Elevated prices and lack of proper legislation and government incentives have been the main barriers in the development of the photovoltaic market in Brazil. In an attempt to overcome those barriers, a microgrid model was proposed and simulated. In the proposed microgrids, residential consumers are connected to each other to maximize the investment return by trading the surplus of generated energy among them. Different topologies and scenarios were studied from electrical energy and economic standpoints. Stochastic data of solar radiation were simulated for the city of Viçosa, Minas Gerais, Brazil, for the period of one year, considering the statistical behavior of a series over 20 years. The system output power and energy balance were calculated considering a model for photovoltaic generators and the radiation simulated data. By determining the generated energy and electrical needs of the microgrid members, the cash flow and economic feasibility were calculated. Sensitivity analyses were performed by varying economic parameters to determine situations where investment becomes feasible. This paper shows that microgrid contributes to improve the economics and the initial investments. The number of participants in a microgrid, the electricity and the equipment costs are important parameters to speed up the economic and technical feasibility process.

The choice of a particular PV technology for best performance is sometimes based upon a single factor or single operating condition. However, many parameters have functionalities that oppose each under actual operating conditions. In this paper, the comparisons of different PV module technologies under moderate environmental conditions (Tropical Climate Zone, Belo Horizonte, Brazil) are explored based upon the two competing parameters of soiling-layer spectral effects and panel operating temperature. Specifically, low-bandgap PV technologies (e.g., Si or Cu(In,Ga)(SSe)₂) are reported to have performances less affected by the absorption of incoming sunlight than higher-bandgap absorbers (e.g., a-Si:H or CdTe). However, the opposite is true for operating temperatures, with higher bandgaps having advantages under higher-temperature operating conditions. We present a simple comparative soiling-temperature model with experimental collaborative data to address the following question: What is the controlling parameter of the combination of soiling spectral effects and temperature on lower- and higher-bandgap module technologies? Temperature coefficients are measured for groups of modules for the four technologies having bandgaps ranging from 1.1 to 1.7 eV. Additional optical absorption for the soiling layers in the range of 300 nm to ~600 nm is confirmed by transmission measurements. The data from our soiling monitoring stations indicate that these potential spectral effects are based on consistent differences in soiling ratios and soiling rates. Some differences between the model predications and experimental observations are discussed. This paper reports temperature and soiling regions of “best-of-class” performances for these four commercial PV technologies in this climate region based upon the two competing parameters.

The increasing technical and economic viability of photovoltaic solar energy technologies includes modules with organic photovoltaic (OPV) cells, which have shown significant efficiency increases, reaching 20% for research devices. This study investigated the photodegradation and associated loss mechanisms in OPV devices under tropical conditions in Brazil. The electrical and optical characteristics of the modules were correlated with chemical and structural changes when exposed to sunlight. Electrical parameters were monitored over time on external test benches and measured in solar simulators, while changes in the optical transmission and absorption of the films were analyzed. Scanning electron microscopy, energy-dispersive spectroscopy, and Fourier-transform infrared spectroscopy were used to study the physical and chemical properties of the materials. We found that photodegradation causes bound breakage in the active layer, altering the carbon structure and consequently reducing the module’s output power. The primary reasons for the activation and progression of this mechanism are high temperature and elevated solar irradiance. Therefore, we demonstrate that understanding these mechanisms is essential for the development of more sustainable OPVs in tropical climates.

O acúmulo de sujidades sobre módulos fotovoltaicos (FV) induz na redução do desempenho destes dispositivos, podendo ser ainda mais agravante em regiões consideradas atrativas para a aplicação dessa tecnologia, onde a irradiância apresenta elevados índices ao longo do ano, porém sobre predominância de clima seco e árido propício para a deposição de sujidades. Os efeitos do acúmulo de sujeira no desempenho dos módulos FV são específicos para cada localidade, uma vez que o comportamento da deposição e a composição físico-química dos contaminantes são influenciados por um conjunto de variáveis específicas do local de instalação dos módulos fotovoltaicos. Neste cenário, este artigo apresenta uma metodologia para quantificar a taxa de sujidade (SRatio) e a taxa de sujeira (SRate) em módulos FV de telureto de cádmio (CdTe) e silício policristalino (p-Si) através de medições realizadas em estações de monitoramento instaladas em diferentes zonas climáticas do Brasil. Os resultados indicaram: (1) Belo Horizonte/MG (latitude - 19,92°, longitude -43,99°), um SRatio médio para o período de análise de 0,94 para telureto de cádmio (CdTe) e 0,92 para silício policristalino (p-Si); (2) Porto Alegre/RS, (Latitude -30,05 °, Longitude -51,17 °), um SRatio em torno de 0,97 e 0,98 para as tecnologias CdTe e p-Si, respectivamente; e (3) Brotas de Macaúbas/BA (Latitude -11,99°, Longitude -42,62°), SRatio de 0,99 e 0,95 para as tecnologias CdTe e p-Si, respectivamente. A partir das características do SRatio, os dados do período seco foram utilizados para estimar o SRate através do estimador Theil-Sen, resultando em valores médios de -0,20%/dia para o CdTe e -0,14%/dia para Belo Horizonte/MG. O maior SRate para tecnologia CdTe pode ser justificado devido a diferença nas respostas espectrais das duas tecnologias FV, pois a sujeira tem um impacto maior nas tecnologias fotovoltaicas de menor comprimento de onda.