The effect of the total solar eclipse on the performance of the solar concentrator is studied on the Big Solar Furnace (BSF) in the Institute of Material Science Scientific -Production Association "Physics-Sun", Academy of Sciences of Uzbekistan at Parkent of Uzbekistan during the partial solar eclipse of August 1, 2008. It is found that the solar radiation decreased dramatically in the first half an hour from 500 W/m2 at 15:00 to a few Watts per squared meters at 15:35, while it began to increase gradually until reaching about 370 W/m2 at 17:08. The distribution of the heat in the focus of the BSF is tested by measuring the heating power of radiation concentrated by the furnace during that eclipse. Heat energy distribution contours are obtained in the mode of tracking the trajectory of the sun during the eclipse. The divergence of the focus during the eclipse of the BSF doesn't exist and the structure of the spot has no significant change.