Smart power: Caltech rolls lucky seven with new solar PV power systems

PASADENA, CA—While the VIP-laden groundbreaking on the humongous Ivanpah concentrated solar thermal power tower-based project was taking place deep in the Mojave Desert, a more modest, photovoltaically inclined dedication celebration was held under the shade of a framework-style array on the top deck of a parking structure at the California Institute of Technology campus. BrightSource’s 392MW CSP mega-plant may generate a serious amount of centralized-generation solar electricity for the grid when/if it comes online in a few years, but Caltech’s seven separate rooftop systems—totaling 1.176MW (DC) in distributed-generation capacity—have been grabbing photons since late September.

 The septet of installations range in size from 26.88KW and 40.32KW systems on the respective roofs of the Cahill Center and Infrared Processing and Analysis Center (IPAC) to 379.68KW and 440.16KW canopies gracing the tops of the two Wilson parking structures. Together with the previously installed 265KW of PV, the new systems will provide approximately 2% of Caltech’s energy consumption, according to John Onderdonk, the school’s sustainability manager.

Two flavors of Suntech crystalline silicon, 210W and 280W, comprise the 4624 modules deployed (with the more powerful panels designated for the largest arrays), with Advanced Energy and SMA inverters handling the power conversion duties. The main components of the custom-designed, steel space-frame arrays were fabricated by Uskon in Turkey. A Lucid Design monitoring system is being implemented, replacing the Fat Spaniel software used previously.

In addition to the Caltech facilities and sustainability program teams, the project was led by developer/power purchase agreement provider Perpetual Energy and Suntech, which subcontracted the engineering, procurement, and construction duties to its partner, Swinerton Builders’ renewables unit.

Perpetual, which owns and operates the new system, has a 20-year PPA with Caltech. The company has used its financing prowess to “work together very closely with different financial partners that bring together capital or equity into the project,” explained Joseph Rodriguez, president of the development firm. “We bring our own equity, our own capital, and we leverage that with tax equity from tax investors.”

“So the end-product is a system that we own, together with a tax equity investor,” he continued. “They’re there for a short time and we end up with 100% of the equity, and we’re able to put together the financing package to the host. So there’s really no capital outlay behind it, it’s a relatively complex financial structure that’s something we’re able to put together efficiently and relatively quickly as well.”

Jim Irwin, Caltech’s senior director of facilities management, cited “avoided cost” as one of the main advantages of the deal. “We’re purchasing electricity at a better price than we can purchase it from the municipality. Over the period of the contract, it’s a financial benefit to us and an avoided cost from what we have to purchase.”

A smiling Mauricio Mejia of Pasadena Water and Power explained the local utility’s role in the project in no uncertain terms. “We’re the people that bring the money to make this project a reality. Solar incentives normally cover about a third of the cost. I think most of the people here would agree that without those incentives, either from the federal government or the local municipalities or the local utility, this project would probably never be completed.”

“We have in Pasadena, through our local utility, rebates for our commercial customers. The total money that Caltech will receive for all the installations will be close to $6.5 million that they will receive in five installments over the years. The rebate is based on the amount of electricity that a system like this one here would generate. We’re not just giving a rebate for the number of modules that get installed. We actually measure the amount of power the system generates, and we’ll give them a rebate based on that,” he added.

Construction on the initial system—the 64KW installation on top of the Annenberg Center for Information Science and Technology—began in February, with the larger subprojects commencing in late March, according to Dave Cramp, project manager for Swinerton.

There are some subtle differences between Caltech’s first major PV project, a 200KW parking structure system on top of the Holliston parking structure completed in November 2008, and the pair of new large installations, according to Cramp. One aspect is the way the “the space frame goes together with screws, while the other one was hammered. This one is quieter and little simpler, but there’s a little less room for forgiveness.”

“This one is a lot bigger, with more square footage covered,” he continued. “At the bottom [of the framework poles], where they connect to the concrete columns, we have anchor bolts directly in, so they had to be exact. Over there, they were welded at the end, so there was a lot more room for forgiveness.”

Andrew Beebe, now chief commercial officer for Suntech, came to his current employer when his former company and contractor on the initial Caltech project, EI Solutions, was acquired. “It’s basically the same panels, so there’s not much you can change, though they’ve run the wires in a slightly different way.” Pointing toward the underside of the overhead array, he noted that the “conduit is probably a little bit more bulletproof than what was used previously.”

[CORRECTED] I asked George Hershman, VP and division manager of Swinerton's renewable energy unit, if he’s seeing a trend toward preassembly or prefabrication of PV systems, any movement toward more modularity and reduced field assembly. (NOTE: Original version misattributed following quotes to Hershman's colleague, Dave Cramp.)

“It’s on a case-by-case basis,” he said. “There are some projects that make a lot of sense to do some prefabrication, some rooftop systems that work well that way. We’re finding in these types of projects, in campus environments and things like that, where operating a crane continuously is not available to us, we can load one day during the weekend when the campus is not occupied. That doesn’t allow us to do a lot of prefabrication, so we have to load during a Saturday and a Sunday so that we can work during the week.

“We don’t have a one-size-fits all approach, we try to look at each project and say, what’s the best way to execute that work. Different systems allow for different levels of prefabrication, different areas, locations for labor, different labor agreements, different ways we can look for cost effectiveness on a job where we might implement those types of things.”

“I think that’s where a company like ours, being part of a $2 billion a year general construction company, that is not a solar-only company, pulls those expertise from all of our different lines of work,” Hershman noted. "We’ve got the same superintendents and project managers that are building structures looking at these projects. We look at them in a little bit of a different approach than perhaps a solar-only company that says this is the way that we have scaled these projects: we look at them as a kit of parts."

School president Jean-Lou Chameau told the audience during the ceremony that the combined solar installations—now at over 1.44MW, including the 200KW array on the Holliston parking structure activated in November 2008 and a couple of smaller systems—represent the largest PV facility in the city of Pasadena and the eighth-largest

Given Caltech’s undersized student body (900 undergrads, 1200 grads), I wonder if it might actually have the largest per-capita photovoltaic capacity of any institution of higher learning in the States, since wellsolar-endowed schools like Arizona State and Colorado State boast enrollments into the tens of thousands. As measured by the size of the combined systems divided by the number of students at the institute, that number is roughly 686W per (propeller) head.

The installed capacity per Nobel Prize winner among the faculty is also quite impressive: 45KW for each of the 32 laureates. Now that’s what I call smart power.

PHOTOS BY TOM CHEYNEY

http://www.pv-tech.org/lib/printable/11833/ Published: 28 October 2010 All contents © copyright 1994-2010 Semiconductor Media Limited.