400-watt solar panels explained: everything you need to know



400-watt solar panels
Find out if 400-watt solar panels are right for you.

The wattage of a solar panel describes the panel’s output capacity. So, does a 400-watt solar panel produce enough power for your home?

Just a few years ago, the most common panels used on homes were around 300 watts. Now, as technology has continued to develop, most standard-sized residential solar panels are about 400 watts in size. 

In this article, we’ll provide you with everything you need to know about 400-watt panels, brands to consider, the cost, and more. 

What is a 400-watt solar panel?

When you’re describing the size of a panel, it’s usually based on the panel’s power output capacity, measured in watts.

So, a 400 W solar panel is capable of producing 400 watts of instantaneous DC electricity under ideal Standard Test Conditions. 400-watt solar panels typically contain 60 to 66 solar cells and are about 5.4 feet long and 3.25 wide.

Standard Test Conditions, or STC, are a set of lab standards that solar panels are tested at. So, a 400-watt panel will only produce 400 watts of power under these ideal conditions.

Unfortunately, your roof isn’t a lab, so your panel will usually be outputting less power than 400 watts. In the real world, a 400 W panel will typically produce closer to 300 W of power. But don’t worry, solar panel systems are designed with this in mind, so your solar system will still generate the amount of energy needed to power your home. 

How much energy does a 400-watt solar panel produce?

Power and energy are a bit different, and it’s important to understand the difference. We said a 400 W solar panel will generate 400 watts of power in ideal conditions. The amount of energy it produces is how much power is made over a certain period of time.

You can expect a 400-watt solar panel on your roof to generate between 1.2 kilowatt-hours (kWh) and 1.5 kWh of electricity daily.

How much energy a solar panel produces depends on a number of factors, including the environmental conditions and the amount of sunlight your roof gets. The following table outlines how much energy a 400 W solar panel will produce in different areas of the U.S.:

Table 1: Energy produced by a 400 W solar panel in different regions of the U.S.

Region Solar energy produced daily Solar energy produced monthly
North East 1.1 kWh 34 kWh
Midwest 1.2 kWh 37 kWh

South East

1.3 kWh 40 kWh
South 1.4 kWh 43 kWh
West 1.3 kWh 40 kWh

How much does a typical 400-watt solar panel cost?

A high-quality 400 W solar panel will cost between $250 and $300 per panel. This price doesn’t include any other equipment needed to use the panel or installation costs. 

It’s highly unlikely that you would purchase just one solar panel. Installing a full 7 kW solar system using 400 W solar panels would cost a total of $19,950 before any incentives. When you include the federal solar tax credit, that price drops to about $14,000.

The cost can vary with market conditions, your location, the solar panel brand you choose, and the solar installer you choose.

How much do 400-watt solar panels cost for your home?

How many 400-watt panels do I need to power my home?

Most homeowners installing a solar power system on their roof will require between 15 and 30 400-watt solar panels. But exactly how many solar panels you need can vary quite a bit from state to state.

For example, here are how many 400-watt solar panels are needed for the average homes in California, Texas, and Florida:

Table 2: How many 400 W solar panels are needed in different states, on average

State Avg. system size 400-watt panels required Space required
California 7.33 kW 19 panels 417 sq. ft.
Texas 10.32 kW 26 panels 570 sq. ft.


10.75 kW 27 panels 592 sq. ft.

*Assuming each solar panel is 79.8” x 39.6”, does not include access and setback requirements.

Remember that these are just average figures. The right solar system size for your home will be unique to you depending on various factors – like your energy usage, your utility rates, and how much sunlight your roof gets.

Luckily, we have a tool that can help you determine some of these factors. Put your home information into our solar calculator to get a better understanding of your home’s system size.

The best 400-watt solar panels

You may still feel a little lost when thinking of exactly who you should buy panels from. Look no further – here’s a list of some of the best 400-watt panel models from different manufacturers.

Table 3: 400-watt solar panels by the top solar brands

Brand Panel model Wattage What's good
Qcells Q.PEAK DUO BLK ML-G10+ 395 - 415 W

- Reasonably priced

- Made in the U.S.

- Reliable brand

Canadian Solar HiKu6 Mono PERC 395 - 420 W

- Great value

- Solid warranty

- Reliable brand

Mission Solar

MSE-SX9R 390-400 W

- American made

- 9 busbar technology

- Good warranty

SunPower M-series 420 - 440 W

- High efficiency

- Premium quality

- Excellent warranty

REC Group REC Alpha Pure 390 - 410 W

- High quality 

- Operates well at high temperatures

- Excellent warranty

Silfab Solar SIL-400 HC+ 400 W

- High efficiency rating

- Good performance warranty

- Engineered for North American homeowners

Jinko Solar Eagle Contenental 395 - 415 W

- Assembled in the U.S.

- Affordable

- Efficient

We’ve carefully chosen solar panels made exclusively by some of the best and most reputable manufacturers – all of which are ranked on our Top 10 Solar Panel Manufacturers list.

How much money can 400-watt solar panels save me?

You can buy solar panels with your specific energy needs in mind. That could even mean offsetting your electric bills completely!

How much money a 400 W solar panel saves you depends on how much energy it produces, which varies based on where you live. But, on average, one 400 W solar panel produces about $7 worth of electricity daily. 

As we said earlier, you’re not going to install just one solar panel. You’ll want to have enough solar panels to cover most of your daily electricity needs. A typical U.S. home uses about 892 kWh of electricity per month. That equates to a monthly electricity bill of around $143, not including fees or taxes. If you install 21 400 W solar panels, you could potentially save $1,716 in just one year.

Net metering impacts your savings. Net metering is how utility companies bill solar customers for excess solar energy they send to the grid. With true net metering, you get the full retail value for every kWh of solar energy you generate, saving you the most money. However, full-retail net metering is becoming increasingly rare. Without net metering, you likely can’t eliminate your entire electricity bill. But you could still save a decent amount.

What can a 400-watt solar panel run?

Mobile homes and 400-watt solar panels can make a great pair!

In the past, 400 W solar panels used to be considered premium-status panels because they had the highest wattage on the market. Now, there are tons of different solar panel manufacturers that offer bigger and more powerful panels.

Here are a few uses for 400-watt panels:

  • Small-to-large residential homes: Believe it or not, you can still power virtually any home solar panel system with 400 W panels – and a common choice for residential solar.
  • Common household electronics: The average output of a single 400 W panel can power common small electronics, such as televisions, fans, laptops, gaming consoles, and more!
  • RV or boat: Looking to take your solar adventures off-grid? 400 W panels are a perfect pair with a mobile home or boat anywhere and anytime!
  • Appliances: Although they are more power-hungry, you can power appliances such as a microwave, washing machine, or refrigerator with 400 W panels – you may just need more than one!

There are plenty of uses you can get out of 400 W panels, and when you pair it with a good inverter, powering your household is environmentally friendly and affordable!

Should I use 400-watt solar panels to power my home?

The short answer is – yes!

You can wire together several 400-watt panels to build the solar system size you need.

For instance, a typical 6 kW home solar system will run you about fifteen 400 W panels for your roof. Several front runners in the solar manufacturing industry (like the ones we listed above!) offer panels in the 400s range for home or commercial use. 

Panels nowadays do have higher wattage, but that doesn’t mean 400-watt panels are a thing of the past. In fact, they’re a good choice to make the most of your roof space. Not to mention, they’ve also become a relatively affordable option.

Final thoughts: Are 400-watt panels right for you?

400 W solar panels are an excellent choice for running your home or business. In fact, they’re now very common, especially for residential solar panel installations. Because solar panels are so much more powerful now than before, you can install fewer panels while still covering all of your energy needs.

Make sure to get 400-watt solar panels from a trusted solar company that carries reliable panel brands.  Your solar installer can help you decide the best 400 W panels for your home and design a system that gives you the best solar panel savings possible!

How much can 400 W solar panels save you?
 - Author of Solar Reviews

Jamie Smith

Content Writer

Jamie is a Content Writer and researcher at SolarReviews. A recent graduate of La Salle University in Philadelphia, Jamie earned her B.S. in communications with a concentration in journalism, mass media, and public relations.

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