Schneider Electric (schneider-electric.com) is headquartered in Rueil-Malmaison, France, and entered the electricity industry in 1891. Schneider is a multinational corporation with a long history of manufacturing electrical motors and equipment for power stations. Schneider acquired Square D, which transformed the company into the world’s largest manufacturer of electrical distribution equipment. Schneider Electric entered the solar inverter market in 2008 with the acquisition of Xantrex Technology, a well-known solar and wind inverter manufacturer in the United States offering residential and commercial products for on- and off-grid systems.
For batteryless residential inverters, Schneider Electric offers its transformer-based Conext TX, in 2.8, 3.3, 3.8, and 5 kW models, with CEC-rated efficiencies ranging from 94.5% to 96%.
SMA (sma-america.com) was founded in 1981 and is headquartered in Niestal, Germany. SMA Solar Technology provides inverters for all PV market segments. The company’s U.S. subsidiary, SMA America, was founded in 2000 and is headquartered in Rocklin, California, and has a production facility in Denver, Colorado.
SMA offers many Sunny Boy residential string inverters. Its transformer-based series includes a smaller high-frequency (HF) model in 2.0, 2.5, and 3.0 kW capacities. These units have slim profiles (14 inches wide by 29 inches tall) and are lightweight (51 pounds, including the DC disconnect box). Their CEC efficiencies range from 96.5% to 97%. Seven low-frequency (LF) transformer-based models range between 3.0 and 8.0 kW, with 95.5% or 96% CEC efficiency depending on the model.
SMA offers six transformerless (TL) models spanning 6 to 11 kW, with CEC efficiencies (at 240 VAC output) between 98% and 98.5%. The newest TL models have 3.0, 3.8, 4.0, and 5.0 kW capacities and a 96.5% CEC efficiency. These models include dual MPPT inputs and a secure power supply feature, which allows for some daylight backup power during utility outages (see “Backup Power—Without Batteries” in HP159). With the exception of the HF models, all of these Sunny Boy string inverters have integrated arc-fault protection (either as a standard or optional feature).
SolarEdge Technologies (solaredge.com) was founded in 2006 and is based in Israel, with offices in China, Germany, Italy, Japan, and Fremont, California. SolarEdge inverters are designed specifically for use with its module-level MPPT power optimizer system.
SolarEdge offers seven residential transformerless inverters, in 3 to 11.4 kW capacities. These inverters have integrated arc-fault protection and 97.5% to 98% CEC efficiency at 240 VAC output. Because they are specifically designed to be used with the power optimizer system, they have a built-in module-level monitoring receiver.
Solectria Renewables (solectria.com) is headquartered in Lawrence, Massachusetts, and was founded in 2005, and focuses on utility-interactive grid-tied PV inverters and string combiners. However, its predecessor, Solectria Corp., acquired its power stage technology in 1989. Solectria Corp. manufactured electric and hybrid vehicles, as well as power electronics and controls for high-power systems.
Solectria’s residential inverters include its PVI 1.8 and 2.5 kW transformer-based models, which have a NEMA 4X rating and a 92.5% and 93% CEC rating, respectively. Solectria’s latest residential inverter is a transformerless series including a 3.8 kW version with a single MPPT input. The 5.2, 6.6, and 7.6 kW versions with dual MPPT inputs, were projected to be available in the second quarter of 2014. All of these transformerless models have a 97.5% CEC efficiency and are slated to offer optional DC arc-fault protection.
Justine Sanchez is a Home Power technical editor and an instructor for Solar Energy International. She is certified by ISPQ as a PV Affiliated Master Trainer. Justine is planning her next PV project—a backyard PV shade structure—and is currently considering her inverter options.