The PV generator

This is made up of a group of modules connected in series and placed parallel with each other.

Series-connected modules:

The total current of the module "adapts" to that of the module which generates least current, while the overall voltage is given by the sum of the voltage of the individual module. A group of series-connected modules makes up what is known as a string.

Placing strings of modules parallel with each other

The total current of the photovoltaic generator is given by the sum of the current leaving each string.

The overall voltage of the system is instead equivalent to the voltage generated by an individual string.

Shadow effects

The reduction of the power supply caused by a partial shadowing of the photovoltaic field may not be proportional to the portion of the surface in shadow, but much higher. It is therefore necessary to pay close attention to connections. If, for instance, there is a pole in front of a photovoltaic field, it must be ascertained that the effect of its shadow is only felt by a single string and doesn't intercept a larger quantity of module series, jeopardising the proper functioning of the entire plant. It is like squeezing a hose-pipe and stopping the water flowing through it. The same thing happens with the charges generated by photovoltaic cells by various modules. If a shadow appears on a module, the electrons from that module exposed to the sunlight "find their path obstructed" and cannot reach their "destination"...