Topaz Turns on 9 Million Solar Panels

This is the world’s largest solar power plant, Topaz Solar Farms, where First Solar, based in Tempe, Ariz., has erected nearly 9 million of its cadmium-telluride thin-film photovoltaic panels across 19 square kilometers of former ranchland.  This sea of panels and the associated inverters and transformers are designed to deliver 550 megawatts of low-carbon AC power, enough to service 180,000 homes.  The site will reach its full design capacity early this year.

Topaz marks the pinnacle in a massive scale-up of grid-connected solar power across the United States.  As recently as 2009, rooftop systems accounted for nearly 90 percent of U.S. solar capacity.  While installation of rooftop PV continues to expand, utility-scale solar has come to dominate the market. This year, plants like Topaz will add more megawatts than the entire U.S. solar market did in 2013, according to projections by Boston-based green-tech consultancy GTM Research.  Indeed, First Solar is also nearing the completion of another massive PV plant, its 550-MW Desert Sunlight Solar Farm, in Southern California.
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Solar PV continues to benefit from a virtuous cycle in which new installations beget cost reductions that drive further adoption.  In the process, the price of solar-generated electricity has plummeted.  While PG&E is obligated by its 2008 agreement to pay about US $0.20/kWh for Topaz’s electricity, recent PV projects are earning just $0.05/kWh to $0.06/kWh.  The price drop reflects both mass production and technology upgrades, the latter of which is visible at Topaz.  When First Solar installed the first panels there in 2012, each was rated to produce 77.5 watts of direct current.  The last panels to be installed, by contrast, are rated for 97.5 W DC—a 26 percent increase in output—thereby cutting the per-megawatt cost of installing new capacity.

Such advances in PV technology have turned utility-scale solar into a mainstream option for utilities looking to meet midday power demand.  According to the financial firm Lazard, new grid-scale solar plants now deliver at $0.072/ kWh to $0.086/kWh when subsidies are excluded.  That stacks up well against electricity from even the most efficient natural-gas-fired plants, which costs $0.061/kWh to $0.127/kWh (with the higher end including the cost of CO2 capture).  Between June 2013 and July 2014, U.S. utilities announced plans to buy 3,000 MW of utility-scale solar power without or ahead of state mandates, according to the Solar Energy Industries Association, a Washington, D.C.–based trade group.  Bolinger says that utility-scale solar is also advancing in South America and Asia.

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