The art of anchoring solar arrays
08 / 2010, Applications & Installations | By: Ucilia WangMounting systems: As the U.S market takes off, mounting system developers are rolling out designs that aim to shave installation costs for commercial and utility-scale projects.
In North America, everyone wants a piece of the utility market. That desire manifested itself during Intersolar in San Francisco in July, when mounting system makers showcased designs for propping up solar modules on the ground and flat rooftops. In the United States, mandates from about two-thirds of the 50 states are requiring utilities to sell renewable electricity. Utilities either buy the clean power from independent power producers or generate their own. In Ontario, Canada, the feed-in tariff policy has created a boom for large-scale projects. The utility market, it would seem, is where handsome profits could be made.
So American companies that have initially offered rooftop solutions have started to offer ground-mounted racks as well. SunLink and PanelClaw are among those who have launched ground-mounted systems over the past year. More seasoned suppliers such as Unirac also started peddling mounting systems for large-scale deployments in 2009. Cooper B-Line, meanwhile, launched its first mounting system ever, a rooftop design called Arista, at Intersolar North America. The company plans to introduce a ground-mounted rack this fall, says Todd Davis, a Vice President of the company.
European companies, too, are not sitting idly by. In fact, Hilti Group, based in Liechtenstein, announced in May its acquisition of Unirac. Germany-based Schletter showed off its hardware during Intersolar North America.
Most of the companies use aluminum or steel as the main material and devote their ingenuity to the design of fasteners and their placements, ballasts of various sizes and configurations for anchoring the array, and grooves for adjusting the tilt of modules in varying angles to maximize their exposure to direct sunlight.
One of the key goals is to design a rack that can improve wind and earthquake resistance of the modules, which resemble rows of sails. Cutting labor costs is another aim. Preassembly or prefabrication are the buzz words from mounting system designers as they attempt to explain the ease and speed with which the various parts could quickly fit together for installation. Some companies say they not only preassemble the racks, but also the modules onto the racks before shipping them to a job site.
Racks could account for five to twelve percent of the total costs (equipment and labor) of building a solar field, depending on the size and location of the project. Labor alone could account for 20 to 30 percent of the total costs.
“You want those panels to stay there forever. We are watching for innovation relative to simplicity and labor costs,” says Tom Hunton, CEO of American Capital Energy, a project developer. “The installation time is only part of the puzzle. Is the mounting system compatible with our site, how strong is it, how flexible? We will take a sample and test it ourselves.”
Understandably, competition is getting intense. And it’s not just among rack suppliers. Some module makers and installers also have taken a keen interest in developing their own mounting systems and hiring factories to produce them. They believe doing it themselves could cut costs while addressing some of the shortcomings they see in off-the-shelve mounting systems.
The solar industry is relatively young and lacks standardization in module sizes and frames. It is also going through a learning curve to install what are essentially large electrical systems that could pose significant fire hazards. There are building and fire codes to follow.
“It’s sort of like the Wild Wild West – many people focus on their proprietary systems,” says Raymond Szkola, manager of engineering services at the mounting system supplier, Unistrut Energy Solutions. Szkola is referring to the variety of module sizes and frames. “You will see what systems will be successful over the years, and people will settle into certain designs.”
The slow rise of utility market
Over the past two years, American utilities, particularly those in the West, have signed mega power purchase agreements for electricity from gigawatts of yet-to-be built solar farms. At the same time, some of the utilities have also gotten approval for building their own solar power plants, some of which would be erected on leased commercial rooftops or school grounds.
The utility market is quite small at present – only about 160 megawatts have been installed, according to GTM Research. That’s a fraction of a single coal-fired power plant. First Solar and SunPower together own 74 percent of the installed market in the United States as suppliers, contractors and developers, says GTM’s Senior Research Analyst, Shayle Kann.
With more than a dozen gigawatts of power projects announced, the market seemingly teems with opportunities. How do you differentiate yourself from the rest of the pack? All mounting system designers have set out to design streamlined and durable racks that can accommodate modules from major brands, provide flexibility for tilting the modules, and make it easy for installers to deploy.
Take SunLink’s ground-mounted solution, which was launched last year and featured in a 1.2 megawatt project by BP Solar at the Palo Verde College in California. The low-profiled system is anchored by concrete ballasts and comes with screws atop the ballasts for leveling the solar arrays on uneven terrain that is up to five percent grade. The modules could do 20 degree to 40 degree tilt. SunLink says it would take a four person crew to install 300 modules in a 7.5 hour workday.
PanelClaw, too, emphasizes the simplicity and flexibility of its design. The ballast-based system, called Panda Bear GM, comes in three major components and two sizes for nuts and bolts. Feedback from customers has pegged the installation speed at 100 to 120 modules per 7.5 hour day for a three person crew, the Massachusetts company says.
Unirac, having celebrated its tenth year in the market in 2009, offers a wider selection of ground-mounted and rooftop systems. The company is marketing the ground-mounted ISYS as a one-fit for various types of foundation, from concrete ballasts to driven pile. It also could support six panels per column. The ability to pack them densely saves the costs of sinking pilings and adding concrete ballasts, notes Darren Womacks, senior director of manufacturing at Unirac. “The amount and price of land could be an issue, especially for modules with lower power densities,” Womacks says.
Aluminum and steel are two main materials for a racking system’s components. Aluminum is lighter weight and more flexible, but could be more expensive than steel. Manufacturers typically add coatings of zinc and other materials on steel to prevent corrosion over time. But some companies are experimenting with alternative materials. Sollega is one of them. The American company is using recycled polyethylene plastic for the bulk of the structure, along with steel struts and concrete ballasts. At least 35 percent of the plastic comes from recycled material, the company says. The company’s InstaRack is meant for flat rooftops.
“Plastic takes less energy to make. For LEED (Leadership in Energy & Environmental Design) certified projects, recycled content is one thing you can get points for,” says John Humphreys, President of Sollega.
Competitive landscape
Mounting system developers are finding themselves not only competing with new arrivals in their field, but also module manufactures and installers who have opted to design their own racks. The trend is taking place across residential, commercial and even utility markets.
SunPower is a good case study. The company is a big proponent of trackers for large-scale projects, and it uses its own trackers. SunPower also has designed its T5 modules, for example, to come integrated with racks for flat roofs. The company has also designed racks for its T10 modules go on flat roofs and on the ground. SunPower went to court over a patent infringement claim against SunLink. The two companies settled the lawsuit last year, with SunLink admitting it had infringed on SunPower’s patents and agreeing to license SunPower’s designs.
Akeena Solar’s integrated module-and-rack system, which was formerly called Andalay and now sports the Westinghouse Solar brand, is designed for residential roofs, carports and other commercial locations. Peter Rive, co-founder and COO of SolarCity, an installer in California, says the company has opted to design its own mounting system for the residential market.
SolarCity does buy racks from vendors for flat-roof, commercial projects. “It’s more economical for us to design our mounting system at the volume and scale in which we install,” Rive says. “There were some issues that we didn’t see the industry addressing: it had to do with combining adjustability and waterproofness.” Market opportunities often drive innovations. The drive to reduce the cost of solar electricity will continue to push for more efficient designs and materials for mounting systems. And that is good news for investors, project developers and consumers.
