PHOTON International The Photovoltaic Magazine

On-grid inverter from Solarstocc a competitive alternative to Kyocera

German wholesaler Solarstocc AG and major Japanese PV company's European subsidiary Kyocera Fineceramics GmbH have two things in common: both introduced their first inverter series with nominal powers of up to 4.5 kW in Germany earlier this year, and both companies apparently trusted the same manufacturers with the development and production of their inverters.

© Solarstocc AG

A glimpse inside reveals everything: The new inverters from Solarstocc and Kyocera have an identical construction (pictured here, the PS 6000).

After Kyocera presented its grid-tied string inverter in March at the Staffelstein PV Symposium (see PI 5/2004, p. 30), Solarstocc introduced its Powerstocc series at Intersolar in Freiburg in June. But one look inside the devices reveals all: the inverters' hardware is identical in construction. Like Kyocera's inverter, the Solarstocc inverters have an integrated high-performance transistor module. They combine several power transistors in a single housing and are intended to ensure an optimal heat control within the device, thereby guaranteeing a higher efficiency.

Moreover, both types of inverters have a module construction with several direct voltage inputs, each of which has its own power module with independent MPP tracker. Hence, depending on inverter power, between one and three solar generators can be operated with one device, all of which can be designed, aligned, and shadowed differently. Alternatively, the inverters can operate in an internal master-slave mode. Depending on the intensity of the sun, between one and three power modules go into action, which has a positive effect on efficiency.

The Powerstocc inverters come with a number of different power module types. Whereas the High-Voltage version (HV, see table) is designed for solar panels with 5 inch cell technology, the Medium Voltage version (MV) is best suited for 6 inch cells. The PS 4000, PS 5000, and PS 6000 even can have two different power modules. Next year, Solarstocc will begin offering a third power module version, which is optimized for stand-alone systems.

The Powerstocc devices' modular construction allows for efficient system planning. If one wants to start with a small PV system, but expand later, one can use a "large" inverter, which at first employs only one power module. Additional power modules then can be added at a later date. The advantage: one large inverter is less expensive than two smaller ones.

Naturally, the devices from Solarstocc and Kyocera differ with regards to design of casing and color. Other differences are apparent in the model power range and the software. Whereas there are three Kyocera inverters for indoor application with nominal powers between 1.5 and 4.5 kW, Solarstocc offers five inverters with power ratings between 750 W and 4.5 kW.

Until now, Solarstocc has dealt almost exclusively with SMA inverters, but "already last year, it was apparent that the supply of inverters was becoming scarce. So, we wanted to adjust for that," explains Hans-Bernhard Schmohl, technological director at Solarstocc, about the company's strategy to introduce its own product. The indoor devices from Solarstocc and Kyocera have been available since July. By August or September, Solarstocc intends to release its outdoor devices. Solarstocc's inverters are currently available in Germany, Luxembourg, and Greece; export to France, Austria, and Holland is targeted for next year. auchdie Outdoor-Geräte anbietenauf den Markt bringen. Preise wurden nicht genanntkeine bekannt gegeben.

datasheet

Solarstocc AG
Karlsberger Strasse 3
87471 Durach, Allgäu, Germany
phone +49/831/540214-0, fax -5
info@solarstocc.com
www.solarstocc.com