In addition to complying with UL standards, this inverter from Siemens meets international standards: DIN, VDE, IEC, EN.

The inverter’s application software and firmware are UL 1998 listed. The inverter will be certified to UL 1741, CSA 107.1 and CEC standards and features: under-over-voltage control, under-over-frequency control, open phase control, grid synchronization and anti-islanding protection, which detects and isolates the system from grid failure under matched load conditions.

“Siemens is one of the pioneers in the field of photovoltaics with more than 40 years of experience in planning, building and maintaining photovoltaic power systems for a wide array of applications,” said Richard Thomas, director, clean technology & renewable energy, Siemens “Through the introduction of our UL compliant inverter, we are reaffirming our commitment to our extensive customer base by making this proven, sustainable technology available in the North American market.”

Built in accordance with a stringent ISO 9001 quality system, the inverter has been optimized for high efficiency and has a compact design and footprint that facilitates easy installation. Architecturally, three inputs with LV HRC fuses and DC contactors are provided at the PV field end, a combination that can be used to isolate the inverter from the PV field. Additionally, the IGBT-based power unit coupled with a low-voltage transformer provides galvanic isolation between the PV field and AC output, which prevents unwanted current from traveling between units sharing a ground conductor. Additionally, it increases safety by preventing accidental current from reaching the ground. Separately, a contactor and discrete circuit breaker can be used to disconnect the unit from the grid. Overvoltage protection devices are installed at the AC output and DC inputs.

Additional new features include cluster control, optional PV array isolation measurement and optional symmetry monitoring. With the cluster control operation up to four inverters can be interconnected at a common DC bus to increase efficiency, reduce light-load losses and enhance system reliability. The PV array isolation measurement detects faults in the PV array much earlier than existing ground fault detection techniques. With the symmetry monitoring option, the current of each DC input is monitored separately and analyzed over a long time period to allow for detection of power losses due to defective PV panels.