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Looking at 400 Watt solar panels: are they right for you?

Wattage is a confusing point whenever you choose solar panels. Homeowners prefer solar panels in the
300–350W range. Large commercial systems are made of 450W modules and higher. What about everything in the middle? In this article we’ll talk about 400W solar panels: features, usage and best models.

400W panels are slightly larger than normal home modules

The difference between panels for home and commercial systems is not only the power output but the size as well. Panels for residential systems usually have 60/120 cells and their size is around 39 × 66 inches. Panels that are over 430 W in power output usually have 72/144 cells and their size is approximately 39 × 77 inches.

400 Watt solar panels are right in between residential and commercial panels in terms of wattage and size. That’s why we often see 66/132 cell 400 W panels — for example, REC Alpha Pure Black or Q CELLS Q.Peak DUO. They are approximately
40 × 71 inches, but the size differs from model to model. This makes 400 Watt solar panels a flexible choice that fits all kinds of projects, except for solar farms.

Vasilii Smirnov
Solar Installation Expert

The division of panels for residential and commercial is somewhat conventional — you can put on your roof anything you want, as long as there is enough space for it. While larger modules can be harder to fit on a house roof, you can build a powerful system with less of them.

Get more power for less space

The average size of a home PV installation in the US is 5–6 kW. Let’s say, we have 20 panels 300W each. How much area do you need for a system like that? Let’s take the REC Twinpeak 2 panel as an example.

39.2 in × 65.9 in = 2583.28 sq in = 17.9 sq ft × 20 modules = 358 sq ft

Now we’ll build the same 6 kW system with 400 Watt solar panels. You would need 15 modules for it. Let’s take the Q CELLS Q.Peak panel that is 74 × 41.1 inches in size. 

74 in × 41.1 in = 3041.4 sq in = 21.12 sq ft × 15 modules = 316.8 sq ft

You can see that these two systems have the same power capacity. However, the second one needs 41.2 sq ft less. That’s enough room for two more 400 W solar panels, so you can scale up your system if you want to.

As you can see, using 400W panels will benefit you in terms of saving roof space overall. Being larger and a bit bulkier than standard 60/120 cell panels is basically the only downside. 400W panels are more expensive than less powerful modules, but you’ll need less of them, so the overall cost might be even slightly lower. These panels can also be a great choice for a mobile installation, such as RV or a boat system. Even a single 400W solar panel can sometimes be enough for everything that you’ve got. 

If there just isn’t enough room on your roof to build the right system for your needs, consider a ground-mounted solar system. It is cheaper to install and easier to adjust the positioning and tilt of your panels to maximize the production. The most significant downside is that it takes up space in your yard. Ground-mounted systems also get dirty quicker and you'll have to clean the panels more often.

Our favorite 400W panels:
Solar engineer recommends

Let’s bring forth a few 400 Watt solar panels that our engineer likes the most. Here’s our lineup:

REC Alpha Pure Black

One of the most efficient solar panels on the market, REC Alpha Pure Black shows 21.6% conversion rate. It comes with 25-year warranties for labor, output and product, if the installer is certified by REC. The panel is extremely durable and its half-cut cell design contributes to higher shading tolerance. It’s a bit costly, but overall it’s genuinely one of the best solar panels on the market.

Canadian Solar HiKuBlack

While this solar panel has 132 solar cells, it’s just as large as a 72/144-cell module:
76 x 41 inches in size. The model comes with 25-year warranties for product, performance and labor. It withstands snow loads up to 8100 Pa and wind loads up to 6000 Pa, so tornadoes and hurricanes aren’t a threat to it. Just as any other Canadian Solar panels, Hiku Black shows excellent performance in low-light conditions.


This 400 Watt solar panel from Korean-German brand Q CELLS shows high efficiency of 20.4%. It performs well in all kinds of weather, whether it’s hot or cloudy. The panel is protected from Potential Induced Degradation (PID) and hot spots development. 25-year warranties for product and performance are included.

Solaria PowerXT-400R-PM

American brand Solaria puts out on the market possibly the most beautiful solar panels that there are. PowerXT has a special design: it is made out of solar shingles instead of solar cells. As a result it has an unconventional size: 65 x 47 inches. Shingled solar panels from Solaria lose 40% less energy to shading than standard panels. PowerXT comes with a 25-year warranty.

Canadian Solar HiDM5 All Black

Another panel from Canadian brand, HIDM5 features all-black design which makes it look good on any roof. It provides strong and steady power output even on cloudy days. The panel comes with a 15-year warranty for product and materials and 25-year warranty for performance. It is relatively large: almost 80 inches in length and 39 inches wide.

Andrey Gorichenski
Senior Editor

Andrey had been a news editor and freelance writer for a number of medias before joining A1SolarStore team. Climate change and its impact on people's lives has always been among his interests and it partially explains his degree in Philosophy and Ethics.

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