Was found that for an elliptical area with the highest concentration (green elliptic), the absorber length is equal to 0.31 m and the width is 0.21 m, as shown in Fig. 9. The number of pipes (ntub) is adjusted to 32 to maintain the parameter designed area of the absorber. The aperture receiver cavity is produced by the Monte-Carlo method (yellow elliptic), which implies that the absorber is inside of the solar image where the concentration of radiant energy is the highest. Table 1 specifies the cavity receiver and absorber dimensions.