Evaluation of global solar radiation from meteorological data in the Sahelian zone of Chad

Sustainable Energy Research

Table 8 Error (%) between the measured and estimated values of extraterrestrial solar radiation (H ₀) of the six cities

Month	Abeche	N’Djamena	Ati	Bokoro	Mongo	Moussoro
January	3.543	4.214	4.491	3.853	4.144	3.839
February	−6.746	−5.517	−5.873	−5.847	−5.58	−6.466
March	−13.475	−11.366	−12.683	−11.673	−11.426	−13.228
April	−17.038	−15	−16.286	−15.295	−15.057	−16.8
May	−17.557	−14.743	−16.802	−15.038	−13.981	−17.321
June	−17.038	−14.183	−16.286	−14.481	−14.24	−16.8
July	−16.771	−13.923	−16.01	−14.221	−13.981	−16.533
August	−16.771	−13.923	−16.01	−14.221	−13.981	−16.533
September	−14.598	−12.5	−13.824	−12.804	−12.559	−14.353
October	−8.011	−6.555	−7.168	−6.879	−6.618	−7.747
November	0.939	1.884	1.854	1.53	1.815	1.228
December	7.227	7.855	8.209	7.482	7.783	7.534
Average	−9.691	−7.813	−8.866	−8.133	−7.807	−9.432