Sonne am wolkenlosen Himmel


A ray of light for the solar industry

Solar energy made great strides in the 1970s with the development of fluorescent collectors. These were the brainchild of physicist Adolf Goetzberger.

Sunny days: in 2018, solar power systems in Germany generated more than 46 billion kilowatt hours of solar power, according to the German Solar Industry Association, enough to cover the annual electricity demand of around 13 million households. These figures are partly thanks to the work and dedication of Adolf Goetzberger.

In the first 25 years of his professional life, the physicist devoted himself to semiconductor technology, where he worked with, among others, Nobel Prize winner and co-inventor of the transistor  William Shockley and at Bell Laboratories in the USA. In the late 1960s, he began to turn his attention to solar energy. At that time, few were talking about generating energy through alternative means like solar technology. Adolf Goetzberger conducted extensive research in the field of fluorescent collectors. His basic idea: sunlight can be collected by large panels and in these converted by a fluorescent dye. Total reflection guides the converted sunlight to solar cells at the edge of the panel. If the edge area is smaller than the surface of the panel, the light can be concentrated. This requires fewer expensive solar cells than if the entire surface were covered.

Greater efficiency thanks to fluorescent collectors

Adolf Goetzberger’s idea would go on to improve efficiency in solar power generation significantly. The researcher patented his idea for fluorescent collectors in 1976. Five years later, he founded the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg. With Adolf Goetzberger at the helm, the ISE developed the first highly efficient electronic inverter for autonomous photovoltaic systems and took the first steps towards highly efficient silicon solar cells, III-V semiconductor solar cells, thin-film solar cells, and solar silicon. Today, the ISE is one of the institutions leading the way in solar research. In 2009, Adolf Goetzberger was awarded the European Patent Office’s European Inventor Award for his life's work. His book “Photovoltaic Solar Energy Generation” is still a definitive text for scientists all over the world.

(Header: Karoline Thalhofer –, Detailbild: COHAUSZ & FLORACK)

fluorescent collectors in the garden

Ort der Erfindung

Fraunhofer-Institut für Angewandte Festkörperphysik IAF, Tullastraße 72, 79108 Freiburg