Forming front metal contact on solar cell with enhanced resistance to stress
System and method of providing a photovoltaic (PV) cell having a cushion layer to alleviate stress impact between a front metal contact and a thin film PV layer. A cushion layer is disposed between an extraction electrode and a photovoltaic (PV) surface. The cushion layer is made of a nonconductive material and has a plurality of vias filled with a conductive material to provide electrical continuity between the bus bar and the PV layer. The cushion layer may be made of a flexible material preferably with rigidity that matches the substrate. Thus, the cushion layer can effectively protect the PV layer from physical damage due to tactile contact with the front metal contact.
1. A photovoltaic module, comprising:
an array of photovoltaic cells configured to convert light energy to electrical energy, wherein each photovoltaic cell in the array of photovoltaic cells comprises:
a substrate;
a photovoltaic layer disposed over the substrate;
a back metal layer disposed between the substrate and the photovoltaic layer;
an interconnect grid disposed on top of the photovoltaic layer and configured to conduct electrical current originated from the photovoltaic layer to external circuitry, wherein the interconnect grid comprises discrete finger electrodes and an extraction electrode coupled to the discrete finger electrodes;
a front metal contact disposed on top of the interconnect grid;
an encapsulation layer disposed on top of the front metal contact; and
a cushion layer disposed between the front metal contact and the interconnect grid to protect the photovoltaic cell from physical damage due to tactile contact with the front metal contact, the cushion layer being formed of a flexible material that is a same material as the substrate, and a rigidity of the cushion layer being less than a rigidity of the front metal contact,
wherein a plurality of vias filled with a conductive material are disposed within the cushion layer between the interconnect grid and the front metal contact such that each respective via is aligned with and directly contacts a respective discrete finger electrode of the interconnect grid, wherein the front metal contact and the cushion layer wrap around an edge of the photovoltaic cell,
wherein the photovoltaic cells in the array are electrically connected.
2. The photovoltaic module as described in claim 1 , wherein the back metal layer of one of the photovoltaic cells in the array is electrically connected to the interconnect grid of another photovoltaic cell in the array.
3. The photovoltaic module as described in claim 1 , wherein the cushion layer comprises a flexible polymer material.
4. The photovoltaic module as described in claim 3 , wherein the flexible polymer material comprises polyethylene terephthalate (PET) combined with pressure sensitive adhesive (PSA).
5. The photovoltaic module as described in claim 1 , wherein:
the substrate comprises a polymer material,
the front metal contact comprises Cu, and
the photovoltaic layer comprises thin film GaAs.
6. The photovoltaic module as described in claim 1 , wherein the photovoltaic layer is less than 10 μm in thickness and comprises a GaAs layer.
7. The photovoltaic module as described in claim 1 , wherein the front metal contact is thicker than the photovoltaic layer.
8. The photovoltaic module as described in claim 1 , wherein the front metal contact is 50 μm in thickness and the photovoltaic layer is less than 10 μm in thickness.