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Solar thermal energy has the potential to cover the heat demands of industrial processes. However, there may be a time mismatch between energy supplied by the solar field and the process demand. In this case, a thermal energy storage (TES) allows the use of heat at hours without solar irradiation available. Thermal energy storage for solar hot water or heating systems using low temperatures have been optimized since many decades and are in a mature stage. Developments at high temperatures (above 200 °C) for CSP applications have also been deeply studied. However, until this present paper, limited attention has been paid to TES for solar thermal industrial applications at medium-high temperatures (120-400 °C), where there is a potentially huge demand. When talking about TES several aspects have to be discussed: the heat demand that TES is going to be designed to supply, the material where the energy will be stored and the performance of the TES system which includes not only the material but also tanks, piping and connections. In this review, food, brewery and chemical industries were identified as the industries with higher potential in which TES and solar energy could be integrated. Heat integration methodologies have been reviewed to optimize the use of the solar energy in the industrial processes. Regarding the material, latent heat storage or phase change materials (PCM) were selected for this study because they are a very promising type of storage to be integrated in thermal industrial processes, although the state of the art of latent heat thermal energy storage (LHTES) systems is still far from broad commercialization. Until now, no reviews of latent heat storage for industrial applications at medium-high temperatures (120-400 °C) have been published. Therefore, literature related to PCM and latent heat storage (LHS) systems to be used in industrial thermal processes is here reviewed in order to have a general overview of the available technologies for their integration together with solar thermal energy in industrial processes at both experimental and numerical level. More than 100 potential PCMs for heat storage applications in the range of temperatures 120-400 °C have been found. Inorganic eutectic compositions are the group with more potentially available PCM for these applications, with values of heat of fusion between 74 and 535 kJ/kg. Finally, the works related to the performance of the system from the experimental and modelling point of view were presented. The review of experimental TES systems which include PCM in the studied range of temperatures 120-400 °C showed that most of the experimental set-ups were developed for direct steam generation for CSP applications. Regarding numerical modelling, the type of configuration more simulated is the shell and tube configuration.

Energy use in buildings represents 40% of the total primary energy used in EU and therefore developing effective energy alternatives is imperative. Solar Energy Systems (STS) will have a main role to play as they they contribute directly to heating and cooling of buildings and the provision of domestic hot water. STS are typically mounted on building roofs with no attempt to incorporate them into the building envelope, creating aesthetic challenges and space availability problems. The actions will foster and accellerate long-term development in STS through critical review, experimentation, simulation and demonstration of viable systems for full incorporation and integration into the traditional building envelope. Viable solutions will also consider economic constraints, resulting in cost effective Building Integrated STS. Additionally factors like structural integrity, weather impact protection, fire and noise protection will be considered. The most important benefit of this Action is the increased adoption of RES in buildings. Three generic European regions are considered; Southern Mediterranean; Central Continental and Northern Maritime Europe, to fully explore the Pan-European nature of STS integration. The Action consortium presents a critical mass of European knowledge, expertise, resources, skills and R&D in the area of STS, supporting innovation and conceptual thinking.

Solar electricity generation using concentrating solar thermal collectors faces the challenge of strongly decreased levelized electricity costs by photovoltaic power plants. One of the selling points favouring solar thermal power is the possibility to generate dispatchable power. Concepts discussed here are solar hybridization of conventional or biomass thermal power plants. Another option is the use of thermal energy storage (TES) charged with solar heat which allow to drive the generation of electricity by steam turbines also during hours with no or low solar irradiation. Usually the solar fields of solar thermal power plants utilizing storage with several hours capacity will be much larger than those of plants without storage. This contributes to much higher cost per installed capacity in the case of storage utilization. In this paper the question shall be tackled in a rather fundamental way whether the combination of solar thermal power with cheaper photovoltaic systems plus minimum solar thermal power with storage may give lower levelized electricity cost plus dispatchability than either photovoltaics alone or solar thermal power alone. For the investigation of a combined PV-enhanced solar thermal power plant no specifically developed software was available. Therefore the simulation of the photovoltaic plant and the solar thermal power plant including TES was done individually. For the solar thermal power plant TES storage capacity and solar field area were varied. Solar field area ranged between solar multiple of two and below one. The latter choice would have been senseless without PV-enhancement. Hourly power generations profiles over a complete year were combined and matched in order to generate electricity according to a prescribed demand curve. Using dispatch prescriptions the scheduling of solar thermal power was controlled. With typical generic cost data and variations of those in a sensitivity study the combined levelized electricity cost were determined and analysed. Photovoltaic generation and solar thermal power generation via thermal energy storage may produce high annual capacity factors above 50% due to dispatchable solar power from the thermal storage. Depending on the climatic conditions and on seasonal and daily load profiles the combinations of photovoltaic and solar thermal power may change. Many open questions have to be solved in order to proceed with the basic idea of PV-enhanced solar thermal power generation. Real cost data and optimization requires a specific project case. Then also the selection of the most promising photovoltaic technology and the different solar thermal technologies may be discussed in more detail.

Lineare Fresnelkollektoren sind eine kostengünstige Alternative zu Parabolrinnenkollektoren. Demonstrationsanlagen, die derzeit erprobt werden, bestätigen das Potenzial dieses Gerätetyps, der sowohl für Thermoöl als auch für eine Direktverdampfung ausgelegt werden kann. Vor allem im Sonnengürtel der Erde bieten Sonnenkraftwerke mit Fresnelkollektoren die Möglichkeit, wettbewerbsfähigen Solarstrom zu erzeugen.

Leightweight and flexible organic solar cells are being manufactured economically due to low material costs and efficient production technologies associated with them. The processes such as light absorption and excitation of electrons to a higher energy level and generation of highly mobile charge carriers are achieved by mixing two organic semiconductors. An organic solar cell is composed of a carrier substrate and a photoactive layer embedded between a transparent and a reflective electrode. Organic solar cells can attain the same efficiency as inorganic solar cells by optimizing one semiconductor component. The vacuum coating processes for manufacturing organic solar cells based on small molecules is identified. Continuous reel-to-reel production method for organic solar cells is preferred as high production volumes are achievable due to the attainable high transport speeds and the large web widths.

Since the presentation of Mike Davies' idea of the polyvalent façade [1], the vision of a multifunctional building skin has produced a number of technological developments taking first steps in this direction. Switchable façades with electrochromic or gasochromic glazing have been investigated for many years. Research has mainly concentrated on material and device development [2]. Large-area chromogenic devices are in the discussion for building applications. Recently a large European project has treated the architectural and technical integration of switchable devices into buildings as well as durability and lifecycle aspects [3]. Glazing companies still balk at the risk of a market introduction of glazings which can change its colour dynamically and thus change characteristic properties like total solar energy transmittance and visual transmittance. In this situation it might seem hazardous to try and incorporate even more functions into a glazing unit than the mentioned technologies. In spite of these considerations, it has been the goal of this research to develop a glass façade system that actively controls not only visual light transmission and the solar energy transmission but may even incorporate further processes in the building envelope The extraction and provision of heat within the transparent façade, i.e. at the interface between the artificial interior and natural exterior environments, offers the possibility to completely control the energy flows and comfort conditions at the façade. For this purpose, a four-layer glazing element with two fluid-filled cavities and one gas-filled cavity between the panes was designed (see Figure 1).The outer liquid layer in cavity I reduces the solar irradiation by absorption even in the clear state. Excess solar heat gains are kept outside. During periods of very high solar radiation, the clear fluid in the outer cavity I is replaced by a coloured one thus increasing absorption. In cavity III the liquid layer holds the surface temperature constant at room temperature - in summer it can be cooled down whereas in winter heat can be added to the room. A heat pump could be used for providing the temperature levels needed for these purposes. These large-area, transparent heating and cooling elements show uniform temperatures over their entire surface, which leads to an increased interior comfort range since convection is reduced due to large areas with uniform temperatures. The gas-filled chamber II in the middle, along with the Low-E coating of the third glass pane, further reduces energy transmission in winter (heat losses) and during the summer (solar gains). Shading, heating and cooling therefore become an integral part of the glazed transparent building envelope which is adaptable to the requirements of the different seasons (Figure 2) Of course this vision is not without risk. It has to be transformed from an idea to a reliable technological system before it can be used by designers and engineers to produce completely different buildings.

Commercially available, highly transparent polymer films for transparent insulation applications were investigated systematically as to their relevant optical properties in the solar and infrared wavelength range. The photometric characterisation in the solar range and the calculation of non-spectral, solar optical film properties using models for scattering-absorbing media have shown, that the solar extinction is dominated by scattering occuring mainly at the surface. For various amorphous and semi-crystalline films the root-mean-square surface roughness correlated well with the solar optical thickness. Regarding high infrared absorptance in the wavelength range of about 10 mum the carbon-oxygen single bond is highly effective for commercial materials with maximum service temperatures of about 100 degreesC. For 50 mum thick films of different polymer types with carbon-oxygen single bonds in the molecular structure a good correlation between the concentration of the functional corbon-oxygen group and the non-spectral, infrared optical thickness was found.

Transparent or translucent insulation materials (TIM's) represent a new class of materials with a high potential for increasing the efficiency of solar thermal systems. A large number of materials and material combinations has been subjected to theoretical and experimental investigation. An overview on generic types, characterisation methods, real existing materials available on the market, and the future potential of transparently insulated systems will be given.

Das Grundprinzip der transparenten Wärmedämmung wird neben Grundvarianten erklärt. Die Wirkungsweise und die verschiedenen Typen transparenter Wärmedämmaterialien werden dargestellt. Technische Realisierung als Großmodul oder in kleinformatiger Bauweise ist denkbar. Gestalterische Planung muß ästhetische und phyikalische Aspekte berücksichtigen. Beispiele für realisierte und geplante Projekte werden aufgführt. Eine abschließende Wirtschaftlichkeitsbetrachtung zeigt eine annähernde Gleichwertigkeit zu Opaken Dämmvarianten auf. Zusätzliche Vorteile der transparenten Wärmedämmung werden zum Schluß erläutert, so z.B. Komfortsteigerung.