Array Mounting Styles - Green Alternatives Inc.

Different types of panels have come across the market (thin film, monocrystalline, polycrystalline) regardless of your panel type they can typically be placed one of two places-on the roof or on the ground. Some experimenting has been done to place panels on building walls, or floating in ponds, but for most facilities roof and ground mounted arrays are the way to go.

Roof mounted arrays are often what is imagined when considering solar. But if it’s not an efficient placement option, you’ll have to look elsewhere. If your roof is shaded, facing the wrong direction, or too small or old it wouldn’t make sense to place panels on the roof. Choosing your array location is critical to the production you can expect. They should also be considered permanent. Don’t expect to place panels and take them off in 5 years to redo the roof for cheap, on average you will be spending 30% of the original project cost on removing and reinstalling. On the flip side, if you have a large, south facing, newer roof and little open ground, your roof could be the perfect spot for an array!

Obviously, there are many types of roof spaces and surfaces. Let’s take a quick look at a few options:

Flat, Membrane Roofs
These roof surfaces are ideal for a ballasted mounting system since you do not want to penetrate the roof surface to install. These are easy to install if obstacles on the roof are minimal. An engineering study is done to determine the amount of ballast needed at all the critical locations to secure the system. Pitch on these usually varies between 5 and 15 degrees.

Pitched, Shingled Roofs
If the pitch on a building is not too steep, above 6/12 pitch, asphalt shingle roofs can also be a great place for an array. Systems designed for these roof types include flashings to prevent any kind of water penetration into the building.

Metal Roofs
Metal roofs can be trickier to determine the appropriate connectors. Standing seam and trapezoidal roofs can use specialized clamps to secure an array to the roof. If you have a corrugated, external fastener style roof, however, penetration through the metal may be required.

Production of roof-mounted systems will be tied directly to the direction the array faces and the fixed pitch of the array.

Ground-mounted solar arrays are a quick favorite for installers and are ideal for many farm and commercial applications. You can locate them to the most optimal area of the property (low shade, southern facing, close to a utility meter) and design as large or small an array as budget and energy parameters allow. When using ground-mounted panels you can install bi-facial modules which have even greater productivity since they will absorb light from both front and back. Here again, there are a few options to consider:

Fixed Array
In this scenario, the array will be set to a fixed pitch throughout the year and so the production is not as optimized as an adjustable rack. However, production from a ground array is almost always higher than a roof array due to increased airflow around the system.

Adjustable Array
This type of system usually requires a manual adjustment in the pitch of the array at key times of the year. Usually, adjustments made in the spring and fall suffice to increase the production of a system by 5 to 7%. In the northern hemisphere, the array is set upright in the fall to optimize the winter sun angle and placed in a flatter position to catch the overhead angle of the summer sun.

Tracking Arrays
These are motorized arrays that will follow the sun from east to west throughout the day. This really optimizes the available sun every day of the year. However, this requires motors and moving parts which will need regular maintenance and could see failures from time to time.

A qualified installer can help you walk through all the options for your property and should be able to provide production estimates for any site you wish to explore.

Cindy Rohaly

VP & Director of Sales at Green Alternatives, Inc.

Cindy started as a consultant with Green Alternatives in 2009 and has moved into her current position within the last few years. She loves meeting with potential clients, answering their questions, and ultimately designing a PV solar system that meets their needs and goals.