Overview of Solar Panel Popularity
In this era of climate uncertainty, solar panels are making headway using free solar energy and renewable energy. In the United States, solar power makes up 116 million metric tons of carbon dioxide every year. That’s like planting two billion trees.
Enter residential solar panel systems. They’ve been around a long time, and their manufacture is only improving each passing year.
Many homeowners wonder how to save on energy bills. Many look to installing solar energy panels as a possible solution, especially if they live in areas with lots of sunlight.
But how much work is it to install them on your roof? What are the solar panel weights, and can your roof support the weight? What’s the typical solar panel size if you worry your roof is too small?
As you’d expect, there’s a lot of variation among solar panels. A lot depends on the brand, technology, materials, and particularly the latest manufacturing techniques, which seem to make things smaller and more compact each passing year.
What Are the Different Types of Rooftop Solar Systems?
Photovoltaic Panel System (PV Cells)
Typically, the average weight of a photovoltaic panel (also known as a thin-film panel) is 40 pounds but may range from 33 to 55 pounds.
However, more context is needed. What is the solar panel weight per square foot? This statistic may be more meaningful for you in figuring out if your roof can bear the weight of solar panels.
For residential photovoltaic panels, the typical weight distribution is four pounds per square foot, quite manageable for most residential roofs.
Monocrystalline Panel System
While more common in commercial settings, some residences do have them. While they are heavier than photovoltaic panels, typically weighing 50 pounds each, they generate very efficient and powerful energy (as expected for large-scale commercial needs).
Since they were among the first solar panels to be developed, they have a long history of innovation and hence are the most advanced inefficiency.
Over the years, the manufacturers of these panels have steadily lightened the load per square foot while at the same time generating more energy output.
Polycrystalline Panel System
The newest type of solar panel to hit the market, they benefit the most from advanced technology, starting with the newest concepts. However, they were modelled after the monocrystalline panels, attempting to duplicate their sheer power while being far cheaper to produce.
Today, they are still the cheapest type of solar panels produced, making them more affordable. In addition, its typical weight is 42 pounds, which puts them closer to the range of photovoltaic panels while being much cheaper.
One other advantage is that since this type of solar panel is heavily promoted, its manufacturers are making greater strides in energy output.
The Dimensions of Average Solar Panels
The dimensions, not just the weight, are important as well. First, it answers the question: will it fit on my roof? Second, it will also answer the question: what is the weight distribution per square foot?
Regardless of the type of solar panel technology, average solar panels usually come in two standard dimensions:
· 60-cell panels: 3.25 feet by 5.50 feet
· 72-cell panels: 3.25 feet by 6.42 feet
You see, the component solar cell is a 6 inch by 6-inch square. So the only difference between the two standard dimensions is that they’re arranged in different patterns.
The 60-cell panel system, it’s 6 solar cells wide and 10 solar cells long. The 72-cell panel system, it’s 6 cells wide by 12 cells long, making them about a foot longer. There are also smaller, more compact models that use fewer cells.
Calculating How Many Solar Panels You Need
The typical American household would require about 867 kWh of electricity per month. (kWh = kilowatts per hour)
To be clear, a kilowatt is a measurement of power, while a kilowatt-hour is an energy measurement. So, for example, if you use your 1,000-watt vacuum cleaner for one hour, you’ve used up to 1 kWh.
What’s interesting is that an energy-intensive device like a clothes dryer can reach 1 kWh in a short time, while a low-maintenance device like a television monitor can take a long time to reach 1 kWh.
Experts have calculated that a 6.5 kW solar array system (for example, the entire setup of all panels would generate 6.5 kW of power, with typical sunlight during the month) would meet this requirement of 867 kWh per month.
Remember, there’s a lot of variabilities, as we know too well from forecasting the weather! However, these ballpark numbers help us move forward on best practices.
Here’s the range of watt power for the two standard dimensions:
· 60-cell panels: 285 to 315 watts per panel
· 72-cell panels: 335 to 375 watts per panel
Without going into too many calculations, let’s say from experience that a typical solar system would use 18 to 23 panels to meet this 6.5 kW power requirement, which helps meet the stated 867 kWh energy need per month.
Let’s now look at two precise configurations using the two standard dimensions, both of which fall within the energy requirements as stated above.
Since the 72-cell panels are bigger, we would only need a set of 2 panels in rows by 9 panels in columns (18 panels in all). However, for the 60-cell panels, we would need a set of 8 panels by 3 panels (24 panels in all).
Remember, these are just suggestions. If your roof is more of a square in shape, for example, you could arrange the 72-cell panels by three rows and 6 columns instead, still meeting the total number of 18 panels.
Here’s the final computation of numbers answering your questions as to space and shape needs and to help you understand solar panel size:
· 2×9 72-cell panels: about 29 feet by 13 feet (without rounding off, 375.4 square feet)
· 3×8 60-cell panels: about 26 feet by 16.5 feet (429 square feet)
How Much Do Solar Panels Weigh?
As we’ve discussed, it’s the solar panel’s weight distribution, for example, four pounds per square foot. That means since the panels are flat, the weight is nicely spread out on the rooftop rather than exert undue pressure upon one point.
Most solar panels weigh between three to four pounds per square foot.
However, it would be necessary to know the total weight despite the distribution of weight, as your roof can only bear so much additional weight on the point loads. Going with a typical figure of 40 pounds per 60-cell panel, the 3×8 arrangement (total 24 panels) would weigh 960 pounds.
While that sounds like an enormous lot of weight, remember that they are very flat and spread out, and each panel weighs a manageable 40 pounds. It’s just that adding them all up at once piles on the weight fast, but it’s not a stack—it’s a layout.
The hardware and mounting hardware also slightly add weight to hold the panels in place, increasing the combined weight.
If you are not sure your roof can bear the weight of the solar panels, you can seek professionals like architects or structural engineers to evaluate your roof strength and its structural integrity.
You’d need to seek commercial installation if you own an office building, but several roofing companies offer both residential and commercial.
If the professional agrees the roof can safely bear the installation of the solar panels, they will give you a certificate of approval.
However, if the roof isn’t strong enough, they will give you recommendations on fortifying your roof. Possibilities include bracing the rafters or beams further or replacing some of the roof itself.
Roofing companies who do the solar panel installation can also offer an informal assessment of your roof’s strength, so you don’t have to incur the expensive fee of a higher-priced professional.
In general, most detached homes can support residential solar panels. You can check your local listings for solar installers, and they can advise you of the best solar panel system.
With their experience installing solar panels, they can also advise how much solar panels weigh and how much they cost. Finally, they’ll tell you how many watts you can get out of your new solar panels.
Will the Solar Panels Damage My Roof?
There are some special considerations for differing kinds of roofing materials.
1. Corrugated steel roofs. Those can use brackets as mounting equipment specifically designed for the wavy shapes of the corrugated steels and are widely available in hardware stores. The solar panels will not damage the rooftop when installed.
2. Asphalt shingles. The danger to the roof from installing the solar panels is from drilling holes in the roof, which increases the possibility of leaks if nothing further is done. It is best to put flashing around the drilled holes to prevent leaks.
3. Standing seam roofs. Typically you can use clamps to mount solar panels; such methods do not require drilling into the rooftop.
4. Flat roofs. Since such roofs are flat, there is not as much necessity to secure the solar panels since there is no angle. Instead, you would use ballast roof mounts, which are very easy since they involve using specially manufactured cement blocks that can secure solar panels once installed.
A common question is if mounting solar panels onto a roof will void a warranty by the roof manufacturer. Sometimes it would, especially for older warranties, but the solar panel company often gives you their own warranty, which should put concerns to rest.
If you have any older roof that needs replacement anyway, you can double your benefit by having the same roofing company install the new roof and the solar panels. In addition, they’ll give you many a pro tip on how to proceed.
Remember to check again with the structural engineer at roofing experts, and they’ll guide you with your brand new solar panels!