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Going big with Cali solar project

Rosendin Electric is working with SB Energy to build a 450 MW solar project, which will cover nearly five square miles of Riverside County, California.

By Diane Mettler

When they say “go big or go home”, Rosendin Electric is serious and goes big.

The Rosendin Renewable Energy Group (RREG), one of the largest employee-owned electrical contracting companies in the U.S., was contracted to design and build one of the largest solar projects in the state of California by SB Energy US Holdings One, Inc., a subsidiary of SoftBank Group Corp.

This installation, called Athos I and Athos II, will cover nearly five square miles, a 3,440-acre land parcel located approximately 75 miles east of Palm Springs in a small town called Desert Center in Riverside County. When completed, Athos I and Athos II will generate over 2,200 GWh per year, which is enough electricity to power 179,000 homes per year and annually offset 1.7 million tons of carbon dioxide emissions. The Athos I and II projects total 640 MWdc/450 MWac.

For a solar array that covers nearly five square miles, it takes a tremendous amount of planning, development, and time.

“From design to finish, it has taken two years,” says Rick Gonzales, Division Manager for Rosendin, overseeing the Athos projects' work. “The construction cycle on each phase takes approximately 10 months. We're close to 100 percent done constructing Athos II, and Athos I is nearly 60 percent finished, with completion expected in February 2022.”

As of December, Athos II was in the middle of final completion activities required to achieve COD (Commercial Operating Date). This is the hot commissioning phase, when all the equipment is tested, turned on and brought online.

The plan called for completion in December. “There is currently a team of 16 dedicated personnel managing this hot commissioning process,” Gonzales said. “That includes at least four of our guys working closely with the installed equipment manufacturers who are also on site testing, powering up the equipment and providing final certification for ongoing warranty support.


“Hot commissioning is one of the most challenging parts of the project because we are firing equipment up for the first time,” Gonzales adds. “You're working out all the kinks associated with a brand new project that's never been energized, so if there are manufacturing defects or other problems, you can have anything from overloaded circuit boards or blown fuses inside equipment containers.

“But that is why we have such a robust team from our side and the various manufacturers on site with the necessary expertise, equipment and replacement parts to facilitate working through this last phase of commissioning. Once the system passes final commissioning then the plant begins selling power to Southern California Edison.”

The Athos I and Athos II project is just one of many projects Gonzales manages simultaneously. He has an onsite team responsible for overseeing the construction, and visits the site personally about 10 days out of the month.

“From the get-go, we deployed a collaborative planning process with Softbank that is based on the philosophy of Integrated Project Delivery (IPD),” says Gonzales. The IPD approach to new construction was adopted many years ago for large scale, very complex, new construction projects that require a high level of collaboration and integration of all stakeholders in the development, planning and implementation aspects of the project, to assure maximum cost and schedule efficiencies. So for Athos 1 and 2 RREG and Softbank teamed up with all the project participants, including supply chain providers, subcontractors and the International Brotherhood of Electrical Workers (IBEW) labor team, to assure everything went smoothly through the various stages of development and building.


For the combined solar projects, Rosendin needed to acquire 77 grading and building permits through Riverside County plus 129 CUP (Conditional Use Permit) Conditions. The permits and conditions ranged from environmental issues, to line safety, to the removal of over a thousand date palms.


“That way, everyone is on the same page, understands their respective roles and really know what is going on,” Gonzales adds. “We can be assured people know who is accountable and responsible for what, when, and where. It is what is necessary to make a project of this size run as smoothly as possible.”

After the design work was completed and approved, the next task was getting permits and, depending on which county you're working in, it can be complicated or relatively straightforward. Athos 1 and II were treated as one project for permitting purposes. Even then, Gonzales ran into a few challenges. He needed permits from not only Riverside County, but from the Bureau of Land Management (BLM) and the Seboba, Agua Caliente, and 29 Palms Indian tribes, all during a pandemic.

For the project alone, Gonzales needed to acquire 77 grading and building permits through Riverside County plus 129 CUP (Conditional Use Permit) Conditions. The permits and conditions ranged from environmental issues, to line safety, to the removal of over a thousand date palms.


“It took probably five months to get my permits due to COVID and all this was happening at Christmas time,” Gonzales says. “To be honest with you, it's probably one of the most difficult projects I've ever had to deal with due to the fact we were working with three different entities between the tribal communities, and Riverside County.”

The land had also been used as part of General George Patton's training grounds during World War II. On two occasions, the workers discovered what looked like unexploded ordinance and, following protocol, contacted the sheriff's department who sent out a bomb squad. “We saw something that looked funny and they came out and took care of it,” Gonzales says.

When it came to the actual construction, the pandemic caused some issues. “You can imagine what challenges we faced given not just the limitations the pandemic placed on worksite conditions, but also the pandemic-related relief funding impacting our recruiting efforts. For a lot of folks, it paid more to stay at home than go to work,” Gonzales said.

“But by the time we cleared through everything, we built a good solid team. We had a maximum of 500 individuals on site—a total between all the trades. Onsite, RREG had an in-house staff of approximately 22 for the project. The rest of the labor force for both Athos I and II came from the local union halls as the IBEW constructed the project, following all COVID-19 safety protocols.”

When completed, the Athos I and Athos II solar projects will generate over 2,200 GWh per year, which is enough electricity to power 179,000 homes and annually offset 1.7 million tons of carbon dioxide emissions. 

Before equipment delivery could be made, RREG had to fill in koi ponds, remove trees, demo two houses and one barn, and build 54 miles of road infrastructure. “We control the deliveries flow so we live stage, which means once it comes off the truck, we put the panels and trackers out where they are going to be installed,” Gonzales said. “I was averaging about 40 to 50 delivery trucks a day.” Not surprising when the project required nearly a million-and-a-half solar panels, alone.

To get an idea of the immensity of the projects, the equipment line up says it all.

For Athos I, which was 357.15 MWdc/250 MWac, the necessary equipment delivered and installed was as follows: 821,034 First Solar Series 6 modules, 10,336 NEXTracker Horizon single axis trackers, 126,825 NEXTracker foundation piers, two substations, and one shared switchyard. 

And with Athos II, which was 284.43 MWdc/200 MWac, it included: 653,868 First Solar Series 6 Modules, 108,978 dc strings, 8,379 NEXTracker Horizon single axis trackers, 101,100 NEXTracker foundation piers, and one substation.

TMEIC Ninja 840 kW inverters were used on the project. There are five inverters per inverter skid assembly. On Athos I, there were 72 TMEIC inverter skid assemblies, for 360 Inverters, and Athos II had 58 TMEIC inverter skid assemblies, for 290 Inverters.

 The Athos I and Athos II solar project site will cover nearly five square miles, a 3,440-acre land parcel located approximately 75 miles east of Palm Springs in a small town, Desert Center, in Riverside County.

As the summertime temperatures rose to 126 degrees Fahrenheit, the desert heat was the biggest challenge during construction. To combat it, crews began their days in the early morning hours.

“Every 10 minutes, the guys had a water break,” says Gonzales. “And if they want to go home after 10 a.m. or it reaches 115 degrees, they have the right to go home, and a lot of them would. We bought all the staff special long-sleeved shirts to wear that helped hold the cool in and which also kept them from getting sunburnt. We provided shade hats, cold water, ice…lots of ice.”

And not just the workers were affected by the heat. The variable speed motors inside the trailers' air conditioning units would shut off around 1 p.m. because the temperature was so hot inside the units.

“The heat probably began the second week of July and went through August and then two weeks into September,” says Gonzales. “Those were the most brutal periods—I would go to my truck and it would be 141 degrees Fahrenheit inside the cab.”

Despite all the challenges, what Gonzales is proudest of is being able to complete the project on time.

And going forward, the future of the solar industry, and the renewable energy in general, is bright.

“Rosendin's business development department gets calls all the time, and the projects are starting to get big, bigger than what we used to get,” says Gonzales. “Before, 20 megawatts was considered a large project. Then they went to 50 megawatts, then we did a 100 megawatts installation. Now it seems like the smallest we see are 150 megawatt projects with our average trending upwards of 300 MW.

“The Athos I and II projects total to 640 MWdc/450MWac. Right now, I'm looking at a project for 900 megawatts in La Paz County in Arizona. Another division manager is working on a 700-megawatt project on 3,200 acres in Texas.”

Rosendin has now established itself as a leading EPC (Engineering, Procurement and Construction) builder of mid to large-scale solar photovoltaic systems throughout the United States. It has two divisions on the West Coast and one on the East Coast focused exclusively on utility scale solar. RREG also has divisions that focus on Commercial Distributed Generation renewable energy projects, battery energy storage projects and high voltage/medium voltage services for the wind industry.

“I think by the end of next year we will have another division in Texas. We want to aggressively grow the business,” Gonzales says. “Currently we're working on a strategic plan to do that over the next five years. I would say that as a group we're planning to grow at least 10 percent year over year, expecting to reach over 3 GW of annual solar PV plant installations by 2026.”

And will Gonzales be a part of the surge in solar energy? “I've got a few more years in me,” he says. “Over the next couple of years, I want to go do a few projects in Arizona or Nevada.”

Q1 2022