There are many types of solar panels varying in size depending on factors like solar panel efficiency, design, technology, and others. While the size for solar panels with the same cell count varies slightly, most 60 cells solar panels have size rounding the 39 in. x 66 in. and 72 cells solar panels have sizes of around 39 in. x 77 in., but panels with cell counts of 96, 120, and 144 may have different sizes.
If you want to learn more about the common sizes for solar panels and what are the best options, this article is for you. Here we explain why solar panels are made the size they are, explore standard sizes for photovoltaic (PV) modules, estimate the size for a solar system, and explore other sizes for less common solar panels in the market.
Why Do Solar Panels Have the Number of Solar Cells They Do?
Circuit design for solar panels is created to meet certain voltage requirements matching that of battery banks. Solar panels feature 0.5V solar cells soldered together in series, increasing the voltage output of the module to the desired level.
For Off-Grid Installations
PWM charge controllers were the norm in the past for an off grid solar system, requiring the voltage of solar panels to match that of battery banks. Classic solar panels had 36 cells soldered together in series to produce 18V solar panels, which were ideal for charging 12V battery banks, considering that batteries charge at higher voltages, and you had to factor in voltage drops due to the charge controller and weather.
The 72 cells solar panels were alternatively made by solar panel manufacturers to match the voltage of 24V battery banks, which are a better option than 12V battery banks. Since 72 cells solar panels include twice as many cells as 36 cells solar panels and twice the voltage, they can charge 24V battery banks at the right voltage accounting for voltage losses.
After the introduction of MPPT charge controllers, the only requirement was that the input voltage had to be higher than that of the battery bank, limiting the maximum voltage input by the specifications of the controller, and no longer having to exactly match the input voltage with that of the battery bank.
Standard Solar Panel Dimensions
There are many solar panels featuring 6 in. x 6 in. cells, and others featuring different sizes. In this section, we explain the different standard dimensions for solar panels in the industry.
60-cells solar panel featured 60 solar cells of 6 in. x 6 in. per cells in a 6 x 10 grid. Due to the space between cells and the frame, these solar panels feature dimensions close to 39 in. x 66 in. or around 3.25 ft. x 5.5 ft. These panels produce a nominal voltage of 30V and have a power output ranging from 270W to 300W.
72 cells solar panels add 12 more cells than 60-cells modules, in a 6 x 12 grid. These solar panels have dimensions rounding the 39 in. x 77 in. or around 3.25 ft. x 6.42 ft. due to the space between cells and frame. These PV modules feature a nominal voltage close to 36V and a power output ranging from 320W to 400W.
96-cells solar panels are the new trend in the solar industry, further reducing power losses by increasing the voltage and keeping the current the same. These solar panels feature a 7 x 12 grid resulting in a dimension close to 41 in. x 62 in. or around 3.45 ft. x 5.21 ft. The 96 cell PV module features a nominal voltage of 48V and a power output rounding the 500W.
120 and 144 cells solar panels are the Half-cut solar cell models of the 60 and 72 cell options. These PV modules have similar dimensions to the 60 and 72 cell solar panels, featuring twice as many cells of half the size (6 in x 3 in). The rated power is slightly superior to that of traditional cell count.
How Large Can The Average Solar Array Be?
The average US home consumes 893 kWh monthly. Considering the average 5 Peak Sun Hours (PSH) in the US and a derating factor of 70% attached to PV losses, it is possible to calculate the ideal size for a PV system for the demand of the average home by using the following formula:
The result of the calculation is a PV system with a generation capacity of 8.5 kWp. Calculating the size for this PV system in the different solar panels available, allows us to estimate how many PV modules the average solar array should have.
|Load / PV module||Number of modules / Cell count||Average rooftop space required by the array|
|8500Wp/270Wp||32 x 60-cell modules||572 sq. ft.|
|8500Wp/300Wp||29 x 60-cell modules||518 sq. ft.|
|8500Wp/320Wp||27 x 72-cell modules||563 sq. ft.|
|8500Wp/400Wp||22 x 72-cell modules||459 sq. ft.|
|8500Wp/500Wp||17 x 96-cell modules||305 sq. ft.|
Performing an 8.5 kWp solar panel installation requires a rooftop space going from a little more than 300 sq. ft. to a little less than 600 sq. ft., but this is only an estimate. Since manufacturers may have different dimensions for their solar panels due to manufacturing variations, the overall size could vary depending on the type of PV module that you choose and the manufacturer.
How Big Are Portable / RV Solar Panels?
Standard size solar panels are not the only available options in the market. There are also mobile and portable solar panel applications. You can find electronics like a solar powered security camera featuring 30 – 40W 1.65 sq. ft. solar panels, portable solar chargers with smaller modules, and more.
RV solar panel kits and marine solar panels are other types of small PV modules featuring 100W, 50W, and even smaller flexible solar panels designed to power small appliances during your adventures. The 100W average flexible module has dimensions close to the 43 in. x 20 in., 50W modules have dimensions rounding the 42 in. x 11 in., while 35W modules have an approximate size of 23 in. x 13 in.
How Many Solar Panels Can I Fit on My Roof?
The average size for a home in the US has increased from 1,500 in the past to around 2,300 sq. ft. with 1,500 sq. ft. for the roof. Regularly, you cannot install PV modules all over the roof due to electrical and structural limitations, but this can give us an estimate as to the potential of using the whole roof for a home for a solar system.
Considering 72-cells 350W PV modules with dimensions of 3.25 ft. x 6.42 ft. (20.86 sq. ft.), the whole 1,500 sq. ft. area could fit a PV system of around 70 PV modules, which would roughly translate into a PV system with a generation capacity of 25kWp (if all area could be used).
However, PV systems this size are not usually feasible since many times roofs have obstructions due to the shape of the roof face, chimneys, skylights, vents, fire setbacks, shading and other factors, that highly limit the number of panels that can be installed. Also, some areas of the roof may not be usable for solar panels because of limited dimensions that would not be able to fit a single panel properly as can be seen in figure 7. Real case scenarios mostly would fit systems anywhere between 7 to 10kW.
Conclusion: Choosing the right PV module size for you
Choosing the right PV module includes several factors like cost, desired power output, and many other factors, but it is always important to consider the available space to fit the modules for your installation. With the information in this article, you will be able to consider the different sizes for PV modules and will be able to calculate the required space for your desired PV system.
While the number of PV modules will be always limited by the input of your solar power inverter, we also consider additional important aspects like the obstructions on the roof and fire setbacks required in some jurisdictions. Taking all of these into consideration alongside the size of the PV modules will allow you to select the best solar system at your home.
Frequently Asked Questions (F.A.Q.)
When learning how do solar panels work, one of the first aspects we learn about is efficiency, which is the main reason for having two solar panels with different dimensions, even though they have the same power peak value. Smaller PV modules designed with a technology that highly increases their efficiency will produce the same power rate with a much smaller size.
The size of a solar panel is usually linked to the number of solar cells installed and its rated power. Bigger solar panels designed with modern technologies will naturally cost more than smaller options.
Rigid solar panels had higher efficiencies and a lower cost in the past, making them better suitable to install on rooftops. However, thin-film technologies now have higher efficiencies, which is why they are starting to manufacture these modules in larger sizes than used to be done only for traditional PV systems. Nevertheless, thin-film panels still do not have the same size as traditional ones.
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