Best 400-Watt Solar Panels: Cost, Specs & Everything You Need to Know

Here’s what you’ll learn in this guide:

  • The best 400-watt solar panels on the market
  • What a 400-watt solar panel can power
  • How much you might pay for this size of the panel
  • 400-watt panel specs
Ecowatch Author Dan Simms

By Dan Simms, Solar Expert

Updated 8/3/2022

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Solar technology has advanced rapidly in the past few decades, which means there are now plenty of options for your home, RV, boat, or other on- or off-grid solar project. Many homeowners choose 400-watt (W) panels, which provide a nice blend of affordability and efficiency. 

However, with an increasing number of panel and brand options, choosing the right one for your budget and energy needs can be a challenge. In this guide, we’ll discuss our top picks for solar panels in the 400W range, their warranty coverage and overall cost, how many you need for your home, and more.

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Jump To: What Are the Best 400-Watt Solar Panels? | Panel Pricing | Warranties | Panel Specs | How Much Energy Will a 400-Watt Solar Panel Produce? | What Can a 400-Watt Solar Panel Run? | What Factors Influence Power Output? | How Many 400-Watt Solar Panels Do I Need?

What Are the Best 400-Watt Solar Panels Available?

Many of the solar panels you’ll see in residential solar projects are between 400 and 500 watts, so many of the major solar manufacturers — like SunPower Solar, Panasonic, LG, and Tesla — produce several options in the 400W range. There are also some solar kits available for DIY installation, so we’ll include one in case you prefer to do your own installation. Below are our top picks for 400W panels.

  • Best Overall: SunPower A Series Residential Monocrystalline Solar Panels
  • Best Warranty: SunPower SPR-E20-435-COM 435-Watt Mono Solar Panels
  • Best Value: Canadian Solar HiKu Mono PERC Series Solar Panels
  • Best Durability: LG High-Efficiency LG NeON 72Cell Module Cells LG400N2W-A5 Solar Panels
  • Most Affordable: Mission Solar Energy (MSE) MSE PERC 72 SX6W 405 Solar Panels
  • Best for DIY Installations: Renogy 400-Watt 12 Volt Solar Premium Kit
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400-Watt Solar Panel Pricing

Smaller solar panels — usually in the 300-watt range — are more geared toward DIY solar panel installers and small-scale renewable energy projects, and they’re sold by retailers at standard prices in solar panel kits. Once you get up into the 400-watt range, solar panels are still meant for residential and other individual consumer purposes, but they’re more often installed by professionals and the panel cost is included in the total cost for a solar installation. Fewer solar starter kits include 400-watt panels. 

The table below provides average pricing on a per-watt basis for an entire solar system (the cost for the DIY kit is not priced per watt).

Solar Panel Average Price Per Watt
SunPower A Series Residential Monocrystalline Solar Panels $3.12 – $3.74
SunPower SPR-E20-435-COM 435-Watt Mono Solar Panels $3.12 – $3.74
Canadian Solar HiKu Mono PERC Series Solar Panels $2.70 – $3.20
LG High-Efficiency LG NeON 72Cell Module Cells LG400N2W-A5 Solar Panels $2.78 – $3.60
Mission Solar Energy (MSE) MSE PERC 72 SX6W 405 Solar Panels (Polycrystalline or Monocrystalline) $2.25 – $2.69
Renogy 400-Watt 12 Volt Solar Premium Kit $799.99 (includes four 400W solar panels, an Adventurer lithium deep cycle battery bank, a PWM charge controller, and Z brackets for mounting)

400-watt solar panel warranty tip

400-Watt Solar Panel Warranties

Solar panels are expensive, so it’s important to protect your investment by choosing a solar panel brand that provides a lengthy warranty. Solar warranties can cover the equipment, the labor or workmanship for the installation, the power production over time or a combination of the three. Longer warranties that cover all aspects of your solar project are, of course, the best option. Panels sold for DIY solar installation will not include a workmanship warranty. The table below provides warranty information for our top five 400W solar panel picks.

Solar Panel Warranty Coverage Included
SunPower A Series Residential Monocrystalline Solar Panels 25-year warranty for equipment and labor, plus a 25-year progressive warranty for power generation (minimum of 85.5% after 25 years)
SunPower SPR-E20-435-COM 435-Watt Mono Solar Panels 25-year warranty for equipment and labor, plus a 25-year progressive warranty for power generation (minimum of 85.5% after 25 years)
Canadian Solar HiKu Mono PERC Series Solar Panels 10-year limited warranty for equipment plus a 25-year limited warranty for power generation (minimum of 80% after 25 years)
LG High-Efficiency LG NeON 72Cell Module Cells LG400N2W-A5 Solar Panels 25-year limited warranty plus 25-year generation warranty guaranteeing a minimum of 90.6% efficiency
Mission Solar Energy (MSE) MSE PERC 72 SX6W 405 Solar Panels 12-year warranty for equipment, or up to 25 years with an extended warranty
Renogy 400-Watt 12 Volt Solar Premium Kit 5-year warranty for equipment and workmanship

Panel Specifications: How Big Is a 400-Watt Solar Panel?

Every solar panel is different, so even panels that come with the same wattage can have varying dimensions based on the number of solar cells, the cell type (like half-cut or full-cell), and their size. The average size of a 400-watt solar panel is 39” by 79” at around 1.4” thick. 400-watt solar panels typically weigh around 50 pounds, making them a challenge to get up onto roofs without the proper equipment. This, along with electrical considerations, is one of the reasons the installation is often left to professionals. The table below provides dimensions and weights for the best solar panels in the 400-watt range.

Solar Panel Product Dimensions (Per Panel) Panel Weight (Per Panel)
SunPower A Series Residential Monocrystalline Solar Panels 40.0” by 72.2” at 1.57” thick 44 lbs
SunPower SPR-E20-435-COM 435-Watt Mono Solar Panels 41.18” by 81.38” at 1.81” thick 56 lbs
Canadian Solar HiKu Mono PERC Series Solar Panels 41.26” by 76.38” at 1.38” thick 49.6 lbs
LG High-Efficiency LG NeON 72Cell Module Cells LG400N2W-A5 Solar Panels 40.31” by 79.79” at 1.57” thick 47.84 lbs
Mission Solar Energy (MSE) MSE PERC 72 SX6W 405 Solar Panels 41.5” by 82.13” at 1.57” thick 50.7 lbs
Renogy 400-Watt 12 Volt Solar Premium Kit 20.9” by 41.8” at 1.4” thick 14.1 lbs each
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How Much Energy Will a 400-Watt Solar Panel Produce?

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

  1. (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 watt-hours
  2. (your daily watt-hours) / 1,000 = your daily kilowatt-hours (kWh) per panel

How Many kWh Does a 400-Watt Solar Panel Produce?

If we assume that your area receives eight 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.

(8 hours of sunlight) x (400 watts) x (75%) = 2,400 watts per day

(2,400 watts per day) / 1,000 = 2.4 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 2.4 kWh of energy production every day, which equates to 876 kWh per year per 400-watt panel. This is often a good place to start when deciding how many panels you need for your project. If your home consumes the national average of 10,715 kWh per year, for example, you’d need 13 400-watt panels to power your home. The calculation below explains why.

(10,715 kWh of energy needed) / (876 kWh of production per panel) = 12.23 panels, which gets rounded up to 13 panels

How Does Solar Irradiance Impact Power Output?

Solar irradiance has a significant effect on the power output of your solar panels and can often be the difference between maximum efficiency and as little as 10 percent efficiency. Solar irradiance refers to the intensity of the sun at a given location. The more directly the sun hits your panels, the closer the energy production will be to the panel’s maximum efficiency. The states that are best for solar power are those closest to the equator, where the sunlight hits at an angle closest to perpendicular, meaning a higher intensity.

Solar irradiance is often measured in kilowatts per square meter, and many solar calculators automatically consider this measurement in your area. You can find online tools to estimate your solar irradiance, although it’s challenging to work this measurement into efficiency calculations accurately, given the other factors. For most homeowners, it suffices to know that areas with higher solar irradiance measurements will generally be a better fit for solar installation and will see higher levels of energy production per 400-watt panel.

Here’s a look into solar irradiance:

Is Panel Voltage Important?

Solar system voltage — including open-circuit voltage (VOC) and short circuit current (ISC) — is an often-overlooked measurement on panel datasheets, but it’s an important one to consider, especially for residential solar applications. It’s easiest to imagine voltage in terms of how liquids behave. Suppose you have a large water tank with a hose leading out of the bottom. When you open the valve to the hose, water will flow out of the hose at a speed (amps) proportionate to the amount of water in the tank (voltage). The more water you have in the tank (your solar panels’ voltage rating), the more force will be exerted at the exit point (batteries or electronic devices).

Everything that uses electricity comes with a voltage rating, which determines how much voltage from your panels is required to power it. For example, an electric stove often requires 240 volts to power, while a 12-volt battery requires just over 12. A solar panel with a rating of 24 volts could supply power to a 12-volt battery, provided you have an MPPT charge controller, but it would fall far short when it came to power the stove. Ultimately, your panel voltage will determine what items your solar array can provide power for. Keep in mind that panels can be run in series using branch connectors to ramp up the voltage to your inverter.

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What Can a 400-Watt Solar Panel Run?

Depending on the voltage required, a single 400-watt solar panel can run most of the smaller electronics and electric devices in your home. The table below provides a list of some of the more common things you can run with a 400-watt solar panel, along with the rated watts of each, which must be met in order to provide sufficient power.

Appliance/Household Item Running or Rated Watts Required to Run
Phone Charger 10 watts
CFL Light Bulb 18 watts
Ceiling Fan 60 watts
Standard 60W Incandescent Light Bulb 60 watts
DVD Player 100 watts
Mini-Fridge 100 watts
Home Speaker System 100 watts
Box Fan or Floor Fan 100 watts
Hair Straightener 120 watts
Laptop Charger 125 watts
Electric Can Opener 170 watts
Gaming Console 180 watts
Vacuum Cleaner 200 watts
Rice Cooker 200 watts
Heated Blanket 200 watts
Up to 56” LCD TV 225 watts
Paper Shredder 225 watts
TV 230 watts
PC (Non-Gaming) 240 watts
Small Dehumidifier 250 watts
Computer Monitor 250 watts
Crockpot 250 watts
Projector 280 watts
Whole-House Exhaust Fan 350 watts
Blender 360 watts
Central AC Fan Only 370 watts
Evaporative Cooler 400 watts
Keurig Coffee Maker 400 watts
Desktop PC and Monitor 400 watts

What Factors Influence Solar Panel Power Output?

As mentioned above, there are quite a few things that affect the power output of your solar panels. One of the most important factors is the amount of sunlight that hits them each day. You’ll need to take into consideration things like the shading on your property from trees or buildings, the number of sunlight hours you receive per day, and the weather. Also important is solar irradiance, which is a measurement of how intense the sunlight is in your area, as this can have a major impact on solar energy production.

The brand of your panels and the rated efficiency also matter, as does the age. Panels gradually lose efficiency as they age, and different brands will start at different levels of efficiency and lose efficiency at different rates. Finally, the direction your panels face — south is the best direction for panels in the U.S., by far — will affect your level of solar energy production.

How Many 400-Watt Solar Panels Do I Need?

When you’re planning on installing solar panels, you always want to know how many panels you need so you don’t end up overpaying for your solar power system or installing a solar array that won’t cover your usage. To determine how many solar panels you need, you can divide your total energy consumption by the total expected production of the panels you intend to install.

For example, if you need to know how many 400-watt solar panels you need to power your home, you can check your past electric bills for average annual usage. The average consumption in America is 10,715 kWh per year. Using our calculations above for an area that sees eight hours of sun a day, you could use the calculation below to figure out how many panels you need:

(10,715 kWh per year) / (876 kWh produced per panel) = 12.23 panels, rounded up to 13 panels

Provided you use solar panels intended for homes, a 10 kWh solar system would require around 13 400-watt panels.

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Dan Simms

Solar Expert

Dan Simms is an experienced writer with a passion for renewable energy. As a solar and EV advocate, much of his work has focused on the potential of solar power and deregulated energy, but he also writes on related topics, like real estate and economics. In his free time — when he's not checking his own home's solar production — he enjoys outdoor activities like hiking, mountain biking, skiing and rock climbing.