Hybrid Trough solar power system using photovoltaic two-stage light concentration
A solar power method is provided using two-stage light concentration to drive concentrating photovoltaic conversion in conjunction with thermal collection. The method concentrates light rays received in a plurality of transverse planes towards a primary linear focus in an axial plane, which is orthogonal to the transverse planes. T band wavelengths of light are transmitted to the primary linear focus. R band wavelengths of light are reflected towards a secondary linear focus in the axial plane, which is parallel to the primary linear focus. The light received at the primary linear focus is translated into thermal energy. The light received at the secondary linear focus is focused by optical elements along a plurality of tertiary linear foci, which are orthogonal to the axial plane. The focused light in each tertiary primary focus is focused into a plurality of receiving areas, and translated into electrical energy.
1. A hybrid trough solar power system using two-stage light concentration to drive concentrating photovoltaic (CPV) conversion in conjunction with a thermal collector, the system comprising:
a reflective trough having a primary axis and a parabolic curved surface for concentrating light rays received in a plurality of transverse planes into a primary linear focus in an axial plane, orthogonal to the transverse planes;
a dichroic spectrum splitter having a hyperbolically curved surface, an axis aligned in parallel to the primary linear focus, and a position between the reflective trough and the primary linear focus, the dichroic spectrum splitter transmitting T band wavelengths of light, and reflecting R band wavelengths of light to a secondary linear focus formed parallel to a vertex of the reflective trough in the axial plane;
a thermal collection tube aligned along the primary linear focus for the T band wavelengths of light;
a plurality of concentrating optics sections formed in series along the secondary linear focus, each concentrating optics section comprising
an imaging optical element focusing the R band wavelengths of light reflected by the dichroic spectrum splitter along a tertiary linear focus orthogonal to the axial plane,
a plurality of optical funnels aligned serially in a row along the tertiary linear focus of the imaging optical element, the plurality of optical funnels concentrating the R band wavelengths of light focused by the imaging optical element to a plurality of receiving areas
and for each optical funnel, a PV device having an optical interface formed at a corresponding receiving area of the plurality of receiving areas;
wherein each concentrating optics section is independently rotatable about a corresponding local axis, and each local axis is orthogonal to the axial plane; and,
wherein the orthogonality of each imaging optical element to the reflected R band wavelengths of light is responsive to the rotation of a corresponding concentrating optics section about its local axis.
2. The system of claim 1 wherein each imaging optical element has an optical input aperture elongated orthogonal to the axial plane; and,
wherein the plurality of optical funnels in each concentrating optics section each have an optical input aperture underlying the corresponding imaging optical element and elongated orthogonal to the axial plane.
3. The system of claim 2 wherein each imaging optical element has an optical input aperture first axial plane-width in an aperture plane, where the aperture plane is orthogonal to the axial plane, and each imaging optical element focuses light along the tertiary linear focus to a second axial plane-width, smaller than the first axial plane width.
4. The system of claim 2 wherein each imaging optical element is selected from a group consisting of Fresnel lens, cylindrical lens, and acylindrical lens.
5. The system of claim 1 wherein each optical funnel is hollow with inner reflective surfaces, with facets selected from a group consisting of curved and flat.
6. The system of claim 1 wherein each optical funnel has curved exterior surfaces shaped as a compound parabolic concentrator (CPC).
7. The system of claim 1 wherein each optical funnel is a dielectric material with exterior surface facets selected from a group consisting of flat and curved, transmitting R band wavelengths of light accepted at an optical input aperture, initially by refraction, and subsequently to a corresponding receiving surface via total internal reflection (TIR).
8. The system of claim 1 where the PV devices are selected from the group consisting of single-junction and multi-junction cells, each junction having an energy bandgap converting R band wavelengths of light to electrical current.
9. The system of claim 8 wherein the dichroic spectrum splitter reflects light in the R band of wavelengths between 500 and 810 nanometers (nm); and,
wherein the PV devices are selected from a group consisting of double junction tandem cells with energy bandgaps of 1.88 electron volts (eV) and 1.43 eV, and triple junction tandem cells with an energy bandgaps of 2.05 eV, 1.77 eV, and 1.43 eV.
10. The system of claim 8 wherein the dichroic spectrum splitter reflects light in the R band of wavelengths between 650 and 850 nm; and,
wherein the PV devices are single junction cells with an energy bandgap of 1.43 eV.
11. The system of claim 8 wherein the dichroic spectrum splitter reflects light in the R band of wavelengths between 700 and 1000 nm; and,
wherein the PV devices are single junction cells with an energy bandgap of 1.1 eV.
12. The system of claim 1 wherein the reflective trough is rotatable about the primary axis.
13. The system of claim 1 further comprising:
thermal cooling blocks attached to the PV devices.
14. The system of claim 1 wherein dichroic spectrum splitter transmits T band wavelengths of light both greater than near infrared (NIR) and less than NIR, and reflects R band wavelengths in the NIR wavelengths of light.