Estimation of the incident global radiation on tilted surfaces using isotropic models and clearness index

• Autor(a) principal: Souza, Adilson Pacheco de
• Data de Publicação: 2011
• Outros Autores: Escobedo, João Francisco, Dal Pai, Alexandre, Gomes, Eduardo Nardini
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/2804
• topic: angle of inclination; indicative statistical; isotropy; solar irradiation; atmospheric transmission; ângulo de inclinação; indicativos estatísticos; radiação solar; transmissividade atmosférica

The objective of this work was to evaluate the performance of isotropic models estimative of the global radiation on tilted surfaces and to propose estimations based on correlation between the clearness index for horizontal and tilted surfaces, for different sky conditions, in Botucatu, SP, Brazil. The isotropic model proposed by Liu & Jordan, Revfeim, Jimenez & Castro, Koronakis, the Circunsolar theory and the correlation between the clearness index for horizontal and tilted surfaces, for different sky conditions, evaluated tilted surfaces at 12.85o, 22.85o, and 32.85°. Global irradiation database used corresponds to the period from 1998 to 2007, with intervals from 4/1998 to 8/2001 for the surface tilted at 22.85°, from 9/2001 to 2/2003 for the surface tilted at 12.85º and from 1/2004 to 12/2007 for the surface tilted at 32.85°. The performance of the models was analyzed using the statistical indicators mean bias error, root mean square error and d-Wilmott. The models of Liu & Jordan, Koronakis and Revfeim showed the best performance on cloudy days considering all the tilted surfaces. The sky coverage partially diffuse and partially clear with the largest tilted angles showed the highest scattering between estimated and measured values, irrespective of the model. Statistical equations showed good results in monthly average data applications.