Solar heat collecting device comprising a plurality of fixed solar heat collectors

A solar heat collecting device comprising

• a plurality of collectors, each having a reflection screen with a pair of spaced parallel longitudinal edges and with an elongated trough of curved cross-sectional configuration extending between said edges,
• said parallel longitudinal edges defining a collector aperture therebetween,
• a longitudinal median plane of said reflection screen being located centrally between said parallel longitudinal edges,
• at least one liquid-heating tube adapted to be connected to a liquid circulation system and having a tube axis disposed in the longitudinal plane,
• said tube being located behind and parallel to said aperture,
• said collectors adapted to be arranged with the tube axis located in vertical planes extending in the North-South direction,
• characterized in that the collectors are fixedly disposed as sub-collectors composed of a set of at least two collectors,
• said collectors each having one longitudinal edge of their screen adjoining the longitudinal edge of the other screen,
• said collectors being of identical construction and arranged to collect solar heat during an associated sub-period of at least two consecutive sub-periods of the solar day,
• each sub-collector containing a primary liquid heating tube and a separate, secondary liquid heating tube parallel to said primary liquid heating tube and connected in series with said primary liquid heating tube in a bottom part of the collector,
• said two tubes, in cross-section, adjoining one another in the direction of depth of the trough formed by said screen and extending, in that direction, from the deepest part of said trough for a joint height which is no greater than approximately one-fourth of the aperture width measured between the longitudinal edges of the screen,
• the reflection screen of each sub-collector having, in cross-section, a curved form such that said screen, disposed in a position in which its longitudinal median plane is directed to the sun halfway the sub-period concerned, during a central period falling within said sub-period and corresponding with an angular range of the position of the sun from -X.degree. to +X.degree. relative to said longitudinal median plane, reflects the sun rays incident upon said screen substantially on to said primary tube, and during shorter time intervals, relative to said central period, each immediately before and immediately after said central period, reflects the sun rays incident upon the screen mainly to the anterior secondary tube, and
• the longitudinal median planes of the two sub-collectors forming the set being angularly off-set relatively to each other through an angle of at least approximately 2X.degree..