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400w Solar Panels: What You Need to Know

400w Solar Panels: Benefits, Cost, Installations and More

Key Details

  • To power an average sized home, you'll need fifteen to twenty 400-watt solar panels
  • A single 400-watt panel can run a small fridge and charge laptops and other low energy consuming devices.
  • It takes 3 to 4 hours for 400 watts solar to charge a 12v 100ah battery.
  • 400-watt solar panels are more efficient at capturing solar energy, compared to lower watt options

Installing 400w Solar panels

How Much Power Will a 400w Solar Panel Produce?

A 400-watt solar panel has enough wattage to power small-scale devices, such as TVs and electric lights, in residential or commercial settings. On average, it'll generate between 1 and 3 kWh daily. Keep in mind that the output depends on factors such as peak sunlight hours.

To calculate the number of solar panels for your home, you'll need to determine your annual electricity usage.

Besides the 400-watt panel, there are other types of panels based on their watt output. You'll often find 100-, 250- and 365-watt panels at most solar companies.

Why Choose 400W Solar Panels?

400w solar panels offer several benefits. Some of these include:

400w Solar Panels are more efficient at capturing solar energy.

Most 400-watt panels are either monocrystalline or PERC panels, which have an efficiency rating between 20% and 25%. This means they can receive and convert 25 percent of solar energy. If the sun emits 1,000 watts, then the panel can convert 250 watts into electricity.

A 400w Solar Panel Takes up Less space.

400s solar panels are a good pick for solar users living in compact spaces. That's because the higher the wattage, the fewer panels you need to install.

In addition, a 400-watt solar panel, such as a monocrystalline or PERC panel, can perform well in low-light environments.

Is a 400w Solar Panel Enough?

A singular 400-watt panel is strong enough to power devices with low energy consumption. This may include consumer devices like TVs, laptops, light bulbs, printers, fans, and even mini-fridges.

However, a single 400-watt solar panel is insufficient to power high-energy-consuming appliances like microwaves and dishwashers. For this reason, it's advisable to invest in multiple 400-watt panels to cover residential or commercial energy needs.

Experts advise that solar users also factor in future energy demands when installing panels.

How many 400w Solar Panels Do I Need to Power a Home?

You'll need to install fifteen to twenty 400-watt solar panels to power an average-sized home in the US.

To calculate the number of required solar panels, you must determine your annual electricity usage. Next, divide it by the production ration. Furthermore, divide your answer by the required solar panel wattage.

According to the Energy Information Administration, an average-sized household uses 10,632 kWh per year. Also, the average production ratio is 1.45 in the US.

10,632 divided by 1.45 = 7,332.

Next, 7,332 divided by 400 watts is 18 solar panels.

Number of 400-watt solar panels needed to power a home

Household Size Solar PV System Number of 400W solar panels
1 bedroom apartment 1 kWp 3
Two bedroom 2 kWp 5
Three Bedroom 2.5 to 3.5 kWp 8
Five Bedroom 5 13

Will a 400w Solar Panel Run a Fridge?

A 400-watt solar panel generates just enough power to operate an energy-conserving fridge. An energy-efficient fridge may require up to 200 watts to operate. However, fridges in this category are often small and insufficient for most residential or commercial uses.

An average-sized household will mostly invest in large refrigerators that consume between 400 and 600 watts. For this reason, it's better to invest in more than one 400-watt solar panel. Solar users may also consider batteries as backups for solar energy.

Can a 400-watt solar panel charge a laptop?

Yes. Laptops have a low energy requirement and may use between 15 and 60 watts. This means a single 400-watt solar panel generates more than enough electricity to power laptops. Nevertheless, solar panel output is not consistent and may depend on factors such as sunlight hours and the angle of the panel.

Charging Batteries with a 400w Solar Panel

How many Batteries do I Need for a 400-watt solar panel?

To get an accurate calculation, you must consider these factors:

  • Battery type and capacity
  • Peak sunlight hours

Peak sunlight hours

This is the period when solar panels receive the highest concentration of sunlight. Places like Arizona receive between 7 and 8 hours of peak sunlight daily, while Alaska gets only 2 to 3 hours of peak sunlight daily. So, a 100-watt panel in Arizona is expected to generate up to 700 watts in a day.

As a rule of thumb, your solar battery must hold at least twice the daily energy output of a solar panel. This means you'll need between a 100Ah and 150Ah battery for a 100-watt solar panel. You'll need even more for a 400w solar panel.

Battery type and usable capacity

Solar batteries come in different designs, including lithium-ion batteries, lead-acid batteries, and gel batteries.

Lithium-ion batteries are generally preferred for their longer lifespan, light weight, and usable capacity. However, they are more expensive than other alternatives. Lead-acid batteries are cheaper but less durable and require much more maintenance.

Furthermore, each battery type has a specific usable capacity. This is the amount of power you can access from a battery. A lithium-ion battery has an 85–100% discharge rate. Conversely, lead-acid batteries have a lower discharge rate of 50%.

Can a 400w Solar Panel Overcharge a Battery?

Yes. A solar panel will continue to supply electricity to the battery as long as it receives solar energy. This may result in overcharging, which may lead to energy loss in batteries.

To mitigate the risk of overcharging, solar users should invest in batteries with a charge controller setting. Most high-end batteries come with a charge detector that will either cut off excess power or emit high pitched sounds when it is full.

How Long Will a 400-watt Solar Panel Take to Charge a 12V Battery?

It depends on many variables, including the capacity (ah) of the battery. For a 12-volt, 200-ah battery, a 400-watt panel will charge it within 6 to 8 hours.

A 12-volt, 100Ah battery has a 1,200-watt capacity (12 volts x 100).

The charge rate is also another important criterion. Lithium-ion batteries have a faster charge rate than lead-acid batteries.

How long will a 400w solar panel take to charge a 100Ah battery?

It will take between 3 and 4 hours for a 400-watt panel to charge a 12-volt, 100Ah battery. Keep in mind that the charge rate may fluctuate depending on the number of sunlight hours and the battery type.

How Fast Can a 400w Solar Panel Charge an RV Battery?

It will take three to four hours for a 400-watt solar panel to charge a 12-volt, 100-ah RV battery. Most RVs have 12 volt batteries with a capacity between 100 and 125 ah.

Travel RVs may require a battery capacity of up to 400 Ah. So, it'll take up to 12 hours to charge a 400 Ah in travel RVs.

Top 400W Solar Panel Brands

Some of the top 400-watt solar panel brands include:

The HiKu Mono Perc

The HiKu Mono Perc series from Canadian Solar+ has one of the highest efficiency ratings at 20.6 - 21.6 percent. It uses a monocrystalline PERC-technology solar cell to deliver between 400 and 425 watts of power. It weighs 34.4 kg (75.8 lbs) and uses a tempered glass frame to protect the cells.


  • Efficiency rating of over 20%.
  • Strong aluminum and tempered glass build.
  • Has an output of over 400 watts in peak sunlight hours.

The Sunpower A400-G-AC Series

With over 400 watts of output, the Sunpower A400-G-AC Series is a powerhouse and an investment for residential solar users. Its features include integrated microinverters, a light build (less than 46.5 lbs (21.1 kg)), and a tempered glass surface with an anti-reflective coating. Most importantly, it has a 25-year warranty.


  • A lightweight yet durable build
  • high solar efficiency rating of 22.5 percent.
  • guaranteed performance over a 25-year lifespan.

LG Solar LG400N2W-A5

The LG Solar LG400N2W-A5 is a 400-watt monocrystalline panel with an efficiency rating of 19.1 percent. Each panel contains 72 cells, and each cell generates up to 5.56 watts. Furthermore, it is designed to retain 86 percent efficiency after a 25-year lifespan.


  • Generates up to 400 watts of power.
  • Retains an 86% efficiency rate after 25 years.

Mission Solar MSE 420SX6W

The MSE 420SX6W from Mission Solar is a 400-watt monocrystalline PERC panel with a 19.3% efficiency rating. It weighs approximately 49 lbs., and its dimensions are 82.12 x 41.49 x 1.57 in. Like other 400-watt panels, it has a 25-year lifespan.


  • Extremely affordable when compared to other 400-watt solar panels.
  • Lightweight and durable build
  • high efficiency rate.

Tallmax TSM-DE15M(II)

Produced by Trina Solar, the Tallmax TSM-DE15M (II) is a 144-cell monocrystalline panel. It has an output range between 350 and 415 watts in peak sunlight hours. Furthermore, it has a lightweight build and uses durable, heat-resistant glass to protect the solar cells.


  • Highly durable and resistant to acids, ammonia, salt, and sand.
  • Lightweight (22 kg) and easy to install.
  • Generates up to 415 watts.