A solar collector comprising: • a trough-formed reflector, • at least one holder for securing a fluid tube for receiving reflected solar radiation from the reflector to the solar collector, the fluid tube being connected to the solar collector by the at least one holder, wherein the holder is configured to, in an operation mode of the solar collector, partly encircle a circumference of a cross-section of the fluid tube and leave a portion of the circumference un-encircled by the holder, and direct the un-encircled portion to face a reflective surface of the reflector, such that the un-encircled portion is accessible for concentrated solar radiation reflected by the reflective surface, the holder comprising: • a base member adapted to abut the fluid tube, the base member comprising at least one securing means adapted to secure the base member to the solar collector, and • an immobilising member adapted to together with the base member immobilise a centre-line of the fluid tube in the solar collector when the fluid tube abuts the holder, the base member being connected with the immobilising member, such that the base member together with the immobilising member can partly encircle the circumference of the cross-section of the fluid tube and, in the operation mode of the solar collector, form an opening smaller than a diameter of the cross-section of the fluid tube, characterised in that the opening is located asymmetrically in relation to the solar collector's optical plane of symmetry. • a trough-formed reflector, • at least one holder for securing a fluid tube for receiving reflected solar radiation from the reflector to the solar collector, the fluid tube being connected to the solar collector by the at least one holder, wherein the holder is configured to, in an operation mode of the solar collector, partly encircle a circumference of a cross-section of the fluid tube and leave a portion of the circumference un-encircled by the holder, and direct the un-encircled portion to face a reflective surface of the reflector, such that the un-encircled portion is accessible for concentrated solar radiation reflected by the reflective surface, the holder comprising: • a base member adapted to abut the fluid tube, the base member comprising at least one securing means adapted to secure the base member to the solar collector, and • an immobilising member adapted to together with the base member immobilise a centre-line of the fluid tube in the solar collector when the fluid tube abuts the holder, the base member being connected with the immobilising member, such that the base member together with the immobilising member can partly encircle the circumference of the cross-section of the fluid tube and, in the operation mode of the solar collector, form an opening smaller than a diameter of the cross-section of the fluid tube, characterised in that the opening is located asymmetrically in relation to the solar collector's optical plane of symmetry. • a base member adapted to abut the fluid tube, the base member comprising at least one securing means adapted to secure the base member to the solar collector, and • an immobilising member adapted to together with the base member immobilise a centre-line of the fluid tube in the solar collector when the fluid tube abuts the holder,