Photovoltaic systems

Photovoltaic systems are divided into two categories: Stand-Alone and Grid-Connected.

The Grid-Connected systems are installed in buildings where the electricity supply is already present; These systems produce energy during the day and supply the national grid with any excess energy produced, whereas during the night, when the photovoltaic system cannot produce energy, the national grid supplies the user with energy.  A special type of meter is installed to measure the energy consumed  and therefore the amount of energy supplied by the grid as well as the amount supplied to the grid by the user's photovoltaic system. The difference between the KWh produced and supplied  and the KWh actually consumed determines the credit or debit  of the energy supplier. 

The Stand-Alone systems are isolated and the buildings with this type of system installed do not need any other supplier of electricity. They are completely independent. Of course, these systems need other components besides the solar panels, which are:

Accumulators: More commonly known as "batteries", but fitted with a special piece of equipment for the allowing for the recharge to be controlled and regulated.

Inverter: A photovoltaic system produces direct current, but if the charges work in alternated current it's necessary to install an inverter which is able to transform the the direct current in alternate current.

Generator: A motor with an alternator installed on its axis. It provides supplementary energy by recharging the battery in the event that the energy consumption is much higher than the energy produced by the photovoltaic system.