400-watt solar panels: Are they right for you?

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400 W solar panels.

One important metric to consider when comparing solar panel options is a panel's power rating, referred to as wattage. 400-watt (W) solar panels are above the average wattage of solar panels available today and can be a solid panel option for many types of solar projects.

Most solar panels installed in homes or businesses today are between 250 to 365 watts per panel. Solar panels above and below that range are also available. To determine if 400W solar panels are right for you, it is important to understand the options and how much energy 400W panels produce.

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A 400 W solar panel produces an output of 400 watts of electricity, which can be used for commercial and residential solar projects. 400W solar panels will produce approximately 1.2 and 3 kilowatt hours (kWh) daily, depending on their exposure to sunlight and other factors, including geographic location and tilt.

Because of their larger size and output, 400 W solar panels are 5-10%  more expensive than their smaller counterparts. They're generally more expensive in terms of cost per watt and overall. The technology used to produce this panel type is still relatively new. However, their larger size means you won't have to install as many of these size panels as smaller ones.

400 W solar panels are some of the largest panels on the market and are still relatively uncommon for use in residential applications. Most residential solar systems use 300 W solar panels. However, there are still many uses for consumers to try 400 W panels.

400-watt solar panels for boats and RVs

Although they are still not widely used for residential homes. 400 W panels are well-suited for powering RVs, boats, and other devices with off-the-grid use. A single 400 W panel could power an RV or boat for a significant amount of time.

Not many companies manufacture truly 400 W solar panels. Below is a selection of solar panels that produce close to 400 W of power, each listed with their efficiency and the company that makes them.

List of ~400-watt solar panels

Panel Model
Wattage (W)
Panel Efficiency (%)
Hanwha Q CELLSQ.PEAK DUO L-G5.2 38038018.9
Hanwha Q CELLSQ.PEAK DUO L-G5.2 38538519.1
Hanwha Q CELLSQ.PEAK DUO L-G5.2 39039019.4

The number of solar panels you'll install depends on the electricity you want to generate and the space available for solar panels. Many people choose to use the 400 W solar panel due to a lack of roof space because 400 W solar panels produce electricity more efficiently than many lower-wattage solar panels, given the space they take up. The table below compares different-sized solar panel systems by the number of 400 W solar panels needed for each system size. In some cases, the number of 400W panels is rounded to the nearest panel.

How many 400-watt solar panels do you need? System size comparison table

System Size (k W)
Number Of 400-watt Solar Panels
Estimated Space Needed (sq. Ft.)
2 kW5114
5 kW13296
6 kW15341
7 kW18410

*Number of panels rounded to the nearest panel, and space needed rounded to the nearest foot

Using five 400 W solar panels will produce roughly 3,000 kilowatts hours (kWh) of electricity, which is significantly below the amount of electricity a typical single-family household uses. Installing 15 panels for a roughly 6 kW system will produce enough electricity to offset your electric bill.

How much space will a solar energy system using 400 W panels take on your roof or property?

The table below demonstrates estimates for solar energy systems using only 400 W solar panels. To calculate the estimated space needed, we assumed that 400 W solar panels are, on average, 22.75 square feet (6.5' by 3.5').

System Size (k W)
Average Annual K Wh Production
Number Of 400W Solar Panels (rounded)
2 kW2,8205
5 kW7,05013
6 kW8,46015
7 kW9,87018

*Number of panels needed, rounded to the nearest panel and assumes a production ratio of 1.41

Solar panels close to 400 W are relatively efficient with the space they use compared to lower wattage panels, and a standard roof of a single-family home will likely have enough room for the number of panels needed to offset electricity costs significantly. Consider a ground-mounted solar system if you have a small roof or even a roof you don't want to be covered in panels.

400 W solar panels are above the average wattage of panels used for most solar installations but still will make sense for some property owners. While they may be more expensive per panel than lower wattage options, 400 W panels make up for the price premium in the space they save on your roof and the lower number of panels you will need to purchase to cover your electricity needs.

Whether you're looking for low, standard, or high-wattage panels, you can get multiple solar quotes from pre-screened installers by signing up on the EnergySage Solar Marketplace. If you have preferences regarding solar equipment, you can note them in your account so installers can quote accordingly. If you'd prefer to start investigating your solar options with a quick estimate on what solar can save you, try our Solar Calculator.

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