This UL certification can be seen as laying the foundation for the safe and wide-spread use of transformerless inverters in the US. Due to the special requirements of American standards, up until now PV plants here were almost always designed using galvanically isolating devices. In comparison, transformerless inverters are more efficient (among other benefits), which means the operators will benefit accordingly as a result of maximum energy yield. In addition, their reduced weight will make it significantly easier for installers to mount the devices.
UL is one of the world's most renowned product safety certification organizations, and working together with SMA, developed a highly complex testing procedure for transformerless inverters. In addition to other things, monitoring residual currents and ground faults were integrated, which means maximum safety for the user. As a result, the UL 1741 Standard of Safety was expanded accordingly to include the requirements of the IEC 62109 Standard. In contrast to string inverters offered by other manufacturers, SMA's certified inverters also have an attractive price-performance ratio and above-average efficiency of up to 98 percent according to the California Energy Commission (CEC). "Thanks to the OptiTrac MPP tracking procedure, which is patented in the US, and the OptiCool active cooling system, we ensure that our inverters have above-average efficiency – even when used in areas with high ambient temperatures above 45 degrees Celsius (113 degrees Fahrenheit). Which means we are way ahead of other manufacturers from a technological standpoint," says Bernd Engel, Senior Vice President Technology and Development.
The first UL certification for transformerless inverters is not just significant for SMA, but also for the entire North American market. "For the first time, SMA highly efficient transformerless inverters can be used in the US. This means both a reduction of system costs and leap ahead technologically. In addition, the Sunny Boy 10000TL-US was developed based on SMA transformerless Sunny Mini Central, which in the meantime is now the best-selling and as a result, most successful inverter worldwide," says Engel. Ultimately, the close cooperation between SMA and the certification organization UL, which SMA has worked with for many years, is crucial to its success. "These projects are characterized by their transparent dialog between experts from both companies, and experiences are shared in an open and honest manner. Doing so offers the best conditions from which to design demanding testing procedures and high-quality inverters." In reality, it is difficult for products which have not received UL certification to be successful in the US market. In addition, according to Engel, UL certification is not only in demand in the US, but in Canada as well. "In light of this fact, certifying our transformerless US inverters also represents a further milestone in expanding our leading position in the market," concludes Engel. SMA certified inverters, which can be finely adjusted from 8 to 10 kW, are especially suited to use in PV plants from the medium power range to the megawatt class, and are shipped with a DC disconnector as well as a Combiner Box.
With a turnover of 934 million Euros in 2009, the SMA Group is the global leader in the market for solar inverters, which are a central component of every solar power system. The SMA Group is headquartered in Niestetal, near Kassel in Germany. It is represented by international subsidiaries on four continents. The entire group has more than 5,000 employees (including temporary workers). SMA produces a broad range of inverter types, the suitable inverter for every type of photovoltaic module, and offers inverters for photovoltaic plants of all sizes. The product range includes inverters both for grid-connected photovoltaic systems and for stand-alone systems. The parent company SMA Solar Technology AG has been traded in the Prime Standard on the Frankfurt Stock Exchange (S92) and has been part of the German TecDAX stock index since 2008. SMA has received numerous awards in recent years as a result of the company's outstanding performance as an employer.
Underwriters Laboratories® is an independent product safety certification organization that has been testing products and writing standards for safety for more than a century. UL evaluates more than 19,000 types of products, components, materials, and systems annually with 20 billion UL Marks appearing on 66,000 manufacturers' products each year. UL's worldwide family of companies and network of service providers includes 68 laboratory, testing, and certification facilities serving customers in 102 countries.
SMA Solar Technology AG
34266 Niestetal, Germany
Tel. +49 561 9522-2805
Fax +49 561 9522- 4567
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