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Betting on solar power in Vegas

MGM Resorts International is betting on renewable energy in a big way, with a solar power project?"one of the largest rooftop solar arrays in the U.S.?"on the roof of the Mandalay Bay Convention Center in Las Vegas.

By Paul MacDonald

With the solar power project on the roof of the Mandalay Bay Convention Center in Las Vegas, convention center owner MGM Resorts International is betting on renewable energy—in a big way.

MGM Resorts and NRG Energy Inc. recently completed expansion of one of the largest rooftop solar arrays in the U.S., at the Mandalay Bay Convention Center.

The solar array has more than 26,000 photovoltaic panels and produces 6.3 MW of electricity; a recent expansion has an additional 1.9 MW, and the numbers are impressive. At full production, the system supplies 25 percent of the power demand of the entire Mandalay Bay Resort and Casino campus, and the electricity produced is equivalent to the average annual energy use of 1,340 U.S. homes.

And the high-profile project has generated plenty of buzz. Guests who have toured the facility include President Barack Obama, former Secretary of State Hillary Clinton, and U.S. Energy Secretary Ernest Moniz.

Since completion of the first 6.3-MW phase in 2014, the project has helped provide pricing stability for MGM Resorts, while reducing the amount of energy drawn from the southern Nevada grid during times of peak electricity demand.

"MGM Resorts International has a long history of integrating environmentally responsible practices throughout our operations," said Cindy Ortega, senior vice president and chief sustainability officer of MGM Resorts International. "Our continued partnership with NRG inspires our desire to continually implement innovative solutions that promote renewable energy."

The 1.9-MW phase two of the project uses state-of-the-art technology from solar component supplier, Ten K Solar. Ten K's REFLECT system consists of 4,644 modules, 180 inverters, and a fully integrated Ten K racking system with no roof penetrations. The racking system uses 3M Cool Mirror Film to reflect only the light wavelengths usable by the photovoltaic cells. Ten K's parallel cell and module architecture allows modules to capture non-uniform irradiance coming from reflected light. The architecture further eliminates any single points of failure, increasing total system availability and reducing operation and maintenance costs, says Ten K.

"For phase two, we took a foray into the next generation of system design and engineering to increase the site's solar production and shading tolerance by deploying Ten K Solar's 3M REFLECT system," said Erik Linden, NRG's senior director, communications.

Static, selective film reflectors are installed on the backside of each wave of the array, increasing the amount of light on the panels and overall production, he explained. "These reflector panels helped create a more dense array, ultimately benefitting the economics of phase two. We're really excited about the Ten K solar technology and look forward to hopefully implementing it on future projects."

For phase one, NRG used an in-house EPC, and for phase two, Bombard Renewable Energy was brought on as the EPC contractor.

NRG owns and operates the installation for MGM Resorts. Through a 25-year power purchase agreement (PPA), Mandalay Bay Resort will purchase all the electricity generated by both phases of the solar project.

Helping the economic feasibility of both projects was that NRG was able to utilize renewable energy tax credits, and MGM Resorts secured a private buyer for the renewable energy credits (RECs).

From the beginning, the project was planned for two phases.

"After phase one, we also had this great opportunity for phase two at Mandalay Bay because we were replacing a 22-acre roof," explains MGM's Cindy Ortega. The company was also expanding the convention center, a project that had been planned for some time, but had been rescheduled due to the economic downturn.


One of the major goals of the solar project is to illustrate the company's energy leadership. "The story is about more than electrons simply coming off the solar array," says Ortega, who has been a driving force for clean power at MGM Resorts. In fact, Ortega was recognized by Green Building & Design as one of the 10 Most Powerful Women in Sustainability in the U.S. in 2014.

"You often hear in the sustainability movement that business can be one of the primary vehicles to get renewable energy done—in fact, this solar project is a classic example of how a business can accelerate the adoption of alternative energy technologies.

"And it not only provides power to Mandalay Bay, it also provides resiliency to our company in the case of power disruptions here in Las Vegas," she added.

Clean energy and energy efficiency have evolved greatly at MGM, says Ortega.

That started with a significant commitment of $6.5 million to make the company's properties more energy efficient.

"We invested that money in energy efficiency because there was a lot of low hanging fruit, in what we could do. And there were quite a lot of advancing technologies in the energy efficiency area that we could take advantage of," she explained. The company has a comprehensive program, Green Advantage, which uses environmentally responsible practices to effectively lower its carbon footprint throughout its operations.

Around that time, the company started looking more "big picture" at sustainability and clean energy and carried out several feasibility studies on large-scale solar arrays, including both ground-mount and roof-mount arrays. At the same time, the cost of solar power components was falling—and still is today.

"It was starting to get closer in terms of the return on investment," says Ortega. "The cost of the panels was coming down, and it wasn't such a stretch to build a large solar array."

The first phase of the project, completed successfully in 2014, consists of a 6.3-MW solar array, which has SMA inverters and utilizes Hanwha (QCell and SolarOne) as well as Canadian Solar panels. It covers 20 acres of roof on the convention center and neighboring buildings. Unirac supplied the racking for phase one. Power management company Eaton provided electrical distribution equipment. Sunora Energy Solutions did the installation of phase one, and it went very smoothly, reports Ortega.

"The planning on the first phase and the actual construction of the array was one of the most problem-free projects I've overseen," she said. "It was carried out really well."

With solid planning, building phase one was relatively straightforward. "To avoid business disruption, we redeployed or suspended construction activities at certain times," says Ortega.

"I think that clear communication of our needs, in terms of our customers, was key to the project's success. For us, the most important part of us getting this array up and going was that we were able to do it in a way that didn't disrupt the business operations for our customers.

"A second key was the capabilities of the array—making sure it was configured in a way that it would perform with minimal maintenance and downtime.

  At full production, the solar project supplies 25 percent of the power demand of the entire Mandalay Bay Resort and Casino campus, with the electricity produced equivalent to the average annual energy use of 1,340 U.S. homes.

"And so far, the performance of the array is exactly as it was projected, in terms of energy output. We've had no panel issues, no reliability issues—no issues period, really."

A safety practice that was established during the building of phase one, and which was carried over to phase two, was a well-established hydration program for construction workers.

"A challenge building a solar array in Las Vegas is that super heat," says Ortega. "Even though the roof is white, the fact is it is still 110 degrees on that roof. So with NRG, we established a hydration initiative that established standards about water and shade for the workers on the project. We were very conscious of that."

With phase one of the project, construction began in July, one of the hottest months, when temperatures soar well above 100 degrees, added NRG's Erik Linden. "Buddy systems were implemented as well to make sure everyone stayed hydrated, and workers looked out for each other for any symptoms of heat stress." Part of the construction plan included starting work early and finishing work early.

In the summer months, the sun comes up really early in Las Vegas. Construction crews in the city are usually done for the day by two in the afternoon.

Crews working on the Mandalay project would start by five or six in the morning, which helped deal with the heat, and it also helped manage the possible business impact to the convention center.

Components, such as solar panels and racking, were staged off-site and brought to the site on a just-in-time basis. NRG relied on a rented warehouse and a contractor's warehouse for some of the staging.

Since NRG was working with a brand new roof with installing the phase two project, there was not a lot of prep work required. Some holes were required for the conduits and structural support, but work was minimal. They used ballast-only racking, so roof penetrations were not required.

Throughout both phases, Ortega emphasized, Mandalay Bay and NRG worked through the challenges of the project. Life in Las Vegas never slows down, so the logistics of getting the sheer volume of materials and equipment—navigating through the city—on the roof while adhering to the busy schedule of the Convention Center sparked a challenge that MGM and NRG worked through together.

"It's so much different doing a roof-mounted solar array in a city of two million people versus out in the desert," says Ortega. Security is high for any conference center, and the logistics of hundreds of construction-related trucks and workers entering the site had to be managed carefully.

"Careful coordination with our partners was paramount with the constant activity of the convention center," says Linden. "The property itself was large enough to contain our own traffic, but there was a lot of working together to avoid any back-ups or jams. Craning plans were submitted every week so that both the construction and convention schedules could stay aligned. Trucks would be sent to staging areas to wait until it was clear for them to load or unload."

The logistics of getting the sheer volume of equipment and materials-including thousands of solar panels-on to the roof while adhering to the busy schedule of the convention center sparked a challenge that MGM and NRG worked through together.  

A long-reach crane loaded the materials and equipment to the roof and "Roof Buggies" were used to quickly move the materials to designated load points. Some small loads and tools were brought up using a bucket and pulley system mounted on the access scaffold or moved through the building when the convention center wasn't active. Scaffolding was also built to facilitate movement of workers, as the only permanent entrance was through the main floor.

"On the roof, we were limited by how much weight could be staged at any of the designated load points," said Linden. "NRG worked very closely with the structural engineer that designed the building to ensure that the materials and equipment were distributed in a way that would not overstress or damage the structure. A crew on the roof safely and efficiently distributed everything to where it was needed after unloading."

For the project itself, phase two required more shade-tolerant technology. The panels from the second phase are subjected to more shading due to the 18-foot-high "parapet" walls and the way the buildings are situated.

They were able to take some direction from phase one to work on phase two.

"One of the key learnings from phase one to phase two is that with phase one, we were so delighted to have a solar array going ahead that it did not occur to us that it would have any delays—and it did slip a bit from the schedule," says Ortega.

"With the second phase, we were waiting a short time for a new building to be complete—but it was a bit shorter timeline than the first phase."

Ortega agreed that it makes a huge amount of sense to tap into the ample solar power potential of Nevada. But there is still the issue of solar power being intermittent.

"A challenge lies in building, marketing, and bringing to market the availability of battery storage technology," she said. But Ortega believes that storage advances will be coming—and soon.

As an aside, certainly battery storage manufacturing for cars will soon be in Nevada.

Electric car company Tesla broke ground in June 2014 on what it calls its "Gigafactory" outside Sparks, Nevada, and expects to begin cell production in 2017. By 2020, the Gigafactory will reach full capacity and produce more lithium ion batteries annually than were produced worldwide in 2013.

Specific solar power infrastructure was required at Mandalay Bay. The local utility, NV Energy, did not want the Mandalay Bay solar project connected or delivering power to their grid.

"So we had to invest in equipment that would make sure that if the solar array went down, we would still get power from the grid—but that the array would never deliver power on to the grid," explained Ortega.

MGM and several other U.S. companies have recently entered new territory in that they have chosen to become a competitive customer for power—as of October 1, the company was purchasing its own electricity on the wholesale market.

"We are one of the largest companies in the U.S. to leave the utility system," says Ortega. "And one of the reasons for that is the company's desire to have control over the amount of renewable energy we are able to procure."

She said the company is considering the best business model to increase its investments in renewable energy, going forward.

"Do we figure out ways to build more rooftop solar? Or is it more viable for us to buy renewable energy on the open market? Should we be co-investing with other companies in solar projects around Las Vegas?

"We don't know the answer to these questions yet—and the answers may change or evolve over time," says Ortega. "I do know it is an exciting challenge to have because wind and solar power is available to MGM Resorts, and we believe we can bring our power portfolio up to greater than 50 percent renewable energy, through intelligent investing.

"It's a large job—but then a 28-acre solar rooftop array is a good start. Our message going forward is that we think renewable energy is a business imperative for us, and we believe in the benefits of investing in renewable energy—and we're going to do that."