Design method for high efficiency solar concentrators and related photovoltaic application

Researchers developed a new design method and a specific concentrating photovoltaic system for high conversion efficiency, based on controlled deformations induced in standard concave mirrors. The efficiency gain is obtained without secondary optics or special electrical features in the receiver.

Title of the patent Solar concentrator and method for optimizing the distribution of irradiance
Thematic area Mechanical, civil and environmental engineering
Ownership Alma Mater Studiorum - Università di Bologna and National Institute for Astrophysics
Inventors Bruno Marano, Alessandra Giannuzzi, Giuseppe Cosentino, Giovanni Bregoli, Adriano Giuseppe De Rosa, Emiliano Diolaiti, Italo Foppiani, Matteo Lombini, Laura Schreiber
Protection International application
Licensing status Available for licensing agreement
Keywords Concentrated solar energy, solar concentrator, high concentration phototovoltaics (HCPV), non-imaging optics, illumination uniformity, irradiance profile, ray-tracing, multi-junction (MJ) solar cells, high efficiency solar cells, dense array receiver
Filed on Jan 14, 2014

Concentrating technology is a way of smartly exploiting solar energy.  Solar concentrators operate thanks to optical devices, such as lenses or mirrors, that focus and amplify the incoming solar energy flux. The development of solar modules with efficiency continuously improved at high irradiances encourages the use of optical concentration combined with photovoltaic receivers in CPV (Concentrating Photovoltaics) systems. Some of these systems (called dense array systems) use large mirrors (dish) to collect the light onto arrays of tiny photovoltaic cells (multi-junction) densely packed into a single receiver theoretically able to convert the sunlight into electricity at more than twice the efficiency of fixed flat PV panel.

When standard mirrors are coupled with dense array receivers, problems arise since the cells are not under the same illumination and the real conversion efficiency is much lower than the theoretical one. A whole dense array concentrator and a general method to design high efficiency concentrating optics has been developed. The problem of enhancing the efficiency by designing free-form mirrors that can produce sun spots with high uniformity and desired shapes was solved. The optics have been optimized and validated by a ray tracing software and the systems shows a substantial gain in efficiency without involving secondary optics.

The main field of application of the patent is the production of 100% renewable electricity and thermal power. The proposed system has been designed to work in cogeneration producing 10 KW of electricity and around 20 KW of thermal energy. The system has the advantage to be used alone for small residential applications or arranged in modular installations for utility scale plants. The design method allows to conceive and design similar systems for bigger/smaller applications and different uses. The high irradiance reachable on a relative small area and the tunability of the light spot collected by the mirrors with the receiver chosen features make this technology particularly suitable also for performing material tests and highly efficient chemical reactions for clean fuels production.