The widespread use of microalgae in various fields of human activity including fishery generated a need of highly productive technologies of industrial production of microalgae biomass. In present paper, extreme productivity values of microalgae culturing system were assessed around neighborhoods of the Isfahan City in theory. It will amount to 37.90 g of dry weight (g. d. w.) per 1 m2 of the illuminated reactor surface under condition that efficiency factor of photobiosynthesis equals to 5%. When photobiosynthetic efficiency is 15%, maximum values of productivity will be 113.71 g. d. w. per 1 m2. Productivity of microalgae culturing system for its various orientations relative to the Sun at different photobiosynthetic efficiency was calculated on basis of simple model understandings regarding average caloric content of 1 g.d.w. of microalgae and the daily distribution of solar radiation which arrives at the surface of the Earth. If it is drown a curve of the third order (spline) through the points corresponding to days of the vernal (21 March) and autumnal (21 September) equinoxes and a summer solstice (22 June), the extreme (ideal) value of the yield will be 18.5 kg of dry biomass per square meter of illuminated surface (at photobiosynthetic efficiency of 0.15).