The challenge

When biaxial tracked, a mirrored parabolic dish concentrates the solar radiation on one single spot that shows an unequal distribution of light intensity. The arrangement of multi-junction PV cells in this single spot imposes difficulties concerning an equal exposure to radiation as well as the installation of electrical wiring and a cooling circuit. How can solar radiation be equally distributed on a multitude of new focal points surrounding the first focal point of the parabolic dish?

The invention

The RES-Two-Step Dish Collector uses a spherical lens to distribute the concentrated radiation on e.g. six new focal points within a parabolic dish. While the centre of the spherical lens matches the focal point of the parabolic dish, the inner surface of the spherical lens consists of six facets surrounding a hollow space. The concentrated radiation will be refracted at each facet to create six new focal points around the first focal point of the parabolic dish. Thus space is created for the multi-junction PV cells including electric wiring and a cooling system. The optical, the electrical and the photovoltaic components may be encapsuled in an evacuated glass container to protect them against environmental impacts and pollution.

The advantages

  • Provision of a 1000-fold concentration system for multi-junction PV cells
  • High efficiency: PV >35%, thermal 45%
  • Provision of solar modules suited for industrial prefabrication
  • Protection against environmental impacts and pollution
  • Local production of the load-bearing system and the biaxial tracking devices
  • Minimal maintenance and durable components
  • The parabolic dish can be replaced by a Fresnel lense

The applications

  • Depending on their specific diameter, the modules may be designed for an electrical output of 200 W, 300 W or 500 W
  • Decentralized generation of electrical power
  • Integration of solar collectors in urban environments
  • Special application as a solar lighting system