POLYMER BASED LUMINESCENT SOLAR CONCENTRATORS

N.N.Barashkov, prof., Micro-Tracers Inc., San Francisco, CA;
T.V.Sakhno, prof.; V.V.Samofalov, PUET, Poltava;
I.S.Irgibaeva, prof., Eurasian National University, Kazakhstan


POLYMER BASED LUMINESCENT SOLAR CONCENTRATORS

Considering the great density of solar radiation energy flux (1.353 kW m-2 in the plane perpendicular to solar rays) which falls on the Earth at all times [1], the high level of interest to the problem of conversion of solar radiation into other convenient types of energy becomes understandable. The high cost of this conversion, however, slows down the advancement of solar energy engineering. In order to make the conversion of solar radiation into electricity, for instance, more economical is necessary to apply new cheap materials, and technical devices based on them, and to improve the efficiency of such a conversion.
The luminescent solar concentrator (LSC) represents one such device [2]. Commonly used in solar energy engineering are mirror or mirror-lens concentrators. The major advantages of LSCs is that a solar ‘tracking’ system is not needed, and they intensify both direct and diffuse solar light, whereas conventional concentrators are inefficient in collecting scattered radiation.
The first paper [3] devoted to the application of luminescence for the concentration of solar radiation was published in 1976. As a transparent medium, use was made of glass activated by trivalent neodymium ions absorbing in the spectral region from 500 to 900 nm and emitting with a maximum at 1050 nm with a quantum yield of 50-75%. Then the basic requirement was specified for the spectral overlap of the absorption and emission curves to be minimal. For the concentration of solar energy, the suggestion was made of using mixtures of dyes with different absorption and emission regions.



Figure 1 – Cut-away view of a fluorescent solar collector, lustrating its primary mechanisms: 1- light absorption, 2- light emission, 3 light propagation and conversion of light into electricity. The optical gain of this device is defined as the ratio