Collector element for collecting solar energy

A method for transferring heat from at least one collector element collecting solar radiation, wherein the at least one collector element collecting solar energy is made of metal and includes:

• at least one elongated central ridge comprising at least one internal flow channel for a heat transfer medium,
• first and second elongated side ridges at opposite sides of the at least one central ridge, the first and second side ridges being substantially parallel to the at least one central ridge and forming side edges of the collector element, and
• an elongated depression between each two adjacent ridges, and
• wherein a first flank of the first side ridge comprises a first fastening groove extending along the first flank of the first side ridge substantially parallel to the first side ridge and a second flank of the first side ridge comprises a second fastening groove extending along the second flank of the first side ridge substantially parallel to the first side ridge, whereby at least one substantially solar radiation permeable covering element for covering at least the at least one elongated central ridge of the collector element is to be fastened between the first fastening groove in the first flank of the first side ridge in one collector element and the second fastening groove in the second flank of the first side ridge in an adjacent collector element, and
• wherein the first side ridge comprises at a peak portion thereof a first elongated protrusion extending along the peak portion of the first side ridge and protruding away from the peak portion of the first side ridge,
• wherein the first flank of the first side ridge comprises at a distance from the peak portion a second elongated protrusion extending along the first flank and protruding away from the first flank, whereby the first elongated protrusion at the peak portion of the first side ridge and the second elongated protrusion at the first flank of the first side ridge define the first fastening groove extending along the first flank of the first side ridge for receiving a first side edge of the at least one covering element to be fastened between two adjacent collector elements, and
• wherein the second flank of the first side ridge comprises at a distance from the peak portion a third elongated protrusion extending along the second flank and protruding away from the second flank, whereby the first elongated protrusion at the peak portion of the first side ridge and the third elongated protrusion at the second flank of the first side ridge define the second fastening groove extending along the second flank of the first side ridge for receiving a second side edge of the at least one covering element to be fastened between two adjacent collector elements,
• in which method heat transfer medium is arranged to be circulated through at least one heat transfer medium flow channel arranged in connection with the at least one collector element for transferring heat away from the collector element so as to cool down the collector element.