America's largest solar power project well underway
Invenergy's?1,310 MW Samson?Solar Energy Center in Texas will be the largest solar power project in the U.S., and the project came with some interesting challenges, including overcoming some difficult site conditions.
By Robin Brunet
Considering how much size matters to the success of solar projects, it's inevitable that records continue to be broken in terms of the sheer scale of installations and the power they generate–and the latest king in the realm of renewables is the Samson Solar Energy Center.
Located in northeast Texas, the Samson Solar Energy Center developed by Invenergy unseats the Solar Star photovoltaic power station near Rosamund, California as the largest solar installation in the U.S.
Compared to Solar Star–which is spread over 13 square kilometers and produces 579 megawatts–the $1.6 billion Samson project will generate 1,310 MW of sustainable energy, enough to power 300,000 American homes, when completed.
Plus, over the life of the project Samson will directly invest $450 million in the local economy through new tax revenues and lease payments to participating landowners. It is already supporting up to 600 jobs during the 36-month construction phase and will create 12 permanent operations and maintenance jobs.
For Chicago-based Invenergy, Samson augments a portfolio of large-scale energy generation and storage facilities that the company has developed, owns, and operates throughout the Americas as well as Europe and Asia.
"I would describe Samson as a real showcase of our expertise," says Utopia Hill, Invenergy's Vice-President, Renewable Engineering and Project Management. "We were extremely fortunate to have secured the 18,000 acres necessary for this project. The construction process is going very smoothly, and we anticipate a completion in 2023."
It would be an understatement to say that financing the project was an exercise in complexity. Construction financing for the first phase of the project was announced in January 2021 after years of behind-the-scenes work, and in June 2021 Invenergy completed financing for the second phase, including 250 MW of the total 1,310 MW output. Santander acted as the coordinating lead arranger, and Bookrunner, and Societe Generale, and CaixaBank were the joint lead arrangers.
Anneli Alers, Senior Vice-President, Finance and Capital Markets at Invenergy, described the second phase financing as "a significant step forward in the completion of the record-setting project," and she added that, "this milestone is a testament to Invenergy's strong relationships and long-standing track record with our financial partners."
AT&T signed a power purchase agreement for 500 MW in November 2020; the remaining capacity was sold to four commercial/industrial customers and three Texas municipalities, including Honda (200 MW), McDonald's (160 MW), Google (100 MW), Home Depot (50 MW), Bryan Texas Utilities (100 MW), Texas A&M University (50 MW), City of Denton (75 MW), and Garland Power & Light (25 MW), through long-term power purchase agreements.
Equally complex is the construction schedule. Samson is being developed in five phases of 250 MW, 200 MW, 250 MW, 300 MW, and 310 MW capacities spread over Franklin, Lamar and Red River counties near the Texas/Oklahoma border. Development work for all five phases was completed by the third quarter of 2021, paving the way for the third quarter of 2023 construction completion target.
Hill says much of the credit for the project's success to date goes to Invenergy's partners like FTC Solar, a global provider of solar tracking systems, software, and engineering devices, as well as builders TIC (The Industrial Company), a wholly owned subsidiary of construction company Kiewit that specializes in construction of renewable energy projects throughout the U.S.
Kirk Hayes, Vice-President of Construction at FTC Solar, says: "Much has been written about the geographical size of Samson, that it's the equivalent of over 13,000 football fields. But while the sheer size of the project is intimidating, that wasn't the biggest challenge per se: initially we had to contend with less than optimum site conditions.
"Still, with the systems we provided, we calculate that we have been able to reduce man hours of labor on site by 30 percent, with potentially more savings to come."
One reason for this efficiency has been organization of labor: Hayes, who like many of his FTC team is a former Marine, is adept at bringing order to what could easily turn into chaos, and he has helped standardize site tasks wherever possible–especially with regard to panel installation (there will ultimately be about two million of them, along with 80-plus inverters supplied by TMEIC and 14,000 tracker tables–with everything supported by just over 100,000 piles).
To ensure that the Samson solar project operates at peak efficiency when completed, FTC Solar's Voyager, a next generation, single axis, two-in-portrait tracker that reduces installation costs through patented design and superior engineering facilitating lean construction methods, was coupled in the project with FTC's Voyager Zone Controller, which provides a monitoring and control interface to the individual trackers within an array.
Another reason for site efficiency is what Hayes refers to as "FTC providing a smarter mousetrap. Our tracking components feature a simpler design with fewer parts, hence fewer things to fail, fewer piles to drive, and less cost, which is critical for a project of this magnitude."
The tracking system in question is Voyager, a next generation, single axis, two-in-portrait tracker that reduces installation costs through patented design and superior engineering facilitating lean construction methods. Ideal for bifacial panels, Voyager uses up to 56 percent fewer posts per MW, has up to a 41 percent lower installation time than industry average, and less than 210 Man-hr/MW to install. Its 2P configuration provides optimized panel performance as well as increased production–up to six percent–with SunPath solar backtracking and diffuse light capture.
To ensure that Samson operates at peak efficiency when completed, this tracking system is coupled with the Voyager Zone Controller, which provides a monitoring and control interface to the individual trackers within an array. The interface is used to view the status of the array, issue commands to one or more rows, and also control the array to maximize production and ensure safe operation. In extreme weather conditions, such as high wind or snow/flood events, the Zone Controller automatically commands each tracker in the array to stow at the safest angle.
The site conditions Hayes refers to consist of about six inches of fill on top of clay, meaning when it rains large swaths of the site get muddy–a situation that could have potentially slowed down pile driving. "So in order not to affect productivity numbers, we spent a lot of effort predetermining the best way of carrying out the installation process," Hayes says. "Again, Voyager was beneficial in that it requires only seven piles and holds more than 116 modules per row compared to the industry standard tracker design of 11 pile rows with fewer modules."
The Samson Solar Energy Center has a complex construction schedule. Samson is being developed in five phases of 250 MW, 200 MW, 250 MW, 300 MW, and 310 MW capacities spread over Franklin, Lamar and Red River counties near the Texas/Oklahoma border.
In July 2020, a TIC team headed by area manager Norm DeCastro began converting the farmland, with the goal of designing and testing new efficiency and safety methods without disrupting operations.
The soil drive times for posts differed throughout the massive site, but placing posts at the correct depth was rendered easier with new software and equipment. The 15 Vermeer PD10 pile driving machines used by TIC were each guided by an RDO/Carlson GPS, which can be remotely updated with the X, Y, and Z coordinates for each post. Two coordinates ensured that each post was installed at the correct location while the third designated the depth.
Additionally, TIC found a better way to install posts with a two-person crew instead of the traditional rig operator, skid steer operator, and laborer. TIC used a grapple attachment on the skid steer to grab the post and feed it into the machine, thus eliminating the need for the laborer. This strategy resulted in a 30 percent increase in efficiency and a reduction of 16,000 direct work hours.
Armed with about 500 scrapers, excavators, loaders, articulating dump trucks, skid steers, and utility terrain vehicles, TIC is also installing 70 miles of chain link fencing, 200 inverter skids and about 7,000 miles of cable throughout the Samson site.
In addition to its huge scope, the Samson Solar Energy Center also represents a social breakthrough of sorts: the project is being led by a team of women consisting of Invenergy developers Bristi Cure and April Christensen and Project Manager Utopia Hill. Cure, Vice-President Renewable Development, and Christensen, Senior Manager of Renewable Development, spent several years working to execute land agreements as well as build relationships with landowners, local governments, and other stakeholders.
Christensen also led the contingent of internal team members and external vendors to get the project construction ready, and Hill is overseeing the management of contractors, engineering partners, and equipment suppliers to ensure the smooth, safe, and successful completion of the project.
As of this fall, the Samson Solar Energy Center was rapidly taking shape. "Some areas of the site are completely done and wired and others are about 50 percent finished with panels awaiting installation," Hayes says. "About 64 to 70 MW are already capable, but this is just the tip of the iceberg compared to where we'll be by year-end."
For her part, Hill is satisfied with the progress to date. "Thanks to careful planning and the incredible coordination of our partners, the first three phases of construction are fairly advanced," she says. 'This is a great project not only for Texas but also our global portfolio."