• Energy Research
• 13. Climate action close

Emerging photovoltaics (PVs), focuses on a variety of applications complementing large scale electricity generation. For instance, organic, dye-sensitized and some perovskite solar cells are considered in building integration, greenhouses, wearable and indoors, thereby motivating research on flexible, transparent, semitransparent, and multi-junction PVs. Nevertheless, it can be very time consuming to find or develop an up-to-date overview over the state-of-the-art performance for these systems and applications. Two important resources for record research cells efficiencies are the National Renewable Energy Laboratory chart and the efficiency tables compiled biannually by Martin Green and colleagues. Both publications provide an effective coverage over the established technologies, bridging research and industry. An alternative approach is proposed here summarizing the best reports in the diverse research subjects for emerging PVs. Best performance parameters are provided as a function of the photovoltaic bandgap energy for each technology and application, and are put into perspective using, e.g., the Shockley-Queisser limit. In all cases, the reported data correspond to published and/or properly described certified results, with enough details provided for prospective data reproduction. Additionally, the stability test energy yield (STEY) is included as an analysis parameter among state-of-the-art emerging PVs.

AbstractGiven the rapid progress in perovskite solar cells in recent years, perovskite/silicon (Si) tandem structure has been proposed to be a potentially cost‐effective improvement on Si solar cells because of its higher efficiency at a minimal additional cost. As part of the evaluation, it is important to conduct a life cycle assessment on such technology in order to guide research efforts towards cell designs with minimum environmental impacts. Here, we carry out a life cycle assessment to assess global warming, human toxicity, freshwater eutrophication and ecotoxicity and abiotic depletion potential impacts and energy payback time associated with three perovskite/Si tandem cell structures using silver (Ag), gold (Au) and aluminium (Al) as top electrodes compared with p–n junction and hetero‐junction with intrinsic inverted layer Si solar cells. It was found that the replacement of the metal electrode with indium tin oxide/metal grid in the tandem cell reduces the environmental impacts significantly compared with the perovskite cell. For all the impacts assessed, we conclude that the perovskite/Si tandem using Al as top electrode has better environmental outcomes, including energy payback time, when compared with the other tandem structures studied. Use of Al in preference to noble metals for contacts, Si p–n junction in preference to intrinsic inverted layer and the avoidance of 2,20,7,70‐tetrakis(N,N‐di‐p‐methoxyphenylamine)9,90‐spirobifluorene (Spiro‐OMeTAD) are environmentally beneficial. The key result found of this work is that the most important factor for the better environmental impacts of these tandem solar cells is the transparency and electrical conductivity of the perovskite layer after it fails. Copyright © 2017 John Wiley & Sons, Ltd.

Abstract Temperature control in solar cells is important as elevated temperature adversely affects performance and lifetime. In building-integrated photovoltaics (BIPV), the overall energy management of an installation must include not only the electrical output from the photovoltaic component but also the net light and heat flows as well as the temperature distributions. As the light reflectance and emittance of solar cells are strongly angle-dependent, total thermal hemispherical emittance should be used instead of normal spectral emittance for accurate calculation of radiative heat transfers and hence solar cell operating temperature. Here we report the analysis of solar cell and internal glass temperature as a function of the measured total hemispherical emittance for the first time. We present a comprehensive model using total hemispherical emittance for determining solar cell and internal glass surface temperatures for insulating and laminated glazing units incorporating an operating photovoltaic cell. In warm weather (30 °C outdoors), solar cell and internal glass temperatures are 45–55 °C in laminated glass while in an insulated glazing the solar cell temperature is 60–75 °C and the internal glass temperature is maintained close to ambient temperature (20 °C indoors). We show that the solar cell front and rear emittance, location, and encapsulation method as well as the type of glazing system impact on the solar cell performance and internal glass temperatures. This study provides recommendations for designing BIPV glazing systems that minimize power loss from the solar cells while optimizing transmitted heat and shows the importance of engineering the correct front and rear solar cell emittances.