a collector module 1 with collector tubes 2 is shown in fig1 . the collector tubes 2 have connectors 40 connected individually with each other at their head ends and foot caps 80 connected individually with each other at their foot ends . an enlarged view of a portion of the collector module is shown in fig2 in its head region , so that the connectors 40 , described in detail in the following , can be seen more clearly . a connector 40 has a cup - shaped receiving part 41 , in which the collector tube 2 is glued . in the direction of the collector device , which here is shown as a collector manifold 20 , a u - shaped connecting part 45 connects to the collector tube . the u - shaped connecting part 45 embraces the collector manifold 20 and cooperates with a suitable sealing element 60 . as shown in fig2 the width b of the u - shaped connecting part 45 is clearly less than the diameter d of the cup - shaped receiving part 41 , so that a free space remains between two neighboring connecting parts 45 . thus a collector manifold connection can be arranged there without noteworthy enlargement of the tube spacing along the collector manifold 20 . a cross - sectional view through the collector tube 2 with connector 40 , collector manifold 20 and foot caps 80 in place is shown in fig3 . the collector tube 2 comprises a tubular jacket 3 , which is connected by fusion with an inner absorber tube 4 by connecting wall 5 . this structure for the collector tube 2 is known in the prior art . the interior of the absorber tube 4 is thus accessible at the opening 6 , so that a coaxial tube 7 and a nipple 24 can be inserted therein . the collector manifold 20 comprises an outer tubular wall 21 and a coaxial interior tube 22 , so that two chambers c i and c o for inflow and outflow of heat transfer medium are formed in it . several nipples 24 are arranged on this collector manifold 20 . one of these nipples 24 is shown in fig3 which extends into the absorber tube 4 , where a seal is formed by means of two o - rings 25 arranged on the outside of the nipple 24 . furthermore the coaxial tube 7 , which at one end sits tightly on the opening of the inner tube 22 and at the other end is braced on a spring 8 arranged in the absorber tube 4 , is inserted in the interior of the nipple . thus the coaxial tube 7 is securely held in place . the heat transfer medium flows in the direction of the arrow 26 through the coaxial tube 7 , reverses direction in the vicinity of the spring 8 and flows in the direction of the arrow 27 to the outer end of the coaxial tube again into the collector manifold 20 . the connector 40 has a cup - shaped receiving part 41 , in which the tubular jacket 3 is glued by means of a layer 9 of adhesive . the adhesive layer 9 does not extend in this embodiment over the entire inner surface of the cup - shaped receiving part 41 , because the tubular jacket 3 has a circumferential bead 10 and an adhesive layer in this region is sufficient in order to guarantee a secure attachment of the collector tube 2 . an opening 43 in the bottom wall 42 of the cup - shaped receiving part 41 is provided for receiving the nipple 24 . on the end opposite from the mouth of the cup - shaped receiving part 41 the u - shaped connecting part 45 is provided . the u - shaped connecting part 45 has two arms 46 a , 46 b , which engage or embrace the collector manifold 20 like a pair of jaws . respective locking elements 47 a , 47 b are provided on the corresponding free ends of both arms 46 a , 46 b . in the embodiment shown in the drawing these locking elements are tongues and cooperate with corresponding locking elements 62 a , 62 b on the respective legs 61 a , 61 b of the sealing element 60 . these latter locking elements 62 a , 62 b are grooves . the tongues and grooves extend longitudinally in a longitudinal direction l s of the collector manifold . a handle 63 is arranged on the exposed outer wall of the sealing element 60 . the sealing element 60 , formed like a slider , can be pushed in the longitudinal direction l s of the collector manifold by means of the handle 63 , in order to release or unlock it so that the collector pipe 2 together with the connector 40 can be removed from the nipple 24 and the collector manifold 20 . the foot caps 80 are arranged on the opposite end of the collector tube 2 . they can comprise a similar cup - shaped receiving part , in principle . the collector tube 2 and / or the tubular jacket 3 of the collector tube 2 is ( or are ) glued in this foot cap 90 with an adhesive layer 81 . the foot cap 80 has a base 82 at its lower end . the base 82 has a retaining element 88 , which can be used to attach the collector module to a roof . an outlet opening 87 is provided in the lower curved region of the foot cap wall , so that rain water collecting between the collector tube 2 and the foot cap 80 can eventually run away unhindered . this is especially advantageous when the collector module is mounted on a slanting roof in an inclined orientation . a perspective view of a connector 40 is shown in fig4 . the cup - shaped receiving part 41 has locking elements in the form of grooves and tongues 50 a , 50 b on opposite side walls 48 and 49 arranged side - by - side in the longitudinal direction of the collector manifold 20 . both side walls 48 and 49 are plane parallel . as shown in fig2 neighboring side walls 48 and 49 of two neighboring cup - shaped receiving element 41 bear directly on each other , so that the tongues of one of the adjacent side walls engage in the grooves of the other adjacent side wall . thus the connectors 40 are locked with each other and form a stable arrangement . in the transition region between the cup - shaped receiving part 41 and the u - shaped connecting part 45 a roof - attaching element 70 in the form of a ring element with a through - going opening 71 is provided ( see fig4 ). the through - going opening 71 extends perpendicular to the longitudinal axis l c of the connector 40 , so that a bolt or similar attaching element can be inserted through it and thus facilitate attachment to a roof . an additional roof - attaching element 70 can be arranged on the opposite side , but it is usually sufficient to provide one of these roof - attaching elements 70 for each connector 40 . locking elements 47 a , 47 b are arranged on both arms 46 a , 47 b of the u - shaped connecting part 45 , which comprise tongues in the embodiment shown in the drawing . the associated sealing element 60 is similarly curved and has two legs 61 a , 61 b on whose outer sides two grooves 62 a , 62 b are arranged as respective locking elements , in which the corresponding locking elements 47 a , 47 b of the u - shape connecting part 45 engage . thus it is formed like a slider , which can be slid in the longitudinal direction of the collector manifold 20 , in order to release the attachment of the connector 40 from the collector manifold 20 . for this purpose a handle 63 is preferably formed on the outer side . in fig5 a cross - section through a connector 40 is illustrated . [ 0051 ] fig6 shows the underside of a collector module 1 in a cutaway view . respective bolts 72 are inserted through the through - going holes 71 of the roof - attaching element 70 of two connectors 40 , which are screwed into a l - shaped section 73 . this l - shaped section 73 bears on a bar 74 , which extends parallel to the longitudinal direction of the collector manifold 20 , and is rigidly attached to it be screwing . when two adjacent collector modules are attached by this l - shaped section 73 , they can shift or slide with respect to each other in collector connection 30 during thermal expansion of the collector manifolds 20 . [ 0052 ] fig7 is a top or plan view of the arrangement shown in fig6 . a collector tube 2 together with a roof - attaching device is shown in fig8 . a bolt 72 is fixed in a through - going opening 71 and is screwed into the l - shaped section 73 . this section 73 bears on the bar 74 . the short leg bears on the outer side of the bar 74 and forms a stop . on the foot ends a u - shaped curved bar 75 is provided , on which the foot caps 80 are mounted with their bases 88 . the bar 75 is attached to another bar 74 . in this type of roof attachment the collector tube 2 is held under tension between the bars , in fig9 a perspective view of the bottom side of a foot cap 80 is shown . the foot caps have two plane - parallel outer walls 83 and 84 opposite each other , on which locking elements 85 and 86 in the form of respective tongues and grooves are arranged . thus a suitable arrangement like the arrangement in the case of the cup - shaped receiving part 41 results so that connection with neighboring foot caps 80 is possible . a base 82 is formed on the underside , which can be connected with a u - shaped bar 75 by means of a plate - shaped retaining element 88 . the outlet opening 87 is formed on the rear lower region , which has already been illustrated in connection with fig3 and in fig1 . the collector connection 30 of two collector tubes 20 , which are inserted in each other , is shown in fig1 . the connection 30 is sealed by two o - rings 31 . in fig1 an additional embodiment of a connector 40 is shown , which is different from the embodiment shown in fig4 . the sealing element 60 is pivotally connected at a free end of the lower arm 46 b by means of a hinge 64 . a locking element 47 a is arranged on the upper arm 46 a , which locks with the corresponding locking element 61 a on folding the sealing element 60 and thus takes the closed position shown in fig1 b . the disclosure in german patent application 102 12 977 . 0 of mar . 19 , 2002 is incorporated here by reference . this german patent application describes the invention described hereinabove and claimed in the claims appended hereinbelow and provides the basis for a claim of priority for the instant invention under 35 u . s . c . 119 . while the invention has been illustrated and described as embodied in a collector module , it is not intended to be limited to the details shown , since various modifications and changes may be made without departing in any way from the spirit of the present invention . without further analysis , the foregoing will so fully reveal the gist of the present invention that others can , by applying current knowledge , readily adapt it for various applications without omitting features that , from the standpoint of prior art , fairly constitute essential characteristics of the generic or specific aspects of this invention . what is claimed is new and is set forth in the following appended claims .