String Inverters Single-Phase Solutions for the North American Market (2011): Page 8 of 10

This ability to leverage the backing of a 19.6B euro company— one that is also a leading supplier of electrical distribution equipment—is one of the things that sets Schneider Electric apart. Catanzaro notes: “We not only offer inverters, but also a full line of dc and ac circuit protection products and disconnects from Square D.” While the company uses a mixture of in-house and contracted manufacturing plants in Asia and North America, its new single-phase line of Conext series inverters for North America will be produced in Bangalore, India, where a subsidiary, American Power Corporation, has manufacturing plants. Catanzaro explains: “This allows the product line to take advantage of world-class manufacturing and global supply chain capabilities within the Schneider Electric group.”

The redesigned Conext series of string inverters from Schneider Electric consists of four models designed for 208 Vac or 240 Vac interconnection, ranging in capacity from 2.7 kW to 5 kW. The high-frequency, transformer-based inverters are housed in NEMA 3R enclosures. Each unit includes an integrated Square D disconnect that opens both the dc and ac inputs to the inverter. The inverters are passively cooled, which allows them to be installed side-by-side with no side clearance. The Conext series inverters feature Fast Sweep technology, a shade-tolerant MPPT algorithm. Schneider reports that performance is comparable to microinverter systems.

SMA. Founded in 1981 when it was spun off from the University of Kassel, SMA has been headquartered in Niestetal, Germany, since 1982. Since 2008, shares in SMA Solar Technology have been listed in both the Prime Standard of the Frankfurt Stock Exchange (S92) and the TecDAX. Sales of 1.9B euros were reported in 2010, making SMA the world market leader for solar inverters. The company currently employs approximately 5,000 people worldwide and has 17 foreign subsidiaries on four continents (Asia, Australia, Europe and North America), including four subsidiaries in the US and Canada. While SMA does not release subsidiary sales figures, David Wojciechowski, senior director of sales for SMA America and SMA Canada, reports: “About 80% of SMA’s 2010 global sales were generated by its medium-power solutions, which include residential and light commercial inverters.”

A longtime leader in residential inverter technology, SMA released its first solar inverter, the PV-WR, to the European market in 1990. Subsequent European product releases include a long list of industry firsts: the first highvoltage string inverter (the Sunny Boy 700) in 1995; the first transformerless inverter (the Sunny Boy 1500) in 1998; and the first multistring inverter (the Sunny Boy 5000TL) in 2002. Similarly, the first high-voltage string inverters available to the North American market were a pair of UL-listed, 60 Hz transformer-based Sunny Boy string inverters—the SWR 1800 and SWR 2500—released in 2001.

SMA currently offers 14 grid-direct string inverters in North America, many of which operate at multiple output voltages. The original 60 Hz transformer-based inverter line has been updated and expanded over the past decade; the US series of Sunny Boy inverters currently includes eight models ranging in capacity from 700 W to 8,000 W. SMA also offers a series of three high-frequency string inverters, ranging in capacity from 2 kW to 3 kW; inverters in the HF-US series are designed to fit between studs, making them ideal for new construction or space-constrained retrofit applications. In 2010, SMA introduced its TL-US series of inverters in North America; ranging in capacity from 8 kW to 10 kW, these are the first transformerless inverters ever to receive UL certification.

SMA’s annual manufacturing capacity is 11 GW, the highest of all solar inverter manufacturers; this includes 500 MW of capacity in Ontario, Canada, and 1 GW in Denver, Colorado, which is reportedly the western hemisphere’s largest inverter assembly site. ARRA-compliant string inverter models being assembled in Denver include SB 3000-US, SB 4000-US, SB 5000-US, SB 6000-US, SB 7000-US and SB 8000-US. These same Sunny Boy models are also being assembled in Ontario, initially by Celestica, to meet the province’s microFIT requirements for domestic content.

According to Wojciechowski, SMA’s commitment to regional production sites is just one of the strategies that the company employs in order to protect its leadership position in the North American market. The other way is through continued innovation of its products and technology. “SMA’s Sunny Boy TL-US series of transformerless inverters offers significant improvement in a range of key criteria when compared to traditional galvanically isolated PV inverters,” he explains. “Eliminating the transformer has allowed SMA to improve the efficiency of the system and, therefore, energy yields. At the same time, weight has been reduced by nearly half, allowing for easier installation. Integrators have been quick to recognize the benefits of transformerless inverters and have rapidly adopted these new models for their projects.”

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