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A simple model to evaluate the irradiance incident on tilted surfaces of various orientations is proposed in this paper. It is based on the knowledge of the monthly daily average values of global and diffuse radiation on horizontal surfaces and their distributions over a period of a day. These distributions are approximated by a modified Gaussian expression with two parameters, which take into account the morning-to-afternoon asymmetries. Integrating the irradiance over a period of an hour or a day, values of monthly hourly average and daily on variously oriented surfaces have been calculated for the locations of Barcelona, Genoa, and Montreal. The calculated values are generally in good agreement with the data derived by the observations.

Abstract The ground-level spectral distribution of direct solar irradiance at Reunion Island was measured for six bands covering the spectrum of solar radiation. The measurements, distributed over one year, were made under clear sky conditions with a pyrheliometer (Eppley, NIP) and six large pass-band flat filters. Good stability of spectral irradiances as a function of Solar height allows us to propose approximate relationships which significantly characterize the irradiance into each spectral band. Measurements at Reunion vary significantly from data obtained with the same apparatus in a northern hemisphere continental area (Lyon). The determination of aerosol attenuation coefficients, for different spectral bands, allows the establishment of a mean curve, for these coefficients as a function of wavelength, characteristic of marine aerosols.

Abstract Periodically adjusted parabolic mirror/evacuated tube absorber combinations are evaluated using computer simulation methods. The results show that a 4–6 X reflector adjusted 10–15 times per year, operating at 150°C, competes favourably in cost-effective terms with a fixed reflector CPC collector operating at 50°C. Periodically adjusted collectors are advocated for medium temperature industrial applications below 200°C.

Presentation d'une technique simple de calcul du spectre et de l'energie du rayonnement solaire horaire sur la surface d'un bassin solaire a partir du seul indice moyen mensuel de clarte. Utilisation de cette methode pour la simulation d'un modele de bassin solaire de laboratoire et comparaison avec les resultats obtenus pour ce meme modele en utilisant les donnees du rayonnement solaire a Perpignan pendant la periode 1977-79

Abstract Maximally concentrating collectors include the class of ideal concentrating collectors, but are a more general class offering many more practical possibilities. By evaluating such configurations using the concept of maximal flux concentration, based upon average radiation flux concentration over the acceptance angle, clear ray trace comparisons may be made between different collector configurations. These comparisons allow the most effective configuration to be selected for a given application. An example of a comparatively simple and practical two-stage concentrator having equal or better maximal performance than previous work for high rim angle primaries is given. This uses an unusual straight section of reflector and allows rays to cross from one reflector segment of the secondary to another. Versions which allow concentration up to 90% of maximal are described, as are versions achieving 80% with high collection efficiency. Use of the 1 sin θ max geometrical concentration criterion based upon aperture ratios is suggested to be inappropriate for comparisons.

Abstract One of the greatest challenges in a photovoltaic solar power generation is to keep the designed photovoltaic systems working with the desired operating efficiency. Towards this goal, fault detection in photovoltaic plants is essential to guarantee their reliability, safety, and to maximize operating profitability and avoid expensive maintenance. In this context, a model-based anomaly detection approach is proposed for monitoring the DC side of photovoltaic systems and temporary shading. First, a model based on the one-diode model is constructed to mimic the characteristics of the monitored photovoltaic array. Then, a one-class Support Vector Machine (1SVM) procedure is applied to residuals from the simulation model for fault detection. The choice of 1SVM approach to quantify the dissimilarity between normal and abnormal features is motivated by its good capability to handle nonlinear features and do not make assumptions on the underlying data distribution. Experimental results over real data from a 9.54 kWp grid-connected plant in Algiers, show the superior detection efficiency of the proposed approach compared with other binary clustering schemes (i.e., K-means, Birch, mean-shift, expectation–maximization, and agglomerative clustering).

Today, investigations on degradation and failure mechanisms in solar cells are often based on accelerated ageing tests (AAT), where failure effects are reproduced and quantified within a much shorter time period than the actual lifetime. This paper presents a study upon a novel approach of AAT for high concentration photovoltaic (HCPV) cells. The intended approach aims to overcome several limitations encountered in most of the AAT adopted up today, proposing the use of an alternative experimental set-up for performing nearly 400 times faster and more realistic thermal cycles, under real sun conditions (irradiation cycling), without the involvement of any environmental chamber. The cumulative impact of such very rapid irradiation/thermal cycles on the ageing of HCPV assemblies can be determined, both quantitatively and qualitatively, by evaluating specific pre-ageing and post-ageing diagnostic measurements by means of I–V characterization and scanning acoustic microscopy (SAM). The proposed irradiation/thermal cycling arrangement was successfully employed for performing accelerated ageing of both HCPV assemblies (cell receiver and heat sink) and bare HCPV cell receivers. Ultimate goal of this AAT approach is to provide the basis for a future work on the reliability analysis of the main degradation mechanisms and failure propagation in HCPV cell assemblies. 2015 Elsevier Ltd. All rights reserved.

Values of the Angstrom turbidity coefficient, β, at 0.50 μm wavelength have been determined in Lagos, a tropical coastal city in Nigeria, for 17 months between 1990 and 1991 using a Volz sun photometer. The results obtained indicate high variability of aerosol loading, though the city, on average, experiences high turbidity for most parts of the year. An annual average of 0.299 with a standard deviation of 0.187 was found. On average, the month of January experienced the highest turbidity, with a mean value of 0.497, while November experienced the lowest aerosol loading on average with a value of 0.225. The aerosols influencing the city are both of maritime and Saharan origin, coupled with locally produced particulates from industries and automobile combustion. Possible effects of the Mount Pinatubo haze may be the cause of the increase of turbidity values in the second half of 1991 when compared with values for the same period in 1990. Addition of β in the Liu and Jordan type diffuse fraction correlation indicates little improvement in standard error.