A photovoltaic module comprising: a base plate (110, 210, 310, 610, 710, 810); a cell string (100, 200, 300, 600, 700, 800) disposed on the base plate (110, 210, 310, 610, 710, 810), the cell string (100, 200, 300, 600, 700, 800) having a first surface facing away from the base plate (110, 210, 310, 610, 710, 810), a second surface opposite to the first surface and facing the base plate, and a side surface between the first and second surfaces; a cover plate (120, 220, 320, 620, 720, 820) over the first surface of the cell string (100, 200, 300, 600, 700, 800); a first packaging layer (130, 230, 330, 630, 730, 830), located between the base plate (110, 210, 310, 610, 710, 810) and the cover plate (120, 220, 320, 620, 720, 820) and surrounding and facing the side surface of the cell string (100, 200, 300, 600, 700, 800), wherein the first packaging layer (130, 230, 330, 630, 730, 830), the base plate (110, 210, 310, 610, 710, 810) and the cover plate (120, 220, 320, 620, 720, 820) define a first sealed space housing the cell string; a plurality of moisture detection layers, arranged in the first sealed space and spaced from each other, wherein the plurality of moisture detection layers are arranged on and across the first surface of the cell string (100, 200, 300, 600, 700, 800) and between the cell string (100, 200, 300, 600, 700, 800) and the first packaging layer (130, 230, 330, 630, 730, 830), and the plurality of moisture detection layers are adaptive to provide response information indicating whether there is moisture in the first sealed space; and a second packaging layer filling the first sealed space thereby embedding the cell string (100, 200, 300, 600, 700, 800) and the plurality of moisture detection layers, wherein a material of the second packaging layer is same as a material of the first packaging layer. a base plate (110, 210, 310, 610, 710, 810); a cell string (100, 200, 300, 600, 700, 800) disposed on the base plate (110, 210, 310, 610, 710, 810), the cell string (100, 200, 300, 600, 700, 800) having a first surface facing away from the base plate (110, 210, 310, 610, 710, 810), a second surface opposite to the first surface and facing the base plate, and a side surface between the first and second surfaces; a cover plate (120, 220, 320, 620, 720, 820) over the first surface of the cell string (100, 200, 300, 600, 700, 800); a first packaging layer (130, 230, 330, 630, 730, 830), located between the base plate (110, 210, 310, 610, 710, 810) and the cover plate (120, 220, 320, 620, 720, 820) and surrounding and facing the side surface of the cell string (100, 200, 300, 600, 700, 800), wherein the first packaging layer (130, 230, 330, 630, 730, 830), the base plate (110, 210, 310, 610, 710, 810) and the cover plate (120, 220, 320, 620, 720, 820) define a first sealed space housing the cell string; a plurality of moisture detection layers, arranged in the first sealed space and spaced from each other, wherein the plurality of moisture detection layers are arranged on and across the first surface of the cell string (100, 200, 300, 600, 700, 800) and between the cell string (100, 200, 300, 600, 700, 800) and the first packaging layer (130, 230, 330, 630, 730, 830), and the plurality of moisture detection layers are adaptive to provide response information indicating whether there is moisture in the first sealed space; and a second packaging layer filling the first sealed space thereby embedding the cell string (100, 200, 300, 600, 700, 800) and the plurality of moisture detection layers, wherein a material of the second packaging layer is same as a material of the first packaging layer.