Photovoltaic (Pv) Cells:

Various types of silicon diodes can produce dc all by themselves if adequate IR, visible-light, or UV energy strikes their p-n junctions. This is termed as the photovoltaic effect, and it is the theory by which solar cells work.

The Photovoltaic (PV) cells contain large p-n junction surface area (the figure is as shown below. This maximizes the quantity of energy which strikes the junction after passing through the thin layer of p-type material. The single silicon PV cell generates around 0.6 V dc in direct sunlight under no-load circumstances (that is, whenever there is nothing connected to it which will draw current from it). The maximum quantity of current which a PV cell can deliver depends on the surface region of the p-n junction.

Figure: Simply cross-sectional drawing of a photovoltaic (PV) cell.

The Silicon PV cells are connected in series-parallel combinations to give solar power for solid-state electronic devices like portable radios. A large assembly of these cells constitutes a solar panel. The dc voltages of the cells add whenever they are connected in series. The typical solar battery sup- plies 6, 9, or 12 V dc. Whenever two or more matching sets of series-connected then PV cells are connected in parallel, the output voltage is not raised, though the solar battery becomes capable of delivering more current. The current delivering capacity rises in direct proportion to the number of sets of series-connected cells which are connected in parallel.

PROBLEM:

How many silicon PV cells does it require to make a 13.8-V solar battery?

SOLUTION:

The PV cells should be connected in series therefore the voltages add. Each silicon PV cell generates around 0.6 V dc. Hence, in order to acquire 13.8 V dc from the solar battery, we should connect 13.8/0.6, or 23, of the PV cells in series.