By Tim Henderson
If you’re considering installing a residential solar power system, you’re likely planning to put the system on your roof. While ground-mounted solar panels are an excellent option, not many people have enough extra space to install a system in their yard. Because of this, roof-mounted panels remain popular. If you’re going to invest in a roof-mounted system, though, you need to be sure you have the right roof to sustain it.
How do you know if yours fits the bill? Here’s a helpful guide.
One of the first questions people ask as they consider installing solar panels is, “Is my house good for solar?” Fortunately, most roofs can sustain a residential solar power system.
Below are a few of the top factors that work together to make your roof compatible with solar power:
Which way do solar panels face? Orientation, or the direction your roof faces, may have a large impact on how productive roof-mounted solar panels will be. In North America, the best direction for solar panels to face is true South.
While it’s entirely possible to get excellent solar results without a south-facing roof, your system will generate the most energy when it gets as many hours of light exposure per day as possible.
Wondering what to do if you have a roof that doesn’t face true south? You’ll be glad to know it’s not as limiting as you may imagine. Many roofs face east or west, and most only lose about 10-20 percent of their energy generation capabilities. If your roof’s orientation isn’t optimal, speak with a qualified solar installer about your options.
Next, you’ll need to consider pitch. The slope or “pitch” of your roof influences your solar arrangement. While pitch is not as important as orientation, it can affect your system’s energy production capabilities. But what is the best roof pitch for solar panels? In most places, the ideal power generation angle is 30-40 degrees.
If your roof is too steep, it makes installation difficult and limits the ability of your panels to perform to their highest potential. If you’re installing solar panels on a flat roof, on the other hand, you’ll need to add additional racking to lift the panels to the right angle.
While solar panels have become more advanced in recent years, the age of your roof still has a great deal to do with how efficiently your system performs. Today, asphalt shingle roofs last about 20 years, while materials like slate or metal can last forty years or longer.
With this in mind, don’t install a new solar system on a roof that will need to be replaced shortly. Instead, replace the roof first and install the solar panels once the job is done.
While solar panels work in the shade and on cloudy days, they work better in direct sunlight. The “ideal” roof for solar gets ample sun and is only shaded during a short portion of the day.
Fortunately, solar power systems are adaptable. Even if your roof doesn’t get optimal sun, a qualified solar installer will likely be able to help you find a creative solution. Often, trimming branches or removing trees around the roof is enough to allow more sun to reach your panels.
What’s the best roof material for solar panels? Although rooftop solar arrays work with many materials, some are more “solar-friendly” than others. While most roofing products are generally suitable for solar, composite shingles are clearly the best and easiest for solar installation. Flashing and mounting panels on this material is usually quite simple.
Now, If you’re looking to install on wood shake shingles or clay, slate and terra cotta tile roofs, you may find it difficult to find a solar professional willing to take on such a job. These materials are extremely brittle, break very easily and is why most installers shy away from these roof types. What we generally recommend as a solution is to remove the tiles or shingles directly under the array and replace them with composite, since they’ll be hid under the installed panels anyway.
The size of your roof has a direct impact on the solar array you will purchase. According to SEIA, most residential solar panel systems are 5 kilowatts, which is about 20 250-watt panels. As a general rule, each kW of your system requires at least 100 square feet of roof space. Even if you have a large roof, keep in mind that elements like skylights and broken roof lines will limit your usable space.
Evaluating the suitability of your roof for solar panels is a critical first step – and our team can guide you through the process. After more than 13 successful years, Sandbar Solar is the most established solar company in Santa Cruz. Our solar panel installation projects reduce your energy bill and increase your property’s value. Installing solar panels for your home or business is also a green solution that helps preserve our planet.
If you’re interested in a residential solar panel system, contact our Santa Cruz solar experts for free estimates, custom design, expert installation, and more!
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Tim has worked in the solar industry since 2008. He has a Master's Degree in Energy Resources Engineering from Stanford University. His years of experience include working on solar energy projects for both homes and commercial properties. Tim enjoys sharing his knowledge of this evolving industry and making a difference in his community.
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