Residential vs. Commercial Solar Panels: What’s the Difference?

When comparing different brands of solar panels, you will notice that some models are described as “residential”, while others are described as “commercial”. However, this is just a naming convention for different panel sizes, and both types are composed of the same building blocks: solar photovoltaic cells.

solar panels on a residential rooftop

via Berkshire Photovoltaic Services Inc

A residential solar panel will normally have 60 cells, while a commercial panel has 72 cells. 60-cell solar panels are preferred in home installations since they use roof space more efficiently thanks to their compact design.

On the other hand, 72-cell panels are preferred in commercial and industrial buildings with abundant roof area, where larger panels can be installed with ease. However, commercial panels will work just fine on some homes, and the same applies for residential panels used in commercial or industrial buildings.

As we discussed in a previous article, solar cells can be classified into monocrystalline or polycrystalline, depending on their material structure at the microscopic level.

  • Mono cells are made of single silicon crystals, as their name implies. They are characterized by their black color and higher efficiency.
  • Poly cells are made of multiple crystals, which merge together during the manufacturing process, when molten silicon is solidified. These cells are identified by their blue color.

A solar panel is simply an array of photovoltaic cells, which are wired together and protected by a durable housing. This basic construction is used for both residential and commercial solar panels, and the difference lies in the number of cells used in each design.

Since the solar cells are wired together, their voltage adds up. For example, if you have a 60-cell solar panel where each cell generates 0.5 V, the total voltage output of the panel will be 30 V.

What Is a Residential Solar Panel?

Residential solar panels are characterized by their compact design, which uses 60 cells arranged into 6 columns and 10 rows.

The exact dimensions and weight of each panel depend on the brand and model, but they are generally around 65-66 inches tall and 39-40 inches wide. This means a solar panel designed for residential use will cover around 18 square feet.

  • As a quick example, assume you want to install an 8-kW home solar system.
  • If your solar panels have a rated output of 370 W each, you need 22 to reach 8 kW. The exact capacity would be 8.14 kW in this case.
  • If each panel covers 18.33 square feet (66” x 40”), you need 404 sq.ft. for the entire array.

In this example, the exact layout will vary depending on roof dimensions and shading. For example, if the array has 2 rows of 11 panels, it will cover an area that is 132 inches tall and 440 inches wide (11 feet x 36.67 feet). However, you could also have 2 rows of 5 and 2 rows of 6 on different areas of your roof.

Solar manufacturers are constantly improving the design of their PV cells, and many products now use a half-cell design that boosts efficiency. As you might guess from their name, these solar cells are 50% smaller, but twice as many fit in each panel. Residential panels with this design have 120 half-cells instead of 60 traditional cells, but they have the same dimensions.

What Is a Commercial Solar Panel?

Commercial solar panels use 72 photovoltaic cells, arranged into 12 rows and 6 columns. This makes the module 20% taller than a residential product while having the same width.

In other words, commercial panels have a typical width of 39-40 inches just like residential panels, but their height increases to 78-79 inches. Again, these are typical sizes you will find, but the exact dimensions will depend on the manufacturer and model.

You can use commercial solar panels on a home, and they will work just fine, but first you must make sure the roof has suitable dimensions for them. Also, many solar installers are dedicated to a specific market segment, and they often prefer to work with a single module size.

Assuming the same type of photovoltaic cell, commercial panels produce 20% more power than residential panels. However, their weight and size also increase by around 20%, and they are more expensive. Assuming the same conversion efficiency, you’re getting the same electricity output per square foot with both options.

  • With 72-cell commercial solar panels, you can reach the required system wattage with less units. However, their larger size limits their use on many home roofs, and solar installers often prefer to work with the smaller 60-cell panels.
  • With 60-cell residential solar panels, installers have more flexibility when designing the layout of your system. They also fit in roof sections that cannot accommodate 72-cell modules. You will also find that most residential solar quotes use 60-cell panels, which means you have more options.

72-cell solar panels can save on racking costs when used in large commercial, industrial, or utility-scale installations. Since these solar panels are taller than their 60-cell counterparts, the spacing of the racking system can also be increased.

The savings are minimal on a residential system since you only avoid a few feet of total racking. However, when you must install thousands of solar panels on a large industrial roof, the amount of racking material saved by large modules is considerable.

The half-cell design is also used in many commercial solar panels, resulting in 144 half-cells instead of 72 traditional cells. Just like residential panels with this design, the number of cells is doubled, but they are 50% smaller and the panel size stays the same.

Commercial solar systems are also different in terms of wiring and their overall design. Solar panels are connected in much longer series, and their inverters are also larger. For example, a home solar system may have an inverter capacity below 10 kW, with the panels connected in two strings.

On the other hand, a large industrial system may have several inverters with a capacity of over 100 kW each, and multiple strings of solar panels per inverter.

66-Cell Solar Panels: An Intermediate Size

The 60-cell and 72-cell solar panel designs are the most popular in the industry. However, many manufacturers also offer 66-cell panels, and they are growing in popularity. As you might have guessed, these panels are intermediate in terms of wattage, size, and weight.

The 66 solar cells are arranged in 11 rows and 6 columns, and the panel height is around 71-72 inches, while keeping the typical width of 39-40 inches.

The following are some examples of 66-cell solar panels from leading brands:

As you can see, many of these solar panels have a rated power of over 400 watts, without being as large as the 72-cell commercial panels. They offer a middle ground between the compact design of the 60-cell residential panels, and the higher wattage of the 72-cell commercial panels. 66-cell solar panels are often described as “residential”, but all three product sizes use the same basic technology.

In the example presented above for 60-cell solar panels, 22 units with a power output of 370W each were used to reach 8.14 kW of capacity. With 66-cell solar panels having an output of 410W each, you would only need 20 to reach 8.20 kW.

  • If each solar panel is 72” tall and 40” wide, the total area covered by all 20 is 400 sq. ft.
  • When arranged in 2 rows, the 60-cell panels covered a vertical distance of 11 feet.
  • With these 66-cell panels, 2 rows would be covering a vertical distance of 12 feet, but the horizontal distance needed is reduced by 40 inches (3.33 feet).

Residential and Commercial Solar Panels: Buying Tips

Regardless of the solar panel size used for your system, here are some recommendations you should follow to achieve the best results:

  • Look for reliable brands with solid warranties.
  • Get a professional design and installation.

There are many solar panels on the market, and they look very similar – you can only get an idea of their quality by checking their brand and specifications. When purchasing solar panels from a reputable and reliable manufacturer, one of the main benefits is warranty coverage.

A 10–12-year product warranty has become an unofficial “standard” in the solar industry, but some brands are now offering a coverage of up to 25 years. With a solid warranty, solar panels become one of the safest investments available for homeowners since any defective units get replaced for free.

However, working with a qualified solar installer is equally important. You can purchase solar panels from a top brand, but you will not get the results you expect unless they are wired and installed correctly.

An unprofessional installation increases the risk of electrical faults or fire, and you will generally lose the product warranty. You will notice that solar panels manufacturers state this clearly in their warranty terms and conditions.

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