Luminescent solar concentrator
A solar concentrator device comprising a solar concentrator element comprising a radiation transmissive surface, a radiation absorptive material and a radiation concentrating/collection point and disposed on the incident radiation side thereof a recapture element for recapturing at least a portion of radiation lost from the concentrator element has improved solar radiation collection efficiency by reintroducing recaptured radiation into the concentrator element or by propagating said recaptured radiation through the recapture element to a radiation concentration point associated with the recapture element. It has been found that planar elements having a grooved or corrugated outer surface make for very good recapture elements for planar concentrator elements.
1. A radiation concentrator device for concentrating incident radiation comprising at least one concentrator element and at least one recapture element, wherein the at least one concentrator element comprises at least one transmissive surface for receiving radiation into the element and at least one concentration point for positioning a radiation receiving device to which point radiation may be directed by multiple reflections; and wherein the at least one recapture element, which is disposed in optical arrangement with the at least one transmissive surface of the concentrator element, comprises at least one concentration point for receiving recaptured radiation and is configured to
a. transmit incident radiation to the concentrating element,
b. re-capture by optical means escaped radiation from the concentrator element; and
c. redirect at least a portion of the escaped radiation to the at least one concentration point.
2. A radiation concentrator device as claimed in claim 1 , wherein the concentrator element comprises a radiation-absorptive material capable of absorbing incident radiation and re-emitting radiation.
3. A radiation concentrator device as claimed in claim 1 , wherein the concentrator element is a luminescent concentrator element having a first transmissive surface for receiving incident radiation into the element and at least one surface for a radiation receiving device and which luminescent concentrator element has disposed thereon and/or therein one or more luminescent material capable of absorbing radiation and re-emitting radiation.
4. A radiation concentrator device as claimed in claim 1 , wherein the recapture element comprises an inner surface disposed adjacent to and in optical arrangement with the transmissive surface of the concentrating element and an outer surface for receiving incident radiation into the radiation concentrator device and by which escaped radiation from the concentrator element may be retained within the radiation concentrator device by reflection from said outer surface.
5. A radiation concentrator device as claimed in claim 4 , wherein the outer surface of the recapture element comprises a plurality of ridges and grooves.
6. A radiation concentrator device as claimed in claim 5 , wherein the plurality of ridges and grooves are substantially parallel.
7. A radiation concentrator device as claimed in claim 5 , wherein the plurality of ridges and grooves form a corrugated surface of suitably aligned planar surfaces.
8. A radiation concentrator device as claimed in claim 7 , wherein the corrugated planar surfaces are arranged relative to one another at ridge and groove angles of from 75° to 105°.
9. A radiation concentrator device as claimed in claim 8 , wherein the ridge and groove angles are substantially right angles.
10. A radiation concentrator device as claimed in claim 1 , wherein the transmissive surface of the concentrator element is a planar surface.
11. A radiation concentrator device as claimed in claim 1 , which comprises:
a luminescent concentrator element in sheet form having a first planar transmissive surface for receiving radiation and a second planar surface substantially co-planar with said first planar transmissive surface, at least one edge to which radiation may be directed by internal reflection for receipt by a radiation receiving device, and disposed thereon and/or therein one or more luminescent material capable of absorbing radiation and re-emitting radiation; and
a recapture element comprising a planar inner surface disposed in co-planar optical arrangement with the planar surface of the concentrator element and an outer surface for receiving incident radiation into the concentrator, which outer surface comprises a plurality of ridges and grooves by which escaped radiation from the concentrating element may be retained within the concentrator by means of reflection against the outer surface.
12. A radiation concentrator device as claimed in claim 11 , wherein the plurality of ridges and grooves are substantially parallel and formed by a series of aligned corrugated planar surfaces.
13. A radiation concentrator device as claimed in claim 11 , wherein the concentrator element is a quadrangular sheet having four edges at least one of which is configured for optical arrangement with a radiation receiving device.
14. A radiation concentrator device as claimed in claim 11 , wherein the second planar surface of the concentrator element is provided with a reflecting means for reflecting incident and re-emitted radiation striking the second planar surface from within the concentrator element back into the concentrator element.
15. A photovoltaic device comprising a radiation concentrator device as defined in claim 1 and one or more photovoltaic cells or array of photovoltaic cells.