| Resumo: |
Nowadays, a particular interest in the development of alternative energy sources arose, especially motivated by the need of reducing the dependency on fossil fuel resources and for providing the reduction of CO2 emissions. An attractive strategy to overcome the present energy problem is using renewable energy sources, such as the direct solar radiation, for producing clean energy. In this sense, the direct conversion of sunlight into electric power by means of photovoltaic systems makes an important contribution to this energy contend in an environmentally friendly way.
In the last decade, solar and photovoltaic (PV) technologies have emerged as a potentially major technology for power generation in the world. Despite the economic crisis, the PV market has continued to grow almost 15 % in 2009 compared to 2008 and the total power installed in the world raised by 45 % and up to 22.9 GW. However, so far, the photovoltaic field has been dominated by devices in which the junction consists of inorganic solid-state materials, usually silicon, profiting from the expertise of the semiconductor industry. In fact, over 85 % of the current production is based on silicon wafer or silicon ribbon technology. A major advantage of this technology is that complete production lines can be bought, installed and being producing within a relatively short time-frame. This predictable production start-up scenario constitutes a low-risk placement with calculable return on investments. Even though these technologies are still very expensive and only survive in very specific groups of the market or with financial supports. Presently, the photovoltaic panels price has been decreased significantly, reaching at the moment 3.5 ¤/W. Nevertheless, these values are still not competitive to the individual consumer and this is, in fact, the major problem limiting the mass production of this type of technologies for domestic purposes - microgeneration. Thus, incentives to incorporate PV technologi  |
Resumo
Nowadays, a particular interest in the development of alternative energy sources arose, especially motivated by the need of reducing the dependency on fossil fuel resources and for providing the reduction of CO2 emissions. An attractive strategy to overcome the present energy problem is using renewable energy sources, such as the direct solar radiation, for producing clean energy. In this sense, the direct conversion of sunlight into electric power by means of photovoltaic systems makes an important contribution to this energy contend in an environmentally friendly way.
In the last decade, solar and photovoltaic (PV) technologies have emerged as a potentially major technology for power generation in the world. Despite the economic crisis, the PV market has continued to grow almost 15 % in 2009 compared to 2008 and the total power installed in the world raised by 45 % and up to 22.9 GW. However, so far, the photovoltaic field has been dominated by devices in which the junction consists of inorganic solid-state materials, usually silicon, profiting from the expertise of the semiconductor industry. In fact, over 85 % of the current production is based on silicon wafer or silicon ribbon technology. A major advantage of this technology is that complete production lines can be bought, installed and being producing within a relatively short time-frame. This predictable production start-up scenario constitutes a low-risk placement with calculable return on investments. Even though these technologies are still very expensive and only survive in very specific groups of the market or with financial supports. Presently, the photovoltaic panels price has been decreased significantly, reaching at the moment 3.5 ¤/W. Nevertheless, these values are still not competitive to the individual consumer and this is, in fact, the major problem limiting the mass production of this type of technologies for domestic purposes - microgeneration. Thus, incentives to incorporate PV technologies into the urban buildings are strongly envisaged.
Solar resource in Europe and worldwide is abundant and is the only offering the perspective of a cost reduction in the future. In particular, Portugal has a privileged geographic location in terms of solar exposition, giving us the opportunity of becoming a European country leader in photovoltaics exploitation. In the past years, several companies began in Portugal the commercialization of photovoltaic systems most of them commercializing silicon technologies. Though the temporary shortage in silicon feedstock, the market entry of companies offering turn-key production lines for thin-film solar cells led to a massive expansion of investments into thin-film capacities between 2005 and 2009. Actually, since 2003 the thin-film PV segment grew in average over 80 % reaching 400 MW, i.e. 10 % of the total PV production in 2007. The high growth rate of thin-film production clearly shows that this technology is gaining more and more acceptance in the PV world market. The diversification of technologies in this field is of extremely importance in order to contribute to a strong photovoltaic sector, able to fulfill different needs with competitive costs. Dye-sensitized solar cells (DSCs), also known as Grätzel solar cells, are an important type of thin-film photovoltaics due to their potential for low-cost fabrication and versatile applications, as flexible or light-weight products. State of the art lab DSCs achieve more than 11 % energy conversion on small area devices. Recent findings indicate that DSC modules could reach the cost targets of 0.6 ¤/W in a near future. Besides their low-cost production, DSCs are able to start producing electricity earlier in the day and finish later, converting not only direct but also diffuse light. Thus, the DSCs when applied to fix panels are able to absorb the non-perpendicular incident solar radiation without needing complex sun tracking systems. This advantageous characteristic when compared to other technologies allows to diversify its application, for instance using DSCs on roofs or in façades. Moreover, DSCs can include elegant architectural elements due to their transparency and different possibilities of color, e.g. in windows.
DSCs are an emergent photovoltaic technology, not commercially available yet and with high potential. Efacec considers that is preferable to assume some risk by investing in a technology under development and achieve at the end a bigger part of the value chain, than investing in a solid and well-known technology and take only small fraction of it. DSCs technology is gaining more and more attention not only by the scientific community but also by several companies all over the world. Nevertheless, in order to reach commercialization of this technology for outdoor applications, more fundamental and technological research is required to answer the key questions related to efficiency, stability, manufacturability and scale-up of production. In Portugal Efacec was pioneer in coordinating a project in consortium with several partners, including FEUP. In this project was developed an innovative sealing process by laser for DSCs, able to overcome the important issue related to the long-term stability of these cells. Additionally, a novel counter-electrode is being developed to replace the typical platinum counter-electrode by a cheaper nanostructured carbon film. Although Efacec has already filled 5 patents with FEUP, the step to be able to commercialize the DSC technology for large-scale power applications, within the PV market for microgeneration, still needs a great investment. Efacec takes advantage of Prof. Grätzel's support that has a privileged relationship with FEUP and is considering the strategic collaboration with international companies with know-how in this field, namely, Pilkingtion, one of the world's largest manufacturers of glass and glazing products, and Solaronix, one of the main suppliers of all of the components involved in the development and the fabrication of dye solar cells, dye solar cell modules and a deliverer of equipment for evaluation and aging of solar cells.
The present project envisages five main achievements:
i) Development of an embedded TCO collector in order to surpass the low conductivity of the typical TCO;
ii) Improvement and optimization for industrial use of the carbon based-counterelectrode;
iii) Optimization of the different operating steps for individual cells and modules preparation;
iv) Scale-up of the present technology for ETCO-based individual cells up to 30 x 30 cm2 and for ETCO-based DSC modules to dimensions up to 60 x 60 cm2;
v) Fundamental research to continue the improvement of the technology. |