68 x 1.38 in
• Weight: 44 lbs.
• Where to buy: Through Mission Solar or authorized installers

Pros and Cons of Mission Solar MSE PERC 60 BLK

Pros:

• Low cost per watt
• Made in the U.S.A.

Cons:

• Not as reputed as others on this list

Read our review of Mission Solar panels.

Canadian Solar HiKu dual cell PERC CS3N400 – Most Value for Money

Canadian Solar is one of the oldest solar module manufacturing companies. Its HiKu series is popular, and the dual cell PERC module brings all the essential modern tech to a reasonable price slab.

• Price: $3.00 – $3.80/W
• Dimensions: 76.4 x 41.3 x 1.38 in
• Weight: 49.6 lbs.
• Where to buy: Through Canadian Solar or authorized installers — Momentum solar, Blue Raven Solar

Pros and Cons of Canadian Solar HiKu dual cell PERC CS3N400

Pros:

• High efficiency PERC technology
• Reliable brand
• Low LID losses

Cons:

• Ordinary design

Solaria PowerXT Pure Black – Best Warranty

Solaria’s proprietary Pure Black technology enhances both solar panel aesthetics and performance. The PowerXT panel crosses the 20% efficiency barrier and comes with a 30-year warranty. Solaria was recently purchased by Maxeon, so the warranty coverage you get for those 30 years now rivals the best in the business.

• Price: $2.75 – $3.25
• Dimensions: 64.72 x 47.4 x 1.57 in
• Weight: 46 lbs.
• Where to buy: Through Solaria’s partner installers

Pros and Cons of Solaria PowerXT Pure Black

Pros:

• High efficiency
• Solder-less design
• Exceptional 30-year warranty
• Low PID losses
• Innovative, no busbar design

Cons:

• Limited buying options

EcoFlow Foldable 400 W Solar Panel – Best Portable

A highly popular name in portable solar products, EcoFlow is the only reputed brand that offers a single, foldable 400 W solar panel (unlike Renogy’s multi-solar-panel kit). The panel impresses not only with its portability but also with its high efficiency and thoughtful design, making it perfect for DIY and off-grid installs.

• Price: $1,199 (per-watt system pricing not applicable)
• Dimensions: 42.0 x 94.1 x 1.0 in
• Weight: 35.3 lbs.
• Where to buy: Through Amazon or EcoFlow’s official website

Pros and Cons of EcoFlow Foldable 400 W Solar Panel

Pros:

• Foldable and lightweight design
• High efficiency
• Integrated and adjustable mounting kickstand
• Highly durable, glass-free structure
• Plug-and-play design

Cons:

• Unimpressive warranty
• Expensive

How Much Do 400-Watt Solar Panels Cost?

The easy answer: it depends on the brand of the 400W solar panel.

Modern solar panels that share the same power rating may not share the same features and, consequently, the same pricing. As expected, the more innovative and technologically-advanced solar panels typically cost more than simpler models.

The cost of solar panels rated for 400 W output can be anywhere between $3 and $5 per watt installed. Remember that this is the price of the entire solar power system, installed using a number of 400 W mono solar panels together.

We cannot state the price of an individual 400 W panel, since it is generally difficult to source only the solar panels (unless you are an authorized installer yourself, in which case you likely wouldn’t need to read this article). However, the average price per watt in the U.S. for PV panels is $3.33, using data from a variety of sources, so that puts the average cost of a single 400-watt panel at around $1,332.

Like any other product, it’s important to remember that cost alone should not be the deciding factor when choosing 400 W panels. Oftentimes a more costly panel can save you a lot more money over its lifespan. Or, a panel with stronger warranties can offer more reliability than a cheaper panel with short warranties.

The best way to choose a 400 W solar panel is to narrow down your needs and preferences and choose the product that has the optimum balance between cost, features, efficiency and warranty.

How Much Energy Will a 400-Watt Solar Panel Produce?

While most homeowners will naturally want to know how much solar energy each 400-watt panel they install on their homes will produce, the answer is a bit complicated.

The rating on your PV module in wattage tells you the maximum amount of energy it can generate with full, intense sunlight. This measurement of power output is called the Standard Test Condition (STC).

However, in reality, there are many factors that affect the panel’s efficiency and power production. Some of the factors that affect your production are shown below:

• The direction your panels face
• The intensity of the sunlight that hits the panels
• The hours of daylight in your area
• The weather, including the average number of cloudy days per year
• Shading on your property from trees or nearby buildings
• The brand of the panel you choose and its maximum efficiency
• The age of your panel, as they lose efficiency over time

For a baseline production, you can use the calculation below, but remember that this estimate can change drastically based on the factors above:

Your Daily Watt-Hours per Panel = [average hours of sunlight] x [solar panel wattage] x [75% maximum power production to account for changing weather conditions and lower sun intensity in the morning and afternoon]

Your Daily Kilowatt-Hours (kWh) per Panel = [your daily watt-hours] / 1,000

If we assume that your area receives six hours of sunlight every day, we can use the above equation to calculate how much power each 400-watt panel on your property will produce on a daily basis.

[6 hours of sunlight] x [400 watts] x 75% = 1,800 watts per day

[1,800 watts per day] / 1,000 = 1.8 kWh per day

Remember, this should be considered as maximum production, and the factors mentioned above can bring this number down significantly. If we assume maximum production, you’re looking at 1.8 kWh of energy production every day, which equates to 657 kWh per year per 400-watt panel.

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How Many 400-Watt Solar Panels Do I Need to Power My Home?

Based on our above calculation of annual energy production from a 400 W solar panel, we can calculate how many panels your home will need.

For example, if your home consumes the national average of 10,572 kWh per year, you’d need 13 400-watt panels to power your home. The calculation below explains why.

[10,572 kWh of energy needed] / [876 kWh of production per panel] = 12.06 panels, which gets rounded up to 13 panels

Don’t feel like whipping out your calculator? No worries. You can use our solar calculator to find out how many solar panels you need to power your home.

Keep in mind that solar panels alone cannot power a home. You will need other supporting components — such as an inverter, branch connectors, tray cables, z brackets and more. If you want to store your solar energy for later, you’ll also need solar batteries and an MPPT solar charge controller.

Maybe you’re not looking to power your entire house and are instead wondering what a single 400 W panel can run. Thankfully, this is simpler to find out. The “watt” rating denotes not only the power generated, but can also denote power consumption rating on appliances.

All you need to do is check the rating on an appliance and make sure it is lower than that of your solar panel. In this case, anything that consumes less than 400 W of power can operate on a 400 W solar panel. A few examples of this are listed in a table below:

Roof Space Requirements for 400-Watt Solar Panels

When you are installing a complete solar power system, the roof space required for your system depends more on the total system size than the individual panel size.

As a thumb rule, every kilowatt (kW) of a solar power system requires about 75 square feet of space. Therefore, a typical 11 kW system may need around 825 sq. ft. of roof space. But if we had to calculate using 400 W panels only, here’s how we could do it:

A typical 400 W solar panel is about 75 x 45 inches in dimensions, which is about 25 square feet. An 11 kW system will need about 13 solar panels rated 400 W. This gives us,

25 sq. ft./panel x 13 panels = 325 sq. ft.

Add another 20% to this to account for the space required for safe racking, combiner boxes, wiring and the space left between panel strings to avoid shading. Thus we have:

325 x 120% = 390 sq. ft.

It is important to remember that these are basic calculations and general thumb rules which may or may not apply in every case. Based on the complexity of your roof and other factors encountered in solar installations, your system may need more, or sometimes less space. That’s why it’s best to connect with an experienced solar installer to figure out your solar needs.

Methodology: How We Ranked the Top 5 Best 400-Watt Solar Panels

To stay impartial, our solar experts evaluate hundreds of solar manufacturers in our database based on the same range of criteria and assign scores to each category. The main factors we assessed to find the best 400-Watt solar panels include:

• Cost and ease of purchase (20%): Cost is typically the biggest deciding factor for homeowners going solar. Obviously, solar panels at 400W are going to be more expensive than 250W or 350W panels because they’re stronger, but we still look for companies that offer reasonable prices for the quality. Companies with the most transparent, economical and practical financing options also scored highest in this category.
• Warranty coverage (15%): Solar panel manufacturers offering longer, more comprehensive warranties performed better in this category.
• Experience (15%): Companies with less than 10 years of solar manufacturing experience are docked in this category. Most with less than five were deemed not eligible for ranking.
• Availability (15%): Solar panel brands that are available to a larger number of customers scored higher in this category.
• Reputation (15%): We analyze reviews and trends on Google reviews, the Better Business Bureau (BBB) and similar review sites and assign scores accordingly.
• Solar services (20%): Manufacturers with more comprehensive service offerings perform better in this category. We also assess the quality of the products that the provider installs.

For a more in-depth look at our methodology, you can visit our solar rankings page.

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.