Fluorescent concentrators

Fluoreszenzkonzentratoren mit unterschiedlichen Farbstoffen
© Fraunhofer ISE
Fluorescent concentrators in different colors.
© Fraunhofer ISE
Fluorescent concentrators are available in many different colors.

Fluorescent concentrators, also called luminescent solar concentrators, are capable of concentrating both diffuse and direct sunlight without the need for tracking systems. Concentrating the light in this way means that only a smaller solar cell surface area is required, bringing down costs.This quality makes them an ideal concentrating technology for use in middle latitudes, in countries such as Germany that do not enjoy large amounts of direct insolation. Being just as flat as conventional modules, they can also be integrated without problems both onto and into buildings. Even windows that generate power are conceivable with this technology.

Fluorescent concentrators are available in many different colors, making them appealing for all applications where aesthetics are just as important as power production.
In a fluorescent collector, dyes or other luminescent materials configured in a transparent matrix absorb the incident light. The light is subsequently re-emitted in all directions at a longer wavelength. Owing to the difference in the refractive index, a large proportion of the emitted light is trapped by total internal reflection at the interface between the collector and the external environment, and is thus guided to the edges of the collector where solar cells convert it into electrical energy.

Our current investigations center specifically on fluorescent concentrators that are active in the infrared spectrum and on how their efficiency can be improved using photonic structures. Fraunhofer ISE has a comprehensive range of methods at its disposal for characterizing source materials as well as for implementing and characterizing entire systems. The theoretical description and simulation of fluorescent concentrators also form part of our work in this field.