A unique solution in the tracker industry developed specifically for commercial roofs is Edisun Microgrids’ recently redesigned dual-axis PV Booster. The new tripod-based tracker, which replaced the initial circular hoop base track, rotates 360 degrees, and at 33 inches high can withstand a 110 mph (177 km/h) wind, says Conrad Chase, Director of Business Development for the company. The panels on the dual-axis tracker yield 30% more energy than a 10 degree fixed tilt array, he says.
Edisun’s first commercial installation took place in October 2017 as a 1 MW array installed on 368,000 square feet (34,000 m2) of a cold storage industrial building in Oxnard, California. The project is comprised of more than 2,900 trackers, and thus far is the world’s largest rooftop tracker installation, the company says. The project’s energy generation will be used by the building tenant Chiquita Brands International, to reduce its refrigeration bill.
Edisun recently forged a partnership with JinkoSolar for the use of Eagle G2 modules in projects. Jinko’s new Diamond cell technology, a high-efficiency mono PERC design, allows the 72 cell modules to yield up to 400 W on the PV Booster. When bifacial panels are used on white commercial roofs, the albedo boost increases the energy yield by another 15%, Chase notes. “A white roof is California law now for new commercial construction, so this represents a very significant opportunity for us.”
Mining operations shed load
One mining operation that opted for an AllEarth dual-axis system is Stony Point Quarry in Cotati, California. The system is a 202 kW array using 33 AllEarth Solar trackers to substitute for about 50% of the quarry’s legacy electric consumption. New time-of-use consumers in the area pay over $0.30/kWh under California’s second round Net Energy Metering terms for late afternoon usage.
At the time of the installation, AllEarth CEO David Blittersdorf said, “In the residential and small commercial tracker market, one of the keys to success is channel deployment – essentially how you are reaching local installers, to pair your product with customers around the country. This is a vastly different market from the utility-scale tracker market.
“It’s critical to refine and enhance techniques for reaching the customer. It’s also an incredibly competitive space, with all the major residential installers competing for market share, even at a loss,” said Blittersdorf. “Dealers need to be able both to sell the value proposition to their customers, and to arrive on-site and efficiently install our product, so they make margin.”
Alion Energy is also providing trackers for sites with challenging terrain, mine tailings, rocky surfaces, capped landfills, and karst, notes Matt Galland, the Director of Commercial Operations for the company.
Alion’s unique mounting system uses slip-form concrete foundations, which cuts metal use in the system by one third of what a pile-driven system might require. Alion is supplying iEnergía’s
3.6 MW Calle Larga project, north of Santiago, Chile, where rocky soil precluded an economic solution for pile-driven systems.
Alion’s StormTracker single-axis tracker comes with a robotic cleaning system that uses the concrete foundation as the robot track. With the ability to contour the tracks along topography, and to ascend up to a 15 degree slope, the technology is being promoted in the MENA region at present. The robot is currently deployed on Alion’s 1 MW fixed-tilt project in Jalisco, Mexico.
Agricultural operations value footprint
When solar system vendors provide potential agricultural customers with a business case, they often need to show that the value of the savings from the solar project results in a higher return than the per-acre yield of the crop at the site.
For a solar project at Woolf Farming, in California’s Central Valley developer CalCom found that the gains from the Nextracker single axis-based 1.1 MW array outweighed the losses substantially, says CEO Dylan Dupre. “The Woolfs will enjoy projected annual savings worth $345,000 in the first year alone, and 85% of aggregated meters energy usage will be offset by solar,” he says. The decentralized design of the Woolf Nextracker system permitted an efficient use of an irregular section of land on a railroad easement, pushing trackers further into corners than a centralized tracker system might permit.
“On average, CalCom Energy customers who install a 1 MW solar array offset $250,000 in utility costs in the first year alone,” Dupre reckons.
High demand charges
Utility demand charges are often calculated on the basis of a customer’s peak usage on the day of the month that registers the highest consumption, resulting in lofty bills. “Demand-related charges usually represent 30 to 70% of most commercial customers’ electric bills,” according to one U.S. Department of Energy study.
So even if time-of-use charges are not applicable in a given utility territory, demand charges alone can still be onerous. One metal fabricator in the Escalon, CA area facing a high utility bill opted in 2017 for dual-axis Mechatron trackers for a 723 kW installation, in part due to limited available land for a single-axis farm, according to Michael Fakukakis, CEO of the tracker company.
“The company will see a return on investment within three and a half years,” says Fakukakis. Energy production at the site has been 3% higher than what was predicted by a PVSyst analysis of the project, thanks in part to a 99.9% uptime availability and improved temperature factor, he notes.
“Increases in energy revenue produced were further enhanced by the time-of-use rate structure,” Fakukakis says. “Our gearless dual-axis trackers produced about 21% more revenue than can be expected from horizontal single-axis trackers, and 45% more revenue than can be expected from fixed racks at the same site,” he calculates.
Mechatron used its own data collection in tandem with that of SolarEdge, which provided optimizers and inverters, to validate the data, Fakukakis clarifies. A significant hurdle that dual-axis system providers still face in the market is the potential buyer’s fear that maintenance will be crushing, and wipe out the nominal gains the technology offers over horizontal single-axis.
To assuage such fears, Mechatron offers a low-cost maintenance contract. “We offer an annual performance contract with guaranteed uptime of 99.6% for $300 per tracker per year or about US$0.01/W per year,” says Michael Fakukakis. “This contract supplements our 20 year limited warranty that covers all components of the tracker from abnormal events like extreme weather conditions or expected wear-and-tear operation,” he says.
Sensitive soil require ballast
The U.S. market for ballasted solar tracker solutions on brownfield sites is enormous, and the addition of solar revenue to landfills can often counterbalance a maintenance cost-driven balance sheet for the facility, turning it into a profit center. Solar FlexRack, for example, recently installed what the company calls “the largest solar project on a closed landfill in Maryland,” an 18.1 MW array at the Annapolis Renewable Energy Park.
The facility spans 80 acres (32 hectares) and was completed in mid 2018, generating enough clean energy to power more than 12% of the city’s homes annually, the company says. In addition to the solar energy, the city will receive over $250,000 per year by leasing the property to the project developer.
Other types of sites with sensitive soil surface issues include Native American lands where burial practices may include a broad and nominally unidentified spread of land. Alion Energy is currently completing such a project in Northern California where the tribe did not wish to have any ground penetration for a proposed solar system. The 10 MW tracker project is also located in an area with high volcanic ash content in the soil, so the Spot robotic cleaning system will help deliver a low LCOE, says Galland.
Charles W. Thurston