Blythe spirit: Where First Solar’s thin-film PV turns desert sun into grid-friendly juice

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Tom Cheyney
Tom Cheyney
Tom Cheyney, former senior editor of PV-Tech and Photovoltaics International, is now chief curator of SolarCurator.com and director of Impress Labs’ solar practice.

The road turns from rough pavement to graded dirt about a mile or so to the south of Interstate 10, just past the unincorporated community of Mesa Verde west of Blythe in southeastern California. Following 15th Street’s dusty grade beyond a funky residential neighborhood out into a mix of desert and agricultural lands, you soon come upon a large fenced-off area to the south that stretches for acres and acres. Inside the double-fence line is the Blythe solar project, the reigning (for now) largest thin-film photovoltaic power plant in the U.S.—and a harbinger of much bigger things to come.

First Solar engineering/procurement/construction arm developed and built the 21MW (AC) system in the latter part of 2009. The project started in early September, with clearing, grubbing, grading, and other preparing of the fallow 200-acre site over the course of a month, with the first of 47,000 posts (a little under a million kilos of steel) being jabbed into the desert floor in a 45-day stretch from mid-September to early November.

Once a few thousand posts had been driven into the dry, hard ground, the first of 47,000 tilt brackets (another million kilos plus of metal) started to be placed in late September/early October, a job that was completed in 38 days. Workers started installing the module support rails, horizontal beams, and other “table” components during the same timeframe and also completed that work in 38 days.

As the completed arrays started to sprout from the desert floor in early October, it was module time: 351,000 cadmium-telluride FS-275 panels, representing some 68 acres of glass weighing close to 3700 tons, was mounted three-high, clipped, and plugged in.

While the metal and glass was being put in place, other teams laid the cable: 127 miles of copper DC cable in 44,000 feet of trenches and 54 tons of HV AC cable in 18,000 feet of trenches—in 35 days.

Breaking it down from start to finish, including the seven weeks of engineering and 15 weeks of construction, the on-the-ground project velocity came in at about a megawatt per day. Not bad for 140,000 man-hours of work.      

NRG Energy
bought the site Nov. 24, and the sun juice officially began flowing into Southern California Edison’s portion of the grid Dec. 18, under the terms of a 20-year power purchase agreement. As part of the deal, First Solar has a long-term arrangement with NRG to handle the operations and maintenance chores at the plant.

But don’t expect to find a large team of operators and maintainers at the Blythe site.  A trailer houses the onsite team, led by First Solar’s plant supervisor, Allen Krawcheck. Actually, the power generation industry veteran who used to build nuclear plants is the only member of the solar company’s onsite team who’s there on a daily basis.

Krawcheck was my tour guide in early April when I came to check out the massive PV installation on my drive back from Phoenix. The weather was mild and warm that day, with a thin layer of high clouds mingled with the vast desert sky blue. When not driving or walking among the ground-mounted arrays of thin, black cadmium-telluride panels, he spends his time at work in the air-conditioned trailer that houses the command center for the operation.

We drove out to the southeast corner of the 200-acre site, where the view--with one of the many stark mountain ranges as backdrop--was spectacular. Looking out over the 350,000-odd modules, tilting three-deep on their tables at 25 degrees toward the south, the layout of the solar farm became more apparent.

Divided into 21 arrays of 1MW (AC) each(or 1.2MW [DC]), which are then subdivided into 4 250KW blocks, each megawatt array includes sturdy, shack-like structures known as power conversion stations (PCS), each of which houses a pair of 500KW Siemens inverters inside its thoroughly HVACed confines.

Nestled next to each numbered PCS is a 1MW, 34.5KV transformer that sends the array’s juice back through one of four feeder lines to the main combining switchgear. If you know where to look, you can find eight DC combiner boxes interspersed among the racks and mounts in each 1MW plot. 

If one were to go back and forth along each row of modules around the entire project, Krawcheck  estimates the distance at 95 miles—a roadtrip he will soon have to make as the time approaches for the annual, personal inspection of each and every module in the yard. So far, he explained, six or seven modules have had to be replaced, and he expects that number to rise by another half-dozen or so once he completes his inspection.

Like every First Solar module, the Blythe panels can each be tracked back to the specific production runs that birthed them, in case the FA work calls for a root-cause analysis of what might have gone off-spec in the manufacturing process (a rare occurrence in the company’s high-yielding fabs).

He couldn’t be sure whether the problems with the panels occurred as a result of construction or quality issues, although the inspection after next may reveal more clarity on the range of failure mechanisms at work. But a failure rate of 0.0034%, or one module out of every 29,166 (calculated assuming a dozen failed modules out of 350,000), is not likely to raise any red flags.

Tucked inside the control trailer are sets of computer monitors filled with displays of the site monitoring system. The set-up can “see” how well each and every part of the plant is performing in real time, setting off alarms if there’s a module string outage or something else creeping outside normal parameters. There are also data streaming from the two meteorological stations positioned in the solar field and measurements coming from an instrumented module positioned near PCS 5 (seen at left).

At the end of our tour through the arrays, Krawcheck let me have a real-time peek at how the plant was performing. Pretty darn well, as it turned out.

The power output actually registered 21.93MW and had reached 22MW earlier in the day—an amount that the site super has seen go as high as 23MW during the first few months of operation. That amount converted to an average of 1204W/m2 among the 250,000m2 of PV glass, well above the 1000W rating. A glance at the inverter performance monitors revealed many of them working in classic overachieving form—at 110%.

Krawchuck thinks that the plant will perform at its peak in May, when the longer days bring more sun to bear but the temperatures will not have risen to the torrid summertime levels associated with the U.S. southwest.  

One of my companions on the power plant tour, First Solar’s director of investor relations, Pamela Hegerty, told me that the company has a new network operations center (as in “don’t NOC it”) at its Tempe, AZ, headquarters. The center’s technicians monitor not only what’s going on at Blythe, but also at two other plants where the company has O&M responsibilities: Sarnia 1 in Ontario and El Dorado in Nevada.

By year’s end, she noted that they will also have their eyes on the second of two Sarnias (at a combined 80MW, the duo will become the largest North American PV plant of any kind) and 48MW of additional CdTe panels that will come online in Boulder City, NV, adjacent to the existing 10MW facility.   

Krawcheck, who was a supervisor at the Indian Point nuke plant in Westchester County, NY, really loves the peace and quiet of the solar farm, marveling at how what once was abandoned agricultural land became a working solar power plant within a matter of months. Other than the mild racket kicked up by the inverters and support gear in the PCS huts, there are, as he put it, “no moving parts”—something not to be discounted in an area where gale-force winds can kick up a hellacious amount of desert sand. Inadvertently waxing PV poetic, he recounted how each morning, as soon as the sun pokes over the mountains, he hears the inverters start to wake up.

Apart from the romanticized notions of solar power elicited by a visit to a site as serenely impressive as the Blythe plant, a detour on my drive from Phoenix reminded me just how far solar has to go to be truly considered “utility scale” on a magnitude with other, more conventional forms of energy generation.

Some 45 miles west of central Phoenix, several miles to the south of the interstate near Wintersburg, AZ,  sits the Palo Verde nuclear generating station, the largest power plant of its kind in the United States. Its three independent reactors can generate a total of approximately 3.7GW of electricity, some of which (15.8%) is fed to Blythe’s customer, SoCal Edison.

Construction of Palo Verde took well over a decade in the 1970s and ‘80s, a velocity equivalent to hundreds of megawatts per year—something well within reach of a company like First Solar that has proven it can install a meg a day and has made huge strides in increasing its own construction speed. Permitting and other red-tinged paperwork takes up an annoyingly inordinate amount of the project development timeline (it was 103 weeks in the case of Blythe and who knows how long in the case of any new nuke plant).

The size of Blythe may pale in comparison to Palo Verde, yet it’s not hard to imagine the scaleability—and bankability—of future PV power projects that can be engineered and built much faster than the speed of nuke. Within a few years, the first triple-digit megawatt solar PV farms will come online, and with them, the true promise of solar utilities may start to live up to the hype. 

In a future blog, I’ll talk with Tom Doyle, NRG Energy’s solar chief, about his thoughts on the Blythe plant as well as the company’s other solar plans.   

(Some of the information in this blog came from a First Solar presentation called “Anatomy of a Successful Photovoltaic Power Plant,” delivered at the Arizona Solar Manufacturing Symposium in late January. Thanks to First Solar’s Melanie Friedman for providing a copy.) 

ALL PHOTOS AND TREATMENTS BY TOM CHEYNEY

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