Photovoltaic module having printed PV cells connected in series by printed conductors
A PV module is formed having an array of PV cells, where the cells are separated by gaps. Each cell contains an array of small silicon sphere diodes (10-300 microns in diameter) connected in parallel. The diodes and conductor layers may be patterned by printing. A continuous metal substrate supports the diodes and conductor layers in all the cells. A dielectric substrate is laminated to the metal substrate. Trenches are then formed by laser ablation around the cells to sever the metal substrate to form electrically isolated PV cells. A metallization step is then performed to connect the cells in series to increase the voltage output of the PV module. An electrically isolated bypass diode for each cell is also formed by the trenching step. The metallization step connects the bypass diode and its associated cell in a reverse-parallel relationship.
1. A solar cell structure comprising:
a monolayer of microscopic diode spheres on a first substrate as a first diode layer, the diode spheres having a top surface portion of a first conductivity type, for being exposed to the sun to generate electricity, and having a bottom surface portion of a second conductivity type;
a first conductor layer electrically contacting the bottom surface portion;
a second conductor layer electrically contacting the top surface portion;
first gaps separating areas of the first diode layer, the first conductor layer, and the second conductor layer to form a plurality of electrically isolated cells;
second gaps within each of the cells segmenting a portion of each of the cells to electrically isolate a remaining portion of the associated cell from its segmented cell portion;
a third conductor layer within each of the cells connecting the first conductor layer within each of the remaining portions of the associated cell to the second conductor layer of its segmented cell portion;
a fourth conductor layer within each of the cells connecting the first conductor layer within each of the segmented cell portions to the second conductor layer of its associated remaining portion, such that the third conductor and the fourth conductor cause the segmented cell portion of each cell to be a bypass diode for its associated cell, wherein the bypass diode and its associated remaining portion are connected in a reverse-parallel relationship; and
a fifth conductor interconnecting at least some of the cells in series by electrically connecting the first conductor layer of one cell to the second conductor layer of an adjacent cell.
2. The structure of claim 1 wherein the diode spheres comprise microscopic diode spheres, wherein each of the cells comprises a subset of the plurality of diode spheres connected in parallel.
3. The structure of claim 1 wherein the first conductor layer is over a conductive substrate, wherein the conductive substrate is affixed to a dielectric substrate, and wherein the gaps extend down to the dielectric substrate.
4. The structure of claim 1 wherein the gaps comprise trenches formed by laser ablation.
5. The structure of claim 1 wherein the first conductor layer is patterned to correspond to an array of the cells.
6. The structure of claim 1 wherein an edge of the first conductor layer extends out from each of the cells to gain electrical access to the bottom surface portion of the diodes.
7. The structure of claim 1 wherein the second conductor layer comprises a transparent conductor material.
8. The structure of claim 1 wherein the diode spheres comprise microscopic silicon spheres.
9. The structure of claim 1 wherein the cells are connected in series in a serpentine pattern.