The photovoltaic effect: How solar cells generate electricity

Photovoltaics (PV for short) is the industry term describing both the technology and equipment used to capture electrical energy from sunlight. A PV module (or panel) can be thought of as a direct current (DC) generator powered by the sun. When light photons of sufficient energy strike a solar cell, they knock electrons free from the (usually) silicon atoms in the crystal structure of the cell. When the module is connected to a closed external circuit (e.g., to charge a battery or directly feed a DC load), electrical current is the result. The moving electrons provide power to the circuit and load, then return to the other side of the solar cell to start the process over again.

The voltage output from a single crystalline solar cell is about 0.5V with an amperage output that is directly proportional to the cell’s surface area. Within a typical 12V nominal solar module, 36-72 cells are wired in series (+ to -) to produce a DC output of about 17V at Peak power voltage. Such modules can then be interconnected in series and/or parallel (+ to +, - to -) with other modules to form a complete solar array of a given voltage and amperage output.