A photovoltaic device (1;1';1") comprising: • a solar cell unit including: - a working electrode comprising a porous light-absorbing layer arranged at a top side of the solar cell unit, - a first conducting layer for extracting photo-generated electrons from the light-absorbing layer , wherein the light-absorbing layer is arranged on top of the first conducting layer , - a porous substrate made of an insulating material, wherein the first conducting layer is formed on one side of the porous substrate , - a counter electrode including a second conducting layer arranged at a bottom side of the solar cell unit, wherein the second conducting layer is formed on an opposite side of the porous substrate , and - a conducting medium for transferring charges between the second conducting layer and the light-absorbing layer , • a first conductor (7; 7b) in electrical contact with the first conducting layer , • a second conductor (8; 8a, 8b; 8c) in electrical contact with the second conducting layer , and an encapsulation encapsulating the solar cell unit and comprising an at least partly transparent top sheet covering the top side of the solar cell unit and a bottom sheet covering the bottom side of the solar cell unit, wherein the second conductor (8; 8a, 8b; 8c) is arranged between the second conducting layer and the bottom sheet of the encapsulation at the bottom side of the solar cell unit , characterised in that the first conductor is arranged between the porous substrate and the bottom sheet at the bottom side of the solar cell unit , the first conductor is electrically insulated from the second conducting layer , and a part of the porous substrate comprises conducting material disposed between the first conductor (7;7b and the first conducting layer to provide electrical contact between the first conductor and the first conducting layer. • a solar cell unit including: - a working electrode comprising a porous light-absorbing layer arranged at a top side of the solar cell unit, - a first conducting layer for extracting photo-generated electrons from the light-absorbing layer , wherein the light-absorbing layer is arranged on top of the first conducting layer , - a porous substrate made of an insulating material, wherein the first conducting layer is formed on one side of the porous substrate , - a counter electrode including a second conducting layer arranged at a bottom side of the solar cell unit, wherein the second conducting layer is formed on an opposite side of the porous substrate , and - a conducting medium for transferring charges between the second conducting layer and the light-absorbing layer , - a working electrode comprising a porous light-absorbing layer arranged at a top side of the solar cell unit, - a first conducting layer for extracting photo-generated electrons from the light-absorbing layer , wherein the light-absorbing layer is arranged on top of the first conducting layer , - a porous substrate made of an insulating material, wherein the first conducting layer is formed on one side of the porous substrate , - a counter electrode including a second conducting layer arranged at a bottom side of the solar cell unit, wherein the second conducting layer is formed on an opposite side of the porous substrate , and - a conducting medium for transferring charges between the second conducting layer and the light-absorbing layer , • a first conductor (7; 7b) in electrical contact with the first conducting layer , • a second conductor (8; 8a, 8b; 8c) in electrical contact with the second conducting layer , and <EOS>