Programm Photovoltaik Ausgabe 2009 ... - Bundesamt für Energie BFE

3/10
The “intermediate band” approach pursues a better use of
the solar spectrum by using intermediate band materials
(Fig. 3). These materials are characterised by the existence
of an electronic energy band within what otherwise
would be a conventional semiconductor bandgap. According
to the principles of operation of this cell, the intermediate
band allows the absorption of low bandgap energy
photons and the subsequent production of enhanced
photocurrent without voltage degradation. The Project expects
also to identify as much intermediate band material
candidates as possible as well as to demonstrate experimentally
the principles of operation of the intermediate
band solar cell by using quantum dot solar cells as workbenches.
Diffuse light
Spectrally adapted solar cell(s)
Photonic layers.
Mirror for extremely
small band. Transmit
all the r est.
Fig. 4. Luminescent concentrator with
photonic crystal.
Mirror
Within the activity involving manufacturing, it is expected
to clear the way towards commercialization for those
most promising concepts. This is the case of the multijunction
solar cells and within this activity it is expected
to develop, for example, trackers with the necessary
accuracy to follow the sun at 1000 suns, “pick and
place” assembling techniques as to produce concentrator
modules at competitive prices as well as to draft the
normative that has to serve as the framework for the
implementation of these systems.
Fig. 3. The principle of the IBC.
As mentioned, under the “molecular based concepts”
heading, it is expected to find dyes and
molecules capable of undergoing two-photon processes.
Dyes -or quantum dots- suitable to be
incorporated into flat concentrators are also pursued.
Flat concentrators are essentially polymers
plates, that by incorporating these special dyes to
their structure, are capable of absorbing high energy
photons and re-emit them as low energy
photons that ideally match the gap of the solar
cells. This emitted light is trapped within the concentrator
usually by internal reflection and, if the
losses within the concentrator are small, can only
escape by being absorbed by the cells.
Fig. 5. An example of novel concentrator
lenses.
Project Structure: The Project is coordinated by Prof. Antonio Luque (Instituto de Energía Solar) assisted
by Projektgesellschaft Solare Energiesysteme GmbH (PSE). The Consortium involves 19 research
institutions listed at the side of this text. As mentioned, to make the better use of the solar spectrum
declared above, the project is structured along five research development and innovation activities:
1) Multijuntion solar cells. The activity is leaded by FhG-ISE with the participation of RWE-SSP, IES-
UPM, IOFFE, CEA-DTEN and PUM.
2) Thermophotovoltaic converters. Is headed by IOFFE and CEA-DTEN. IES-UPM and PSI participate
also in its development.
3) Intermediate band solar cells. The activity is leaded by IES-UPM. The other partners directly involved
are UG, ICP-CSIC and UCY.
4) Molecular based concepts. The activity is leaded by ECN. The other groups involved are FhG-
IAP, ICSTM, UM and Solaronix.
5) Manufacturing techniques and pre-normative research. The activity is leaded by ISOFOTON.
IES-UPM and JRC are involved also in the activities.
FULLSPECTRUM, T. Meyer, Solaronix
155/290