Empirical correlations as a means for estimating monthly average daily global radiation: A critical overview

Edward Halawa, AmirHosein GhaffarianHoseini, Danny Hin Wa Li

    Research output: Contribution to journalArticlepeer-review


    In regions where solar energy is abundant, solar energy can play a vital role in attaining energy sustainability. Sizing solar energy systems requires the availability of solar radiation data on horizontal surface which can then be used to calculate solar radiation intensity on any tilted surface using appropriate conversion factors or formula. In many parts of the world, especially in developing countries, such data is not readily available. Many researchers have found that monthly average daily value of global solar radiation on horizontal surface can be estimated when meteorological parameters such as duration of sunshine, number of rainy days, relative humidity, etc. are available. Many empirical correlations have been developed based on this approach. The development of such a correlation has been made possible through the availability of solar and other meteorological data required for their validation. This paper presents a review on the existing empirical correlations and critically looks at the practicality of such correlations. This raises the question on the appropriateness of the past and present approaches adopted by researchers in this field. The paper also discusses various related aspects and proposes new directions for future research.
    Original languageEnglish
    Pages (from-to)149-153
    Number of pages5
    JournalRenewable Energy
    Publication statusPublished - Dec 2014


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