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Solarwind power combo for Arizona

The Red Horse 2 solar/wind project in Arizona is one of only a handful of utility-scale combined solar/wind projects in the U.S., and it involved some very close coordination by the contractors involved with the project, Swinerton Renewable Energy and IEA

By Paul MacDonald

The Red Horse 2 project in Arizona is one of only a handful of utility scale combined solar/wind power projects in the U.S., and with it came a few different challenges compared to building a strictly wind or solar project.

Development of the 71-MW Red Horse 2 project began in 2011, to satisfy a power purchase agreement secured with Arizona utility Tucson Electric Power in 2013.

Groundbreaking for the project, which is located near the town of Willcox, about 80 miles east of Tucson, took place in November 2014, and it was completed in the summer of 2015.

Swinerton Renewable Energy designed and built the 55-MW solar portion of the project, taking on building both the solar power and substation components. IEA built the wind power section, which features 15 Vestas V110 turbines.

As with many of the renewable energy projects Swinerton takes on, the company worked to do as much of the project itself as possible.

"We try to do just about everything we can—we're big on self-performing," explained Brian Hoopes, project manager for Swinerton on Red Horse 2.

"With a design/build project like Red Horse 2, the developer provides us with the parameters for the project, and we begin working with our design partners to maximize the energy output of the site, looking at the different wattages of modules, ground cover ratios, and different array layouts to maximize the output for the project owner.

"We'll start right away with various layouts and PV model systems to help the owner meet their financial price-points," Hoopes added.

Blymyer Engineers, a leading utility scale solar design and engineering firm, was selected as the engineering firm of record for the solar portion of the project. "We've worked with them on a regular basis—they are trusted design partners for us and have helped us design and build dozens of projects," said Hoopes.

IEA did the design/build for the wind power aspect of the project.

"We helped coordinate the wind power part of the project, with IEA," said Hoopes. "Swinerton built the new substation and 13 miles of transmission line, and all of this needed to be coordinated with the wind project design, so the conductor sizing and the transmission line and the breaker sizing at the substation were well coordinated with the wind project right from the start."

A combined solar/wind project offers the potential for more steady—rather than intermittent—power production, Hoopes notes.

"It's an interesting concept because there is the potential for delivering power around the clock—you get solar power during the day, and then as you get the thermal differences in temperatures late in the day and at night creating some wind and wind speed, there is the opportunity to ramp up your wind power later in the evening and overnight as the wind continues to blow."

This was the first hybrid solar/wind power plant Swinerton had been involved with, and the company was very interested in working on the project from the get-go, Hoopes says.

"As soon as we heard about Red Horse 2, we wanted to be involved with it," he added. "It's an intriguing project. It's definitely a large scale effort—it takes a lot of land and a lot of effort on the development side to put together all the approvals to do a project such as this."

And projects that, by design, include both solar and wind tied together are still fairly uncommon. "There are other facilities out there that have solar adjacent to wind, but they usually have their own separate substations for stepping up that power and delivering it to the grid for utility use. With Red Horse 2, it's unique in that, while solar has its own transmission line, and wind has its own transmission line, they go to a common substation and common BUS and main power transformer."

 Swinerton Renewable Energy designed and built the 55-MW solar portion of the Red Horse 2 project, taking on building both the solar power and substation components. On Red Horse 2, they used Array Technologies single axis trackers, some 248,000 Jinko 305 watt modules, and Advanced Energy 1000NX inverters.

In terms of tackling solar projects such as Red Horse 2, Hoopes explained that Swinerton essentially approaches projects from one end of the site, proceeding systematically to the other end, rather than doing it in phases.

"We prefer not to phase the work—we like to have our equipment and manpower in there and to flow through the site. We find that kind of flow keeps our crews working actively, and we are able to meet the productivity levels that we need. There's even a bit of competition between the crews," he added.

On the solar side, the workforce, including supervisory personnel, peaked out at around 250 people. Staffing firm Aerotek assisted with supplying labor for the relatively remote location.

"The wind power side with IEA peaked out at around the same time, with about 80 people, so we had a total of about 330 people on the site at its busiest time," noted Hoopes.

Some civil work was required on the solar site, but it was not extensive. "A lot of that depends on the racking that is used—it has various tolerances for grade and sloping for it to operate effectively. With the Red Horse 2 site, we were able to utilize a lot of the existing ground and grade—the entire site was generally south sloping, which was good for the project, so we did not have to adjust a lot of the grades."

Much of the civil work involved building roads to the site, and throughout the site, for construction as well as operations and maintenance over its 25-to 35-year life North Carolina-based Kimley-Horn was the contractor for the civil work required for the solar project. In addition to doing the design/build, Swinerton also has the contract for ongoing operations and maintenance of the project.

Hoopes reports that access to the site area was reasonably good, for material deliveries and getting equipment and people on site. Interstate highway I-10 goes through the nearby town of Willcox, which is about 80 miles north of the Mexican border.

Having the interstate helped with transporting material and equipment into the region. "The site itself, though, is about 40 minutes west of Willcox, and part of that was paved county road and part was dirt and rock county road—there was a lot of native hard rock that gave us a few flat tires on that section of road."

Though it was usually brief, they did have some heavy rain that made the dirt road impassable at times—except for four-wheel drive vehicles.

That said, due to the timing of construction, they had pretty good weather on the site. Construction started in September 2014 and was basically completed by the early summer of 2015, followed by several months of testing and startup procedures. "We had some heavy rain, and with it being high desert, we even got a bit of snow, and some high temperatures in the summer. But we were able to avoid most of the monsoon season with the work on the site," explained Hoopes.


With the site's high elevation—4500 feet—there were no issues with some of the more common desert endangered species, like tortoises. There was one cultural site that they worked around. "We used an anthropological firm that came and monitored the work we were doing adjacent to this area to make sure nothing was disturbed."

Since Red Horse was a design/build project for Swinerton, it selected the components for the projects, on behalf of the owner.

"We work with a regular group of suppliers, and we always try to get the best prices for the project owners and developers, to meet their price points," says Hoopes. "We work with various vendors in the industry with similar products to get good pricing, to keep it competitive."

On Red Horse 2, they used Array Technologies single axis trackers, some 248,000 Jinko 305 watt modules, and Advanced Energy 1000NX inverters.

As both the solar and wind power projects on Red Horse 2 proceeded, there were regular meetings between Swinerton and IEA, which was working away on the wind portion of the project, with the Vestas turbines.

"At a minimum, we had weekly meetings to make sure we were discussing each other's scopes, and that we were all on board with what each other was doing," says Hoopes. "Swinerton had safety oversight for the entire project, so we reviewed IEA's safety plans. But given IEA's experience in the construction industry, there was no need to micro-manage them. They did a great job."

There was a fair amount of just exchanging day-to-day information between the two companies at points, he added.

"Swinerton was in control of the substation and the transmission lines, and as we neared energization, we needed to make sure that our safety processes and all of our lockout-tagout procedures were in place to make sure that as we energized the transmission lines, and up to the sectionalization cabinets and switchgear, IEA were aware of when we were going to be flowing power so they could safely start up their site."

Hoopes explained that there were several factors that led to the successful completion of the Red Horse 2 solar project, including the supplier approach Swinerton takes on all of its projects.

"A lot of our success comes with our vendor relationships—they fully understand our timelines for procurement and delivery. We are able to keep close tabs on when we need to start material deliveries, to get it on site to support the installation process. We want to make sure we are not waiting for components to show up—we don't want to have to de-mobilize our crews because we don't have materials on site.

"We were able to schedule the Red Horse 2 project well because we have close relationships with vendors in the industry—that was a great help."

Materials were delivered to the site as they were available, rather than having a focus on just-in-time deliveries.

"I think just-in-time delivery makes sense for certain projects, where you have a small footprint or laydown area," said Hoopes. "But with a project like this, where we had ample room for laydown and materials storage, I wanted to get materials to the site as quickly as possible, regardless of whether we might need to double-handle them.

As both the solar and wind power projects on Red Horse 2 proceeded, there were regular meetings between Swinerton and IEA, which was working on the wind portion of the project, with its 15 Vestas V110 turbines. Weekly meetings were held between the two firms, to share information about their respective parts of the overall project. 

"Even the double-handling pays for itself when you are able to keep people working consistently and productively, without having to wait for materials to show up."

There are also the unexpected events that can cause hiccups to just-in-time deliveries when components are coming from overseas—such as the strike earlier this year at the Port of Long Beach, California, through which solar panels are brought into the U.S.

"That could have impacted deliveries—we could have had our panels sitting offshore in a ship, waiting to be unloaded," said Hoopes. "Luckily, we had received enough materials that it did not affect our productivity, but it could have easily had an impact. I was very happy we had stockpiled material on site."

Just as the solar portion of the hybrid project was interesting for Swinerton, it was also a project that consulting engineers Blymyer Engineers were keen to be involved with. Blymyer has done a lot of projects for Swinerton in the last half-dozen years. Although they started out as a general contracting consulting firm in 1961, about 80 percent of their work is now in solar PV. Blymyer Engineers completed over 408 MW of projects in 2014.

Blymyer president Michael Rantz noted that Blymyer worked very closely with both the project owner and Swinerton on the solar aspects of the Red Horse project.

"We developed very intense energy modeling for the sites, looked at various layout options and different technologies," he said, adding that it is important—and beneficial—for consulting engineers to be involved right through planning and into construction of a project.

"We're going back and forth with the EPC, working with them to fine-tune the design, how deep the trenches should be, where to put the combiner boxes, where to put the inverters, and coordinating the overall design with the substation design. There are so many variables with a solar project—but we're used to it."

Working together with the developer and EPCs such as Swinerton, consulting engineers can help achieve cost savings by directing efficient approaches to building a solar project, he says.

"The larger the project, the more critical your decisions can be in terms of cost savings—we want to help deliver the best financial model for the developer," said Rantz. "Working with the developer and the EPC is critical—it's what we do."

Sometimes the choice of project components—racking, panels, inverters—can be an evolving process, depending on cost and availability, he added.

The Red Horse 2 solar project posed a challenge in that it is made up of three different sections, separated by an unbuildable flood plain area in the middle. "The collection part was challenging because of that," said Rantz.

Swinerton's Brian Hoopes said one of the most important aspects of the Red Horse 2 solar project was the SCADA (Supervisory Control and Data Acquisition) system at the substation.

"It's something amazing that the Swinerton group put together," he explained. "Since Red Horse is a hybrid project, wind and solar come to a common BUS on the substation transformer. There is a plant controller for the wind project that the wind turbine supplier, Vestas, supplied. And we supplied a plant controller for the solar side."

Swinerton's SOLV (System Operations Live View) division, which evolved out of the company's capabilities as an EPC, developed a master plan controller that controls the solar controller and the wind controller.

"We had to create a hierarchy of system controls at the substation to meet our obligations for power generation and the utility's requirements for control of the system."

As the Red Horse project drew to a successful conclusion this past summer, there was a sense of achievement by all the parties involved in this hybrid project—and also a desire to do more such projects.

"We're happy to add this to our company and project portfolio," says Hoopes. "It's been an interesting project for us—and I hope we can work on something like the Red Horse 2 hybrid project again."