Holographic Optical Elements (HOEs) offer precise manipulation of light wave direction, focus color separation and polarization. While often described as a microns thin lens, HOEs operate in ways that cannot be matched by conventional lenses, mirrors or Fresnel optics. Thinner than paper, HOEs are able to operate on all waves in the light spectrum, including infrared and ultraviolet.
Currently, HOEs are being employed in optoelectronics for optical memory discs, Diode Lasers, gun sights and in many other applications. In the case of Diode lasers, HOE focusing elements are used to correct the laser’s large angle of divergence, improving the beam’s focus and effectiveness.
Solar PV glass is an ideal application for HOE technology. Because traditional solar technology consists of simply placing a solar panel in the direct path of sunlight and passively gathering what the sun radiates, there are inevitable losses as natural elements of light direction, refraction and surface reflection adversely affect efficient solar energy transfer to the cells. The HOE corrects, selects, optimizes and directs the collected light wave elements to the solar cell, thereby allowing more energy from all components of sunlight to be directed to the solar cell and converted to electricity.
The proposed product is a glass sheet for solar panels which incorporates an optically clear Holographic Optical Element (HOE) layer applied to the glass. The HOE enabled glass redirects the direction angle of the incoming rays of sunlight to Brewster’s Angle, which is the optimal angle for light transfer to the solar cell. A cell, receiving light at Brewster’s Angle, will generate the maximum amount of electrical output possible for that cell with maximum efficiency.
“Brewster's Angle” is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent surface, with no reflection. This special angle of incidence is named after the Scottish physicist Sir David Brewster (1781–1868). Source: Wikipedia”
Published research by Dr. Christer Watson of Manchester University confirms that Brewster’s Angle is the optimal angle of delivery of light passing through glass. But, consistent achievement of this ideal angle means that a polarizing element needs to be applied to the glass.
Based on the findings of Dr. Watson’s experiments, published as “Determination of Brewster’s Angle for Glass and Plastic using a Polarized Monochromatic Light Source” it is estimated that by maintaining Brewster’s Angle through the use of a HOE layer, light wave delivery through glass to a solar cell can be increased by up to 25% more over conventional solar glass.