Unisolar approves transformerless inverters from Sputnik Engineering for its thin-film modules

Unisolar has officially approved transformerless inverters from Sputnik Engineering for use with its products. With immediate effect, all amorphous thin-film modules from Unisolar – both branded and OEM products – can be combined with SolarMax products from Swiss inverter manufacturer Sputnik Engineering without further approval procedures.

The question of whether transformerless inverters are suitable for combination with thin-film modules has long been the subject of discussion. In addition, solar modules made from amorphous silicon tend to degrade over the first few months, with output and voltage initially increasing. The system must be designed in such a way as to ensure that the increased initial voltage does not damage the inverter.

Sputnik Engineering AG has been able to evaluate the effect of this voltage increase using its MaxDesign system visualisation software. The software offers the option of calculating limit values with stabilised end values or initial voltages.

"Transformerless inverters from Sputnik Engineering AG have been operating successfully with Unisolar’s amorphous silicon modules since 2005," reports Stefan Burri, Sputnik’s Head of Technical Sales Support. However, installers have until now had to combine the products at their own risk as Unisolar had not officially approved this practice. "Their official approval offers clarity and safety," adds Burri. Galvanically-separated central inverters from Sputnik Engineering AG have been approved for use with Unisolar modules for several years.

Sputnik Engineering AG focuses on the development, sales and maintenance of inverters for grid-connected PV systems.