Solar Builder

SEP-OCT 2017

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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tracking requires about one centimeter of movement. "Our goal in these recent experiments was to demon- strate the technical feasibility of such a system," says Giebink. "We put together a prototype with a single microcell and a pair of lenses that concentrated sunlight more than 600 times, took it outdoors and had it auto- matically track the sun over the course of an entire day." The researchers report that the CPV system reached 30 percent efficiency, in contrast to the 17 percent effi- ciency of the silicon cell. All together over the entire day, the CPV system produced 54 percent more energy than the silicon and could have reached 73 percent if micro- cell heating from the intense sunlight were avoided. But (there is always a but) Giebink noted that major challenges still lie ahead in scaling the system to larger areas and proving that it can operate reliably over the long term. Insert sad emoji here. While we wait for those new markets to scale and develop, there are a bunch of intriguing options that could boost efficiencies and bridge the gap. PRODUCTION DISRUPTION Rayton Solar wants to supplant the very way we cut silicon in the first place — a technique that hasn't changed much since its inception in the 1950s. Cutting sil- icon with a diamond saw leads to a significant amount of sawdust because the process wasn't originally concerned with reducing waste for large-scale production. "We developed a process using ion implanta- tion to cut our very thin pieces of silicon, and there is zero sawdust in the process, so it allows us to increase the yield of the raw silicon and get a 60 percent reduction in the cost to make a solar panel," says Rayton Solar CEO Andrew Yakub. Phoenix Nuclear Labs (PNL) has signed a long-term agreement to be the exclusive supplier of high-current proton accelerators to Rayton Solar to produce low cost, high efficiency solar panels. Under the terms of the agreement, PNL will deliver the first system to Rayton at the end of 2017, followed by several addi- tional units in 2018 and 2019. The Rayton process utilizes high current ion beams produced by the PNL technology to cleave thin layers of silicon with zero waste. The process uses 50-100 times less silicon than the traditional method. Because of this, Rayton can also use a higher quality silicon that is about 10 times as expensive. "We are capable of making up to 100 times as many solar panels with the same amount of silicon that our competitors use to make just one panel," Yakub says. In a less radical direction, mono passivated emitter rear cells (PERC) have efficiency seekers excited, and advancements keep happening every day. Silicor Materials says that, in its first ever attempt, it has pro- duced p-type mono PERC cells at approximately 20 percent efficiency, using 100 percent of its standard silicon feedstock. Silicor hopes its technology for manufacturing solar grade silicon provides the solar market with a simple solution to manufacturing the highest quality, highest efficiency solar cells of the future at a substantially lower cost than all other solar grade silicon manufacturing technologies on the market. Sol Voltaics has taken a big step toward commercializing a new effi- ciency-boosting solar technology. Using its proprietary Aerotaxy process to manufacture PV nanowires, its SolFilm solution could boost solar module per- formance up to 50 percent at a low cost. SolFilm consists of billions of gallium arsenide (GaAs) nanow- ires oriented facing the sun. The nanowires, each of which is a com- plete solar cell, convert high-energy sun- light directly into power. Gallium arsenide, previously seen in space and concentrated solar projects, has long held great potential for the mainstream solar industry, but its high fabrication costs have prevented economical fabrication of large solar panels. Manufacturing nanowires with Aerotaxy dra- matically reduces the required amount of GaAs and removes the need for a crystalline support wafer, sig- nificantly lowering material costs. "The nanowires are grown such that the top and bottom of the wire have opposite doping profiles. This makes each nanowire a fully functional solar cell, with a pn junction along the length of the wire," states Erik Smith, CEO of Sol Voltaics. "Whether used by mod- ule manufacturers as a single-junction, high-efficiency, low-cost solution or as a boosting technology, we believe SolFilm will usher in a new age of solar power efficiencies." Sol Voltaics just closed a record funding round of $21.3 million (following a $17 million investment last year). The new funding will be used to accelerate com- mercialization of the technology. 24 S E P T E M B E R / O C TO B E R 2 0 1 7

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