Fronius International GmbH is an Austrian photovoltaic manufacturer based in Pettenbach, Upper Austria.

[2] Günter Fronius occupied himself with the development of battery charging systems in an electrical business.

Günter Fronius handed over the management of the business to his two children in 1980, and from then on the company focused more and more on expansion and internationalisation.

Fifty years later the company launched the CMT (cold metal transfer) process, which permits the thermal joining of steel to aluminium.

Covering an area of more than 5,000 m2,[6] it is the "centre of excellence" for Fronius welding torches and accounting & internal auditing.

One of the largest photovoltaic systems in Austria, with a module area of 3,600 m2, can be found on the roof of the building.

Thalheim, near Wels, is the research and development site of the company and was to be extended to cover 22,500 m2 by 2009.

The site, which was opened in 1990, extends over 17,000 m2 and is the starting point for the international activities of all three Fronius divisions.