Quoted from:Chegaar M ,  Chibani A . Global solar radiation estimation in Algeria[J]. Energy Conversion and Management, 2001, 42(8):967–973.https://www.sci-hub.ren/10.1016/s0196-8904(00)00105-9

Two models for estimating monthly average daily global radiation on a horizontal surface have been applied to four different locations. The first one is an empirical model, originally formulated by Barbaro et al.Some modifications have been suggested. The second one is a regression equation of the Angstrom type. The agreement between the measured and the computed values is remarkable, and the models are both recommended for use in Algeria and in any location with similar climatic parameters.

Introduction

Solar energy occupies one of the most important places among the various possible alternativeenergy sources. An accurate knowledge of the solar radiation distribution at a particular geo-graphical location is of vital importance for the development of many solar energy devices and forestimates of their performances. Unfortunately, for many developing countries，solar radiationmeasurements are not easily available because of not being able to afford the measurementequipment and techniques involved. Therefore, it is rather important to elaborate methods toestimate the solar radiation on the basis of more readily available meteorological data.

Chegaar and Chibani have proposed the following linear relationship between 𝐻/𝐻0 and 𝑆/𝑆0 for estimating global solar radiation on horizontal surface:

\( 𝐻/𝐻_0 = 0.2424 + 0.5014 𝑆/𝑆_0 , \)

The monthly average daily global radiation incident on a horizontal surface has been estimatedusing two empirical models. The first one was originally formulated by Barbaro et al. andmodified by the authors to make it fit some Algerian meteorological stations. The formula re-quires only the sunshine duration and the noon solar altitude of the sun.Appropriate zone pa-rameters have been determined, K = 14.1 for Algiers and Oran, K = 14.6 for Beni Abbas andK = 17.3 for Tamanrasset. It is possible to determine other zone parameters by extending thismodel to other meteorological stations. The second one is a linear regression of the Angstromtype.The values of the constants a and b change from place to place according to the climaticcharacteristics. The agreement between the measured and the estimated values is remarkable, andboth models are recommended for use in any location in Algeria or stations with similar climate.