Short Note Solar radiation climate in Malawi A. Madhlopa * Department of Physics and Biochemical Sciences, Malawi Polytechnic, P/Bag 303, Blantyre 3, Malawi Received 5 March 2003; received in revised form 9 May 2005; accepted 30 August 2005 Available online 30 September 2005 Communicated by: Associate Editor David Renne Abstract Recently, Diabate ´ et al. [Diabate ´, L., Blanc, Ph., Wald, L., 2004. Solar climate in Africa. Solar Energy 76, 733–744] created a map of solar radiation climate in Africa using clearness index for 62 sites. They established a solar climate class II located in Malawi and Madagascar. However, their analysis did not include any irradiation data from a site in Malawi. In this study, the solar radiation climate of Malawi has been studied using long-term global radiation data from a local site. The mean monthly (K tm ) and seasonal (K ts ) daily clearness indices for the site were computed. It is observed that K tm has two maxima in a year (K tm = 0.58 in May and K tm = 0.64 in September), in close conformity with findings of Diabate ´ et al. (2004). Other results are presented and discussed. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Global radiation; Clearness index; Tropical country; Long-term data 1. Introduction The intensity of solar radiation is an important parameter in solar system design, testing and oper- ation. However, this parameter varies with space and time. Consequently, many authors including Kudish et al. (1983), Al-Aruri (1990), Kudish and Ianetz (1996) and Ianetz et al. (2000) have studied solar climates of specific locations or regions for the development of solar technologies and other applications. Some work has also been done on solar radi- ation in Malawi, a tropical country located between latitudes 9°22 0 and 17°3 0 S and longitudes 33°40 0 and 35°55 0 E in Africa. Som (1979) showed that there is great potential for the utilization of solar systems in the country. Zingano (1986) studied the intensity of global radiation for twelve sites, mainly based on the sunshine duration. He found that there are: (a) a general gradient of solar radiation over the country in the north-to-south direction, and (b) local gradi- ents of the mean monthly radiation due to altitude. Zingano (2001) observed that lowlands have the highest values of global solar radiation while up- lands have the lowest in Malawi. Madhlopa (2001) evaluated piecewise polynomial models for estimat- ing diffuse radiation in Malawi. Using data from one site, a new piecewise polynomial correlation was developed for estimating the diffuse fraction 0038-092X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2005.08.007 * Fax: +265 1 670578. E-mail address: amadhlopa@poly.ac.mw Solar Energy 80 (2006) 1055–1057 www.elsevier.com/locate/solener