Solar Builder

SEP-OCT 2018

Solar Builder focuses on the installation/construction of solar PV systems. We cover the latest PV technology (modules, mounting, inverters, storage, BOS) and equip installers/contractors with tips and tools to make informed purchasing decisions.

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SOLARBUILDERMAG.COM | 39 Multiple approaches The splashiest of these partnerships is Spain-based single-axis tracking supplier Soltec teaming with the National Renewable Energy Labs (NREL), Black and Veatch and RETC to build BiTEC, the world's first evaluation center spe- cialized in bifacial trackers, in Livermore, Calif. We visited the facility in July, and the site has a variety of configurations structured to isolate and measure any site or system design effect, such as: Albedo Terrain surface Types of bifacial technology (from Hanwha-QCells, Jinko, Canadian Solar, LG and more) GCR Pitch String design 2x modules in portrait versus 1x. One variable not changed throughout the field is tracker height, with all 2x configurations standing at 7.71 ft (with 1x configuration trackers at a height of 4.43 ft). The reason is Soltec's prelimi- nary electric performance measures over bifacial modules reveal a short-circuit current difference of over 2.3 percent between 1x and 2x trackers, meaning that height has a significant influence over the energy output of bifacial panels. The capture of diffuse irradiance below and around the tracker is increased with height, while the shadow cast on the ground is softened. Array Technologies is taking a differ- ent approach. Also working with a U.S. national laboratory, Array is mapping the backside irradiance at a half cell resolu- tion as well as testing various configura- tions at string level. Array's testing is focused primarily on the module tracker interaction, varying module mounting techniques as well as testing module W e are on the verge of the bifacial solar tracker era. Projects are being quoted with many starting to break ground later this year and early 2019. Only two issues remain in the way of serious wide-spread adoption. First is the price of bifacial modules, which sits at about 30 cents a watt on average right now. The premium price makes sense because the market hasn't formed yet, and it won't form until there are bankable production estimates for the technology. That would be issue No. 2: the data set for bifacial tracker performance is incomplete, but this is about to change in a hurry. Several big-time partnerships between tracker companies, module companies and PV research and testing labs have formed within the last year to understand this new bifacial module + PV tracker paradigm, test theories and build a complete data set on bifacial tracker production. "This is a fundamentally different paradigm than before because the tracker and module are all intertwined with the site conditions in a way they weren't before," says Ron Corio, founder and CIO of Array Technologies.

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