Metal Roofs Have a Solar Advantage
When it comes to harnessing the sun’s free energy, metal roofs have a solar advantage that makes them an excellent option if you want to add solar panels to your roof. Here, our experts at Kauffman Roofing in Jamesport discuss the advantages metal roofs offer for solar energy. Of course, we can also help you decide whether a metal roof is the best one for you or if another type is a better fit for your needs.
Many rooftops across the United States have solar energy collectors that turn sunshine into electricity. These have photovoltaic (PV) panels or solar panels that help flat or southern-facing roofs generate electricity. Solar panels can save you money on energy consumption and help reduce emissions of CO2 and pollutants by taking the place of the burning of fossil fuels.
Currently, the United States is the third-largest solar market in the world and may soon become the second? The amount of solar power installed in the U.S. has increased more than 23 times over the past eight years. According to the Solar Energy Industries Association, that’s enough energy to power over 5 million average American homes.
The Department of Energy sees this increase as the result of pricing for solar energy continuing to fall, making it a more popular, even economical energy choice for American homeowners and businesses.
A Building Design + Construction Network article discusses the powerful and untapped energy of the sun, explaining how sunshine averaged over the earth, is about ¾ of a kWh per square foot per day. But when there’s bright sunshine at the ground level, it’s about 100 watts per square foot during the sunniest times of the day. So, a roof with 1,000 square feet can get up to 100 kW to 750 kWh of energy during the sunniest times of the day.
For those who want to tap into this power by installing solar panels, metal roofs have a solar advantage. According to the article, metal roofs have an installation advantage, a longer life expectancy, and offer what’s known as cool roofing. Let’s take a look at each of these.
Silicon solar cells need protection from an aluminum and glass encasement because they can be easily broken and have fragile wiring connecting them. They need solid support, so a racking system is typically needed for most roof installs. These are anchored by drilling into the roof, which can mean a potential leak. Strong wind can also pull at the fasteners and widen the roof holes.
However, mounting panels to a flat seam, metal roof is a better option. They can be clamped directly to the standing seams of the roof, eliminating any penetrations, as well as the need for a racking system.
Did you know metal roofs can last 60 years or more? Their longevity fits nicely with the service life of solar panels. The warranted life of today’s solar panels is 20-25 years although many last much longer. Most non-metal roofs don’t last that long. So that means when you need a new roof you will have to take the solar panels down, replace the roof, and then re-install the solar panels.
But if you have a metal roof and it’s properly maintained, you will not have to remove the solar panels until their service life is over. That will save you the expense and power disruption inherent with other roof types. A metal roof also makes it easier to replace the solar panels with newer, higher-efficiency solar collectors of the future.
Another reason why metal roofs have a solar advantage is the frequent use of reflective coatings, often called cool roofing. This reduces the roof’s surface temperature, which then improves the performance of the photovoltaic (PV) modules.
This happens because the PV modules can get very hot in the sun, increasing the electrical resistance of the circuit they are powering and reducing total efficiency. If you use cool roofing, this negative effect is reduced and your solar cells are more efficient.
Next Steps for Adding Solar
So you’ve decided you want solar power and a metal roof. Your next decision is to decide which PV panels will be the best for your building. You can choose either crystalline or thin-film PV panels.
Crystalline silicon is more efficient but must be mounted in a frame because of their fragility. Glass panels are rigid frameworks.
- Monocrystalline panels are arrays of single slices of silicon crystal and are more expensive. They have a pattern of dark-blue, almost black squares with clipped corners, which are spaced very close together. Monocrystalline cells have up to 23% efficiency but cost more.
- Polycrystalline panels are made of fragments of silicon crystal slices which are combined into a flat surface. They usually look like blue squares or rectangles. Polycrystalline panel efficiency reaches 15%-18%.
Both the monocrystalline and the polycrystalline are embedded with strips of silver leads which are electrical contacts, like current collectors for the crystals. But they tend to block the sun and have a negative impact on efficiency.
Thin-film modules can be mounted on flexible substrates. They are encased in a frame but can be installed directly onto a roof. Thin film weighs about 75% less than glass panels but is usually less efficient than crystalline panels except in some low-light conditions.
What to Expect with Solar
As you’ve probably seen on other buildings, solar panels can take up most of the roof. Let’s say you use 75% of your roof and generate 10 watts/square foot on a clear day (10% efficiency modules). So, that means a 2,000 square foot roof can produce 15,000 watts (15kW) of electricity (2000 x .75 x 10w/sf).
Of course, this will depend on the weather and your location. Solar panels in the northern United States will generate less energy than in the southern part of our country because of the sun’s angle.
As you can see, metal roofs have a solar advantage in harnessing the sun’s energy. So talk to our experts at Kauffman Roofing in Jamesport, and we’ll help you decide whether or not a metal roof will work best for your building. We also specialize in repairs, preventative maintenance, and roof replacement, so let us know how we can meet all of your roofing needs. Call or contact us today.