What is the Average Size of a Solar Panel?
Solar Energy is arguably the most versatile of all energy sources. There are one-inch solar strips powering calculators, and there are hundreds of acres of a solar plant powering several towns. It can be used for any size of application. Naturally, it is neither easy nor wise to manufacture a single panel covering an entire rooftop or several acres of land. Thus, the need for the manufacturing of panels in the sizes that we have.
The size of an average solar panel is dependent on the number of cells encapsulated in it and the panels’ application. Understanding panel sizes (and weights) can be important from the point of view of selecting sizes based on roof-space and the customer type (residential/commercial).
The Difference Between Residential and Commercial Solar Panels
Although the underlying technology and system structure is pretty much the same everywhere, the panel sizes may vary based on available space of installation. Residential systems, typically rooftop systems, usually require a few hundred square feet. They also require due consideration to the roof’s ability to carry weight.
As such, residential systems usually employ slightly smaller panels as compared to a commercial system. Usually that is 65 inches by 39 inches, or 5.4 feet by 3.25 feet. Speaking of commercial systems that have a comparatively much larger number of panels, the size is normally 77 by 39 inches, or 6.4 feet by 3.25 feet. The depth of a solar panel may be anywhere between 1 and 2 inches, and depends mainly on the frame thickness.
You may have noticed that in both the cases, the width remains same. This factor is governed by the way solar cells are placed inside of a panel. Generally, there are six columns of cells, for both cases. For the smaller panels, there are 10 rows along the length, making 60 cells in one panel. For the larger one, there are 12 rows, making it 72 cells per panel.
(Image source – Sunmetrix)
When going for rooftop systems, an important thing to consider is the weight of solar panel. With all of the glass, frame, and laminating sheets contributing, the average weight of a solar panel is 40-50 pounds depending on size. Alternatively, it can be also said that panels weigh 2-4 pounds per square foot.
Besides the length and width, the word ‘size’ may mean different things to different people. Especially for people working in the solar industry, panel size usually refers to the maximum power a panel can generate. This is measured in Wp (Watt peak – Watts generated in standard or ideal conditions). For instance, a 77 x 39 panel may have a power rating of 320 Wp.
How Do Physical Size and Power Rating Relate?
Though both are spoken in different numbers, the physical size does control the power rating. This depends totally on the power generating capacity of individual cells. PV cells come in the power ratings of 4 to 5 watts. A high efficiency cell with 5Wp rating used for a 72-cell panel will give us a 5*72 = 360Wp panel. The same cells for a smaller sized (60 cell) panel would mean a 5*60 = 300Wp panel.
In a remarkably short duration, the energy produced per cell has been steeply increased. Solar cells are becoming more and more efficient. Consequently, as time progresses, solar panels will continue to get smaller for the power they generate, and they will require less space on roofs or the ground.
Knowing How Many Solar Panels Can Fit on Your Roof
Residential, rooftop solar systems are slowly becoming more and more popular. The technologies are advancing rapidly, including installation systems. With a host of available types, roof mountings are safer and they don’t damage the roof in any way, if done the right way.
In the design of any such system, an essential criterion is the available space. Besides, as far as energy consumption is concerned, a ‘one-size fits all’ approach never works. Thus, the other essential criterion is the energy consumption. Local solar panel installers in your vicinity can always calculate a system size and provide a quotation, but it certainly helps to know how to calculate the amount of solar panels you need yourself.
From the numbers in the previous sections, you can calculate the area of a single solar panel. Dividing your roof area by a single panel’s area will give you an approximate number of solar panels that can fit on your roof.
For example, a 60-cell panel will be about 17.5 square feet large. Assuming you have a 1500 square feet roof, that would mean you can ideally install 1500/17.5 = 85 panels. However, there can be shaded areas on the roof where the panels won’t perform well, and should be avoided.
As mentioned earlier, it is also important to know the required size in terms of energy consumption. The average system size in the United States is 6kW, and assuming a single panel is of 300Wp, one would need 6000/300 = 50 such panels for an average house.
Thus, we can see that area-wise the maximum number of panels ‘that can fit’ can be larger than the actual number of panels ‘required’ based on the energy utilized.
Finally, we can summarize saying that the size is controlled by the number of cells on the production side and by customer type on the installation side. It continues to get smaller though, and the future will see high efficiency panels that don’t eat up a lot of space.