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Abstract Seasonal solar thermal energy storage (SSTES) has been investigated widely to solve the mismatch between majority solar thermal energy in summer and majority heating demand in winter. To study the feasibility of SSTES in domestic dwellings in the UK, eight representative cities including Edinburgh, Newcastle, Belfast, Manchester, Birmingham, Cardiff, London and Plymouth have been selected in the present paper to study and compare the useful solar heat available on dwelling roofs and the heating demand of the dwellings. The heating demands of space and hot water in domestic dwellings with a range of overall heat loss coefficients (50 W/K, 150 W/K and 250 W/K) in different cities were calculated; then the useful heat obtained by the heat transfer fluid (HTF) flowing through tilted flat-plate solar collectors installed on the dwelling roof was calculated with varied HTF inlet temperature (30 °C, 40 °C and 50 °C). By comparing the available useful heat and heating demands, the critical solar collector area and storage capacity to meet 100% solar fraction have been obtained and discussed; the corresponding critical storage volume sizes using different storage technologies, including sensible heat water storage, latent heat storage and various thermochemical sorption cycles using different storage materials were estimated.

The solar hybrid-wall is widely used in natural ventilation and air heating in buildings. This article aims to experimentally study the induced chimney effect in a solar hybrid double wall. The effect of the air ventilation gap width and solar radiation intensity on the temperature distribution and induced air flow rate at the outlet of the hybrid wall was investigated with a variable chimney gap width-to-height ratio between 1:10 and 3:5. The results demonstrated that a lowest temperature position exists in the air gap and the position varies with the width of the air gap. The average air velocity in the air gap increases with the strength of the radiation intensity, and it shows a peak value with decreasing chimney gap width. The induced mass flow rate increases with both the radiation intensity and the chimney gap width. The optimum chimney gap width-to-height ratio is around 0.2–0.3 according to the coupling effect of the temperature and the air volume. Smoke visualization experiment demonstrates that reverse flow occurs in solar chimneys with a gap width-to-height ratio bigger than 0.3. It was found that the prediction method available in the literature can be well applied to narrow chimneys with a gap width-to-height ratio less than 0.3.

Abstract Crystallinity, optical band gap, resistivity and photoresponse of thermally evaporated In2S3 thin films deposited at a temperature of 350 °C and further annealed in sulfur vapour at different temperature range of 200–300 °C is investigated. It is observed that with an increase of annealing temperature, predominantly β-In2S3 phase is formed and the optical band gap for indirect allowed transitions increases from 1.6 eV to 2.0 eV and for direct allowed transitions from 2.3 eV to 2.7 eV. The electrophysical properties indicate that the activation mechanism of conductivity with an activation energy in the range of 0.5–0.73 eV, which is typical for the presence of indium vacancies in the β-In2S3 crystal structure and for the replacement of sulfur by oxygen atoms. It is also noted that sulfur annealing at temperatures of 250–300 °C leads to an increase in the conductivity and photosensitivity of films, which is suitable for photovoltaic applications.

Abstract In this work, the scalable screen printing process has been adopted to prepare low-cost and earth-abundant tin selenide (SnSe) films to study as the counter electrode in dye-sensitized solar cells (DSSCs). The SnSe powder was synthesized by solid state reaction method and corresponding films were fabricated by screen printing technique. The electrocatalytic activity of SnSe for redox iodide/triiodide (I−/I3−) couple and charge transfer resistance at the CE/electrolyte interface were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The DSSC with SnSe counter electrode exhibited with power conversion efficiency (PCE) of ~5.76% with open-circuit voltage of 0.63 V and short circuit current density of 12.39 mA/cm2 whereas the DSSC with platinum counter electrode showed PCE of 8.09% with open-circuit voltage of 0.68 V and short circuit current density of 14.77 mA/cm2. Thus, earth abundant and low cost SnSe films fabricated by screen printing technique could be an alternative to costly platinum counter electrode in DSSC.

The effect of soiling in flat PV modules has been already studied, causing a reduction of the electrical output of 4% on average. For CPV's, as far as soiling produces light scattering at the optical collector surface, the scattered rays should be definitively lost because they cannot be focused onto the receivers again. While the theoretical study becomes difficult because soiling is variable at different sites, it becomes easier to begin the monitoring of the real field performance of concentrators and then raise the following question: how much does the soiling affect to PV concentrators in comparison with flat panels?? The answers allow to predict the PV concentrator electrical performance and to establish a pattern of cleaning frequency. Some experiments have been conducted at the IES-UPM and CSES-ANU sites, consisting in linear reflective concentration systems, a point focus refractive concentrator and a flat module. All the systems have been measured when soiled and then after cleaning, achieving different increases of ISC. In general, results show that CPV systems are more sensitive to soiling than flat panels, accumulating losses in ISC of about 14% on average in three different tests conducted at IESUPM and CSES-ANU test sites in Madrid (Spain) and Canberra (Australia). Some concentrators can reach losses up to 26% when the system is soiled for 4 months of exposure.

Abstract Recent progress in the electronic quality of high-performance (HP) multicrystalline silicon material is reported with measurements and modeling performed at various institutions and research groups. It is shown that recent progress has been made in the fabrication at Trina Solar mainly by improving the high excess carrier lifetimes τ due to a considerable reduction of mid-gap states. However, the high lifetimes in the wafers are still reduced by interstitial iron by a factor of about 10 at maximum power point (mpp) conditions compared to mono-crystalline Cz wafers of equivalent resistivity. The low lifetime areas of the wafers seem to be limited by precipitates, most likely Cu. Through simulations, it appears that dislocations reduce cell efficiency by about 0.25% absolute. The best predictors for PERC cell efficiency from ingot metrology are a combination of mean lifetime and dislocation density because dislocations cannot be improved considerably by gettering during cell processing, while lifetime-limiting impurities are gettered well. In future, the material may limit cell efficiency above about 22.5% if the concentrations of Fe and Cu remain above 1010 and 1013 cm−3, respectively, and if dislocations are not reduced further.