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How do electrical contacts carry current from a solar cell to an external circuit?

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Diagram of a solar cell showing labeled layers, including a front electrical contact grid, antireflection layer, absorber layer, back junction layer, and back electrical contact layer, with arrows indicating light entering and terminals connecting to a circuit. — solar cell A commonly used solar cell structure. In many such cells, the absorber layer and the back junction layer are both made of the same material.

Electrical contacts are essential components that carry electric current out of a solar cell to an external load and back, completing the electric circuit. These contacts are typically made of metal to ensure high conductivity.1

The design of these contacts differs based on their position on the cell:

Front Contact: Located on the face where light enters, this layer is generally arranged in a grid pattern. Because metal is opaque and blocks sunlight, these grid lines are designed to be as thin and widely spaced as possible to minimize light obstruction while still effectively collecting the current produced by the cell.1
Back Contact: This layer covers the entire rear surface of the cell. Unlike the front contact, it faces no restrictions regarding light blockage and functions solely as a highly conductive electrical contact.1

Together, these layers allow the photovoltaic effect to drive electrons through an external circuit, where they can perform useful work.1