PV Technologies
Following indication of “Strategic Research Agenda for Photovoltaic Solar Energy Technology” EU PV Technology Platform and indications of CHEETAH experts a range of technologies and topics has been determined and uploaded on CHEETAH Knowledge Exchange Web Area Portal (KEAP), which development is expected to significantly contribute to reaching the overall targets
- Performing joint research addressing well-chosen issues plays an important role in achieving the critical mass and effectiveness required to meet the sector’s ambitions for the definitive technology implementation and industry competitiveness,
CHEETAH Knowledge Exchange portal utilizes them as the base to catalog the offer/demand among consortium partners of requested expertise, infrastructures, equipment, courses, technical documents by promoting further development of knowledge in the same field of interest also outward the consortium.
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Wafer-based crystalline silicon (Si) technology focusses on reducing the specific consumption of silicon and materials in the final PV module by also including new and improved approaches to silicon feedstock and wafer (or wafer-equivalent) manufacturing technologies.
Ultra-thin (in the sub-50 µm thickness range) and kerfless silicon wafers could lead to a substantial cost reduction of silicon modules, to improved solar cell efficiencies, and to novel applications in the field of building-integrated photovoltaics (BIPV). However, such wafers cannot be produced by the traditional method of ingot growth and wire sawing, but require novel production methods that still need to be fine-tuned.
The thin-film silicon solar cell technology is based on a versatile set of materials and alloys, in both amorphous and microcrystalline form, grown from precursor gases by means of a capacitively coupled plasma. The overall objective of the research activities is to increase the device efficiency at competitive costs and with high throughput processes and equipment
Cu(In,Ga)Se2 (CIGS) solar cells are a highly promising alternative to silicon in terms of efficiency record, low temperature coefficient and excellent performance also under low light conditions. Lighter and flexible substrates, have also been recently considered for building or product integrated PV. Developing cost-effective production equipment and processes, improving the TCO / heterojunctions, increasing the understanding of the fundamental physics of these devices and developing micro concentrators system are some examples of nowadays’ research activities.
CdTe polycrystalline thin film solar cells have shown an immense potential in scalability by reaching its maturity for industrial production. Modules have demonstrated long-term stable performance and high efficiency up to 22% under AM1.5 The presence of cadmium in the finished product has been universally accepted as a perception issue more than a real problem since the thin film architecture allows an extremely low amount of cadmium.
III-V Multijunction solar cells are, and have been over the past two decades, the most efficient photovoltaic devices manufactured to date. In multijunction solar cells materials with different bandgaps, namely subcells, are stacked to absorb and convert different fractions of the solar spectrum with maximum efficiency. Todays industry standard is a triple-junction solar cell and four-junction devices appearing in the horizon.
Organic solar cells (OPV) use carbon based materials, typically in forms of small molecules, dendrimers and polymers, to convert solar into electric energy. This enables the low cost production and energy processing which are accompanied by a very high throughput. Additional advantages of OPVs are the light weight and flexibility. Efficiencies up to 11% have already been achieved for OPV devices. The lifetime remains among the main bottlenecks respect inorganic approach but it will be significantly improved before the commercialization
Dye-sensitized solar cells (DSCs) are photovoltaic cells consisting of a dye that absorbs sunlight and a mesoporous TiO2 layer and a liquid electrolyte that transport carriers to opposite electrodes. DSCs are especially suited for building and automobile integrated PV as they can be made into semi transparent coloured glass facades and portable or indoor light harvesting applications since they possess remarkable efficiencies under these conditions.
Hybrid perovskites are a new class of organic/inorganic materials which shown a strong absorption in a broad region of the visible spectrum, a good electron and hole conductivity, and delivering also high open circuit voltages in photovoltaic devices. Providing those characteristics, a plethora of solar cell layouts have been explored and outstanding power conversion efficiency of 21% has been recently certified
Kesterites are tetrahedrally coordinated quaternary semiconductors with general formula I2-II-IV-VI4 (very similar to Cu(In,Ga)Se2 (CIGS) but indium is substituted by the zinc-tin pair and selenium is replaced by sulfur having the aim to give high efficiency thin film solar cells without relying on any critical raw material as Indium or Gallium.
In 1961, Shockley and Queisser stablished a fundamental limit for the efficiency of single gap solar cells. By lifting up some of the premises of their work it is possible to device solar cells for which this limit can be exceeded. In particular, we refer ourselves to the intermediate band, hot carrier and multiple exciton generation solar cells.
Concentration Photovoltaics (CPV) takes advantage of high-efficiency solar cells and uses optical systems to concentrate light over them. If the concentration level is high enough and the optics is affordable enough, the final system becomes cost competitive. CPV technology is nowadays the one achieving maxima cell, module and system efficiencies among all PV technologies.
Worldwide, in the area of PV research PV Module lifetime and reliability is a topic of great interest due to important technical results and long term financial analysis one can make for the cost of solar electricity production as a faction of the PV system price, the annual solar irradiance and the capital interest rate
