Arturo Morales AcevedoCINVESTAV del IPN
Electrical Engineering Department
PV Research & Innovation perspectives
LIFyCS
1er. Taller de Innovación
Fotovoltaica y de Celdas Solares
Solar Irradiation in MexicoAnnual daily average
Units are in kW-h/m2
4
Electrical Energy for
rural regions
Grid-connected Photovoltaic SystemsNet Metering
220 houses with a 1 kW PV system in Mexicali, B. C.
How does a solar cell work?
Energy Losses in a conventional
Solar Cell
Diverse Technologies
Solar Cells
Silicon
III-V
II-VI
Polycristalline
Si Monocristalline ········Large scale production
Si Multicristalline ········ Large scale production
Si microcristalline ········ Small production
Si amorphous ········ Small production
GaAs ·······Space applications
InP ·······Space applications
CdTe ·······Medium production
CuInGaSe2
CuInSe2, CuInS2········Small production
other Dye Sensitized/Organic ········I&D
Si spherical ········I&D or Pilot production
Si ribbon ········ Small production
Present situation
1st solar cell generation
Present technology for
silicon solar cells
Typical conversion efficiencies 13-17%, but
the highest laboratory efficiency is 24-25%
PV radio-telephone system
installed in rural Puebla
First PV system using
silicon solar cells and
modules made in
CINVESTAV-Mexico
in 1977.
2nd solar cell generation
CuInGaSe2 thin film solar cells
Solar cells
made by Honda
in Japan, with
efficiencies of 11 -
12%. The highest
reported efficiency
is 20% (small
area).
Subestrate structure
CdS/CdTe thin film solar cells
Wu, X., Keane, J.C., Dhere, R.G., DeHart, C., Albin, D.S., Duda, A., Gessert,
T.A., Asher, S., Levi, D.H., Sheldon, P., 2001a. 16.5%-efficient CdS/CdTe
polycrystalline thin-film solar cells. In: Proceedings of 17th European PVSEC,
pp. 995–1000.
Maximum
efficiency = 16.5%
Thin film amorphous silicon solar cell
Carrier transport is different
than for conventional silicon
solar cells. Carrier
recombination is larger, and
then the efficiency is very
much less.
Maximum
efficiencies
around 12.7%
Solar radiation
Hybrid HIT solar cells
Amorphous silicon
Crystalline Silicon
Efficiencies near
23% in Industrial
scale (Sanyo)
Low temperature
processing
Amorphous silicon
Schematics of a “plastic” solar cellPET - Polyethylene terephthalate, ITO - Indium Tin Oxide, PEDOT:PSS –
[Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)], Active Layer
(usually a polymer:fullerene blend), Al - Aluminum.
Solar cells based on polymers
Dye sensitized solar cellsPhoto-electrochemical Cells
• Nano-porous metallic oxide with a large
exposed surface.
• luminous absorption by the dye molecules.
• Electron and hole transport in the solid and
ion transport in the solution.
Dye ZnO nanorod based solar cells
3rd solar cell generation
New concepts for 3rd generation
solar cells
More energy obtained from solar radiation with:
I. More participating bands:
• Tandem, intermediate bands and spectral
separation.
II. More work from each absorbed photon:
• Impact ionization and “hot carriers”.
III. Apropriate photon redistribution:
• Photon “up” and “down” conversion.
Multi-junction tandem solar cells
Tandem + solar radiation concentration
Concentrating (CPV)
systems will use very
expensive, but highly
efficient solar cells in
order to have PV
energy cost reduction.
It can be shown that
efficiency of a solar
cell ideally increases
when the radiation
intensity increases.
Quantization Effects
Size Quantum Effects
• Dramatic variation of optical and electronic properties.
• Large blue shift of the absorption edge.
• Conservation of momentum relaxed. Crystal momentum is not a good quantum number.
• Greatly enhanced exciton absorption at 300 K.
• Slowed relaxation and cooling (~10X) of photogenerated hot electrons and holes.
• Coulomb coupling and Auger processes greatly enhanced (including exciton multi-plication).
• Conversion of indirect semiconductors to direct semiconductors.
• Discrete energy levels / structured absorption and photoluminescence spectra.
• Greatly enhanced oscillator strength per unit volume (absorption coefficient).
• Greatly enhanced non-linear optical properties.
• Greatly modified pressure dependence of phase changes and direct to indirect transitions.
• Efficient anti-Stokes luminescence.
Enhanced Multiple Exciton
Generation
Silicon Nanocrystals
MEG in Silicon Nanocrystals
Photonic conversion
Silicon Rich Oxide
Zhenrui Yu, Mariano Aceves-Mijares andMarco Antonio Ipiña Cabrera
Nanotechnology 17 (2006) 3962–3967
Polymorphous Silicon
A. Remolina, B. M. Monroy, M. F. García-Sánchez, A. Ponce,M. Bizarro, J. C. Alonso, A. Ortiz and G. Santana
Nanotechnology 20 (2009) 245604
Nanoparticle Plasmonic
Solar Cells
A group at ANU measured an enhanced photocurrent attributed to the increased trapping of light scattered into a thin-film silicon cell by silver metal nano-particles excited at their surface plasmon resonance.
Perspectives for the contribution of solar energy to the
world energy supply for this century
Conclusion
Further research and development is needed in
order to achieve new kinds of solar cells which
are competitive with other electrical energy
sources. High efficiencies and low costs are both
required.
PV solar energy will become a significant part of
the total world energy by 2050, based on
innovation. Then, at the end of this century, solar
PV electricity will become the most important
energy source in the world.
Costo de algunos materiales
para celdas solares
Wadia, C., Alivisatos, A., Kammen, D. M., 2009. Environ. Sci. Technol 43, 6.