Extreme overirradiance events in São Paulo, Brazil

Almeida, Marcelo Pinho; Zilles, Roberto; Lorenzo, E.

doi:10.1016/j.solener.2014.09.012

Cited by 36 publications

(15 citation statements)

References 14 publications

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“…In figure 1, one can notice a significant number of occurrences of overirradiance, that is to say a clear sky index above 1. These cloud enhancement events can be observed everywhere in the world (Almeida et al, 2014). This phenomenon is more visible when using short time scales as in our study with 10-min mean of solar irradiance.…”

Section: Datasupporting

confidence: 57%

Probabilistic forecasting of the solar irradiance with recursive ARMA and GARCH models

David¹,

Ramahatana²,

Trombe

et al. 2016

Solar Energy

166

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International audienceForecasting of the solar irradiance is a key feature in order to increase the penetration rate of solar energy into the energy grids. Indeed, the anticipation of the fluctuations of the solar renewables allows a better management of the production means of electricity and a better operation of the grid-connected storage systems. If numerous methods for forecasting the mean of the solar irradiance were recently developed, there are only few works dedicated to the evaluation of prediction intervals associated to these point forecasts. Time series of solar irradiance and more specifically of clear sky index show some similarities with that of financial time series. The aim of this paper is to assess the performances of a commonly used combination of two linear models (ARMA and GARCH) in econometrics in order to provide probabilistic forecasts of solar irradiance. In addition, a recursive estimation of the parameters of the models has been set up in order to provide a framework that can be applied easily in an operational context. A comprehensive testing procedure has been used to assess both point forecasts and probabilistic forecasts. Using only the past records of the solar irradiance, the proposed model is able to perform point forecasts as accurately as other methods based on machine learning techniques. Moreover, the recursive ARMA-GARCH model is easier to setup and it gives additional information about the uncertainty of the forecasts. Even if some strong assumption has been made regarding the statistical distribution of the error, the reliability of the probabilistic forecasts stands in the same order of magnitude as other works done in the field of solar forecasting

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Section: Datasupporting

confidence: 57%

Probabilistic forecasting of the solar irradiance with recursive ARMA and GARCH models

David¹,

Ramahatana²,

Trombe

et al. 2016

Solar Energy

166

View full text Add to dashboard Cite

show abstract

“…Cloud-edge and cloud enhancement effects on solar irradiance at ground level have been previously reported in the literature [1]. Figure 3 shows an example with both effects taking place simultaneously at one of the eight ES reported in this paper, and Table 1 shows for the same site all the overirradiance events measured over nearly 2 years.…”

Section: Resultssupporting

confidence: 70%

“…The influence of high operating temperatures, extreme overirradiance events due to cloud-edge and cloud-enhancement effects [1][2][3][4][5][6][7][8], and soiling [9][10][11][12] on the performance of PV power plants is much more extreme in these countries than in the more temperate climates where most of the ∼300 GW of PV operate worldwide [13][14][15][16][17][18][19][20]. The negative temperature coefficient of power of the crystalline silicon and the copper indium gallium diselenide (CIGS) thin-film PV technologies are both in the order of À0.4 to À0.5%/°C, while for the thin-film amorphous silicon and cadmium telluride CdTe PV technologies it is around À0.2%/°C.…”

Section: Introductionmentioning

confidence: 99%

Performance assessment issues in utility-scale photovoltaics in warm and sunny climates

Rüther

Nascimento

Campos

2017

Renew. Energy Environ. Sustain.

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Abstract. With the declining costs of photovoltaics (PV), and the excellent solar energy resource availability in the country, the Brazilian government and the electricity sector have started to evaluate and consider PV as a serious potential contributor to the National electricity mix. Since the late 1990s, Brazilian electrical utilities are required by the National Electrical Energy Regulatory Agency ANEEL to invest 1% of their operational income on R&D. In 2011, ANEEL issued an R&D call dedicated to utility-scale PV. The solar energy research group at Universidade Federal de Santa Catarina (www.fotovoltaica.ufsc.br) has been actively investigating and promoting PV in Brazil, operates since 1997 the first grid-connected, thin-film PV generator in the country. Under the ANEEL R&D call, a 4-year, US$ 20 million project was started in 2012. The project aims at assessing the performance of seven different PV technologies at eight different Evaluation Sites (ES) in Brazil, and also to design, procure, install and monitor the performance of a utility-scale 3 MWp R&D PV power plant, which is located at one of these eight ES. The 3 MWp PV power plant and all the eight ES are fully monitored, with all electrical and environmental parameters measured at 1-s intervals. PV technologies include thin-film amorphous silicon (a-Si), microcrystalline silicon (mc-Si), cadmium telluride (CdTe), copper indium gallium diselenide, mono-and multi-crystalline silicon (c-Si and m-Si), all at fixed tilt, as well as double-axis tracking, concentrated PV using triple-junction InGap/GaAs/Ge at 820 suns concentration. All ES are identical, except for the fixed PV arrays tilt angle, which is equal to the latitude at each site. The 3 MWp R&D PV power plant is co-located at one of the ES sites. Thin-film PV technologies with a low temperature coefficient of power presented superior output performance, and cloud-edge and cloud-enhancement effects of solar irradiance resulted in operational issues that were not previously described in the literature. Inverter Loading Ratios commonly described in the literature (for less sunny sites) led to considerable annual energy losses.

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“…K T can reach much higher, over-unity values because of intense transient effects usually referred to as ''cloud enhancement", ''cloud lensing" or ''overirradiance". Recent investigations under different types of climate (Almeida et al, 2014;Piacentini et al, 2011;Piedehierro et al, 2014;Tapakis and Charalambides, 2014;Yordanov et al, 2015) generally describe these events as transient situations of high sun surrounded by bright clouds. Detection of such events is important in the context of PV applications in particular to correctly size inverters (Luoma et al, 2012) or to characterize ramping effects and their impact on electricity distribution and grid stability (Lave et al, 2015a).…”

Section: Impact Of Surface Albedo and Cloud Enhancementmentioning

confidence: 99%

Extensive worldwide validation and climate sensitivity analysis of direct irradiance predictions from 1-min global irradiance

Gueymard¹,

Ruiz‐Arias

2016

Solar Energy

216

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Extreme overirradiance events in São Paulo, Brazil

Abstract: Phenomena of overirradiance have been pointed all over the World. This note presents the most extreme enhancement event reported in Brazil, which contains an irradiance reading of 1590 W/m 2 measured in Sao Paulo (latitude 23°32'S) at relatively low altitude (760 m a.s.L).

Cited by 36 publications

References 14 publications

Probabilistic forecasting of the solar irradiance with recursive ARMA and GARCH models

Probabilistic forecasting of the solar irradiance with recursive ARMA and GARCH models

Performance assessment issues in utility-scale photovoltaics in warm and sunny climates

Extensive worldwide validation and climate sensitivity analysis of direct irradiance predictions from 1-min global irradiance

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