PV Rack Innovations: Page 2 of 3

Intermediate

Inside this Article

Eric Hansen of True South Solar
Eric Hansen of True South Solar fastens PV modules to a PV rack that includes a channel for keeping wiring tidy.
Unirac’s (E)volution Rack
Unirac’s new (E)volution rack, with I-beam rail and bonding-integrated mounting hardware, was designed to increase installation speed.
SnapNrack pitched-roof mounting system.
SnapNrack pitched-roof mounting systems have integrated wire management channels and flashing-integrated roof mounts. End clips fit under the module, so rails can be flush with the end of the module.
SnapNrack pitched-roof mounting system.
SnapNrack pitched-roof mounting systems have integrated wire management channels and flashing-integrated roof mounts. End clips fit under the module, so rails can be flush with the end of the module.
Schletter Gator mount.
Schletter’s Gator mount for composition roofs uses a flashing-integrated mounting block, which attaches via a single hanger bolt to the roof structure and the Gator Clamp solar rail attachment.
Quick Mount PV’s Quick Hook tile mount.
Quick Mount PV’s new Quick Hook tile mount is the first commercially available flashed tile hook mount.
Silicon Energy’s Cascade modules.
Silicon Energy’s Cascade modules are framed only along the long edges and attach directly to mounting feet rather than rails.
Zep Solar’s railless mounting system.
Zep Solar’s railless mounting system uses grooved modules and proprietary attachments.
Frameless Lumos Solar modules.
Frameless Lumos Solar modules are mounted on rails via hardware attached directly through the module, rather than to a metal module frame.
PanelClaw Polar Bear
PanelClaw’s Polar Bear is a ballasted low-slope roof solution that incorporates recycled rubber pads under the ballast trays.
Ecolibrium Solar’s Ecofoot2
Ecolibrium Solar’s Ecofoot2 is a ballasted system made of recycled plastic.
Renusol CS60
Renusol’s CS60 heavy-duty plastic ballast trays don’t need equipment grounding.
SunLink Core RMS
SunLink Core RMS is a low-slope roof rack solution that can combine mechanical attachment points with ballast weight.
DPW Solar’s top-of-pole mounts.
DPW Solar’s top-of-pole mounts, set at a low tilt for high summer production.
DPW Solar’s Multi-Pole mount.
DPW Solar’s Multi-Pole mount can be installed at tilts up to 55° and heights up to 14 feet above the ground.
Solar awning structure.
Silicon Energy Cascade modules incorporated in an awning structure.
Engineered carport canopy.
Left: Lumos Solar’s LSX engineered carport canopy.
Terrafix Solarpark earth screw
The Terrafix Solarpark earth screw is a fast foundation solution for large ground-mounted arrays. Using no concrete, they are easy to both install and remove.
SunLink’s ballasted ground-mounted rack.
Because it requires no ground penetration, SunLink’s ballasted ground-mounted rack is ideal for use where soil cannot be disturbed, such as at brownfield or landfill sites.
Eric Hansen of True South Solar
Unirac’s (E)volution Rack
SnapNrack pitched-roof mounting system.
SnapNrack pitched-roof mounting system.
Schletter Gator mount.
Quick Mount PV’s Quick Hook tile mount.
Silicon Energy’s Cascade modules.
Zep Solar’s railless mounting system.
Frameless Lumos Solar modules.
PanelClaw Polar Bear
Ecolibrium Solar’s Ecofoot2
Renusol CS60
SunLink Core RMS
DPW Solar’s top-of-pole mounts.
DPW Solar’s Multi-Pole mount.
Solar awning structure.
Engineered carport canopy.
Terrafix Solarpark earth screw
SunLink’s ballasted ground-mounted rack.

Beyond Rails

The mounting rails add cost in raw materials, shipping, embodied energy, and installation labor. Zep Solar, Westinghouse Solar, and Silicon Energy offer rack systems without aluminum rails. Instead, these use PV modules with special frames that connect directly to structural attachment points. Zep Solar and Westinghouse Solar have partnered with module manufacturers to add proprietary grooved frames—providing connection points that lock onto mounting attachments. Zep systems are designed so that microinverters or DC converters can be included. Westinghouse provides an AC module option. Silicon Energy’s Cascade modules are also designed to bolt directly to mounting feet and adjacent modules. They are framed only on the two long edges. Since there isn’t a frame and lip on the modules’ lower edges, water and dirt are more easily shed. 

Ballasted Systems for Low-Slope Roofs 

Low-slope roofs are often associated with large commercial buildings, but in many parts of the country, particularly the Southwest, they are common on residences. Because of the rapid growth in commercial installations over the past few years, the choices for low-slope rack systems have expanded dramatically and can be either ballasted or mechanically attached to the roof. 

Ballasted systems use rack and module weight, with additional mass like concrete blocks, to hold down the array and withstand wind uplift. Ballasted arrays frequently have no mechanical attachment to, and thus no penetration through, the roof. The building structure and roofing must be able to handle the additional weight, and the roofing installer and manufacturer should be consulted to ensure that a ballasted system won’t void the roof warranty.

Some new ballasted systems are transitioning from the standard aluminum and steel ballast tray components to heavy-duty plastic, which is nonconductive and doesn’t need to be grounded. Renusol’s CS60 is made from 100% recycled polyethylene. Each PV module is mounted directly on a Renusol base, at a set 10º or 15º tilt. Sollega’s InstaRack is also made from partially recycled polyethylene, and Ecolibrium Solar’s Ecofoot offers another ballasted mounting solution made of a 100% recycled content polymer plastic.

Mechanically attached low-slope roof racks have several roof-penetrating structural attachment points. This, in combination with the rack’s weight and design, ensures the modules can resist uplift forces. PV systems on low-slope roofs in seismically active areas usually require mechanically attached racks. Arrays with steeper tilts experience higher wind loading and may require more ballast. Less ballast may be needed if a combination of mechanical attachments and ballast is used. Nearly every major rack manufacturer has a solution for low-slope roofs, but a few, like PanelClaw’s Polar Bear and SunLink’s RMS, have focused very specifically on this application.

Pole-Mounts, Carports & Awnings

Ground- and pole-mounted PV racks commonly rely on a combination of steel and aluminum support structures—most often using steel poles supporting aluminum rails, although all-steel galvanized racks are becoming common (see “Ground Mounts for PV Arrays” in HP139). 

Pole-Mount Racks

The most common top-of-pole mount uses 4- to 8-inch steel poles embedded in a poured concrete foundation to support standard racks and rails. While pole mounts keep modules cooler, providing plenty of airflow around the array, there is a lot of excavation and concrete work needed to provide wind-loading support. The higher the array is mounted, the longer the buried pole needs to be. 

DPW Solar’s Multi-Pole mount uses 3-inch-diameter (or larger) steel poles to support a column of up to four modules in landscape orientation. 4- by 4-inch (or 5- by 4-inch) steel box tube, set horizontally, supports the module rails. The Multi-Pole mount can be adjusted from horizontal to 55º, making it a flexible solution that can be adapted to various array sizes. 

Carports & Awnings

With electric cars entering the mainstream market, more systems are being installed on carports. Lumos Solar’s LSX freestanding two-car canopy comes in a 5,760 W engineered package, featuring frameless glass-on-glass modules that allow some light through the array. Silicon Energy’s Cascade Series module is another double-glass, transparent module that can be installed in carport and awning structures for dappled sunlight.

General Motors, maker of the Chevy Volt electric vehicle (EV), has partnered with Sunlogics to make the Green Zone, a four- or eight-stall solar parking canopy and EV-charging station. SunPartner is another manufacturer of solar carports, offering a steel-supported 2,300 W single-stall model and a two-car, 4,600 W model, with array tilts from horizontal to 15°. Schletter makes custom carports, and their structures have even been used for solar-double cropping—for farms growing crops under and between rows of PV cover (see “Solar Double-Cropping” in HP147). DPW Solar’s Multi-Pole mount has been installed with the bottom module edge as high as 14 feet above the ground, making it another option for a solar carport or patio cover, and DPW offers custom-designed awning mounts as well.

Comments (7)

martin sattler_2's picture

Is there any way to figure out which Issue this article appeared in?

Scott Russell's picture

Sure thing, Martin. In the page header, just below the author's name, click on the blue "Issue date" link to display the issue in which this article was published. October/November 2012 in this case.

spriyanaren's picture

Good Article, but lack in step by step installation photos which will be very useful for entry level hobbyist & Enterprenur

Ben Root's picture

Michael is right, but look into other Home Power article like:
http://www.homepower.com/articles/p...
http://www.homepower.com/articles/p...
http://www.homepower.com/articles/l...
http://www.homepower.com/articles/r...
And others. Put " PV Racking" into the article search.

Michael Welch's picture

Hi there. Thanks for the feedback, it is appreciated. There are so many different rack solutions, so many different ways to put them on a roof, and so many different roofs; that it would be very difficult to do step by step instructions that would apply. One could write a book on the subject, but then the innovations are coming fast enough to quickly make the book outdated.

However, many rack manufacturers provide the basic instructions along with their products. Further, we recommend that if somebody is installing a rack for the first time, that they work with somebody that has done it before and knows all the myriad details and potential problems that folks might come across. Hope that helps explain it. Michael for HP.

fotovoltaika's picture

Interesting article

Scott Russell's picture

We're glad you think so. Racking is a highly innovative area of the solar equipment landscape. In recent years, it seems like Home Power is constantly publishing new articles on pioneering racking developments just to keep up.

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