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• Thermal comfort using building integrated photovoltaic-vacuum system was calculated. • The indoor room temperature for BIPV-vacuum glazing was calculated from one-dimensional heat-model. • Vacuum-PV-single glazing structure was found to be suitable for UK climate. Building integrated photovoltaic (BIPV)-vacuum system is promising for advanced window application due to its ability to reduce heat transfer, control over admitted solar heat and generates environmentally benign electricity. In this work, numerically thermal comfort for an unfurnished room comprising of BIPV-vacuum glazing was evaluated for the United Kingdom (UK) climate. Required parameters to determine thermal comfort, one-dimensional heat transfer model was developed and validated for BIPV-vacuum glazing and results were compared with BIPV-double-pane glazing system. PV cell temperature difference between these two different types of glazing was 24 °C. For the UK climate, BIPV-vacuum glazing offered 26% higher room temperature at clear sunny day compared to BIPV-double system. BIPV–vacuum glazing system provided soothing or comfortable thermal comfort during mid-day period for a clear sunny day at temperate climate. In a combined BIPV-vacuum glazing, it was also predicted that vacuum glass facing external ambient is suitable for the UK climate whilst vacuum glass facing internal room ambient is applicable for Indian climate. [ABSTRACT FROM AUTHOR]

A compact high concentrating photovoltaic module based on cassegrain optics is presented; consisting of a primary parabolic reflector, secondary inverse parabolic reflector and a third stage homogeniser. The effect of parabolic curvatures, reflector separation distance and the homogeniser’s height and width on the acceptance angle has been investigated for optimisation. Simulated optical efficiencies of 84.82–81.89% over a range of ±1° tracking error and 55.49% at a tracking error of ±1.5° were obtained. The final singular module measures 169 mm in height and 230 mm in width (not including structural components such as cover glass). The primary reflector dish has a focal length of 200 mm and is a focal with the secondary inverse reflector which has a focal length of 70 mm. The transparent homogenising optic has a height of 70 mm, an entry aperture of 30 × 30 mm and an output aperture of 10 × 10 mm to match the solar cell. This study includes an analysis of the optical efficiency, acceptance angle, irradiance distribution and component errors for this type of concentrator. In particular material stability and the surface error of the homogeniser proved to be detrimental in theoretical and experimental testing – reducing the optical efficiency to ∼40%. This study proves the importance of material choice and simulating optical surface quality, not simply assuming ideal conditions. In the experimental testing, the acceptance angle followed simulation results as did the optical efficiency of the primary and secondary reflectors. The optical efficiency of the system against increasing solar misalignment angles is given for the theoretical and experimental work carried out. [ABSTRACT FROM AUTHOR]

A prototype concentrating photovoltaic (CPV) module was designed and constructed with a low concentrating dielectric compound parabolic concentrator (DiACPC) for outdoor characterisation. The designed concentrator has acceptance half angles of 0° & 55° with a concentration ratio of 2.8. This concentrator design is suitable for building facade integration in higher latitude (>55°) locations. A small prototype CPV module of 300 mm × 300 mm was constructed with 2 strings of 14 solar cells in series. The prototype CPV module was characterised in Edinburgh for different weather conditions and the performance is compared with a similar non-concentrating counterpart (i.e. a flat-plate module with the same PV cell area and technology) in real time. The electrical output results for a cloudy day, rainy day and a day with sunny intervals have been reported to evaluate the performance of the concentrating system with direct and diffuse irradiance. The maximum power output of the CPV module on the day with sunny intervals was found to be 5.88 W for a solar radiation input of 943 W/m 2 , which is 2.27 times higher than that for the flat-plate module. The average short circuit current of the CPV module was found to be 2.22 times higher than that of the flat-plate module. The average open circuit voltage and fill factor of the CPV module were also found to be 2.5% and 1.6% higher than that for the flat-plate module. The CPV module is found to be very effective on the rainy day with an average power output of 0.13 W, which is 2.17 times higher than the average output power for the flat-plate module. [ABSTRACT FROM AUTHOR]

A novel densely packed receiver for concentrating photovoltaics has been designed to fit a 125× primary and a 4× secondary reflective optics. It can allocate 16 1cm 2 -sized high concentrating solar cells and is expected to work at about 300 Wp, with a short-circuit current of 6.6 A and an open circuit voltage of 50.72 V. In the light of a preliminary thermal simulation, an aluminum-based insulated metal substrate has been use as baseplate. The original outline of the conductive copper layer has been developed to minimize the Joule losses, by reducing the number of interconnections between the cells in series. Slightly oversized Schottky diodes have been applied for bypassing purposes and the whole design fits the IPC-2221 requirements. A full- scale thermal simulation has been implemented to prove the reliability of an insulated metal substrate in CPV application, even if compared to the widely-used direct bonded copper board. The Joule heating phenomenon has been analytically calculated first, to understand the effect on the electrical power output, and then simulate, to predict the consequences on the thermal management of the board. The outcomes of the present research will be used to optimize the design of a novel actively cooled 144-cell receiver for high concentrating photovoltaic applications. [ABSTRACT FROM AUTHOR]

In the present study, we model and analyse the performance of a dielectric based linear concentrating photovoltaic system using ray tracing and finite element methods. The results obtained are compared with the experiments. The system under study is a linear asymmetric CPC (Compound Parabolic Concentrator) designed to operate under extreme incident angles of 0° and 55° and have a geometrical concentration ratio of 2.8×. Initial experiments showed a maximum PR (power ratio) of 2.2 compared to a non concentrating counterpart. An improvement to this has been proposed and verified by adding a reflective film along the edges of the concentrator to capture the escaping rays and minimise optical losses. The addition of the reflective film changes the incoming distribution on the solar cell. Results show an increase of 16% in the average power output while using this reflective film. On including the thermal effects it was found that the overall benefit changes to about 6% while using a reflective film. Additionally, the effects of the non-uniformity of the incoming radiation are also analysed and reported for both the cases. It is found that adding the reflective film drops the maximum power at the output by only 0.5% due to the effect of non-uniformity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Prototype CPV modules for building integration are designed and characterised. [•] Modified CPV module for minimum optical losses shows superior performance. [•] A maximum power ratio of 2.27 compared to similar flat plate module is achieved. [•] The maximum experimental optical efficiency of 80.5% is achieved. [•] Detail Optical loss of the dielectric concentrator has been investigated. [Copyright &y& Elsevier]

Abstract: Concentrating photovoltaic technology is one of the fastest growing solar energy technologies achieving electrical conversion efficiency in excess of 43%. The operating temperature of a solar cell strongly influences the performance of a photovoltaic system reducing its efficiency with a negative temperature coefficient. Thus, cooling systems represent a very important aspect in concentrating photovoltaic applications. This work presents an overview of micro- and nano-technologies applicable to passive CPV cooling and associated manufacturing technologies (such as monolithic applications). Among the different technologies, carbon nano-tubes and high-conductive coating are the most promising technologies to offer the best CPV cooling performance. A critical assessment of the technological review has also been made. [Copyright &y& Elsevier]

Solar cell characterization is carried out by current-voltage (I-V) and spectral response measurements. These characteristics of the solar cell depend on solar cell design, fabrication, material properties, junction depth and optical coatings. Generally, during module manufacturing, solar cells of similar wattage are used and spectral response (SR) including external quantum efficiency (EQE) and internal quantum efficiency (IQE) characteristics are not given any attention. It is observed that similar wattage rating crystalline solar cells have slight variation in their spectral response behavior over the wavelength range (300–1100 nm). In this paper, the effect of shading on the crystalline solar cells of the module having same power output and slight difference in spectral response are experimentally investigated. The maximum and minimum drop in short circuit current of the module is observed to be 84.2% and 34.6% when the solar cells of high and low spectral response are shaded. Minority carrier diffusion length and dead layer thickness parameters of solar cells are also calculated from the short and long wavelength region of the spectral response curve. It is found that the effect on module output is high in case of shading a cell having maximum diffusion length and minimum dead layer length. It is concluded that spectral response of a solar cell is an additional parameter that must be considered apart from cell I-V characteristics in module fabrication for superior and uniform performance in the field. [ABSTRACT FROM AUTHOR]

Abstract: Japan started implementing a national Feed-In Tariff (FiT) mechanism on the 1st July 2012, which included specific payment tariffs for solar photovoltaic (PV) installations. This marks a new era in the renewable energy landscape in Japan. This paper aims at analysing the solar PV prospect in Japan, particularly in both residential and non-residential sectors. The paper presents, first, an overview of energy trends in Japan prior to the Fukushima event. This is followed by a short review of solar PV progress in the country, highlighting the major policies and programmes that have been implemented as well as the installations that have been carried out over the past two decades. Next, the financial impact of the new FiT scheme on consumers is evaluated. The financial analysis investigates the total profit, the average annual return on investment and the payback period. For a comparison purposes, a similar financial analysis is also conducted with selected countries around the world – namely Germany, Italy and the United Kingdom. The results from this analysis indicate that the new Japanese FiT rate generates a good profit, a moderate annual return on investment and an acceptable payback period, suggesting an increasing trend of solar PV uptake over the next years. [Copyright &y& Elsevier]

Highlights: [•] A novel type of solar concentrator is presented. [•] The geometrical properties and the optical concentration gain are analysed. [•] It provides significant gain within its acceptance angle, as high as 13.54×. [•] The MSDTIRC is a better alternative design for the BIPV systems. [ABSTRACT FROM AUTHOR]