The solar array is made up of a number of modules (or panels), each consisting of multiple solar cells connected together in series. It is connected to an inverter which can be situated either in the loft or next to your consumer unit. The inverter is the brains behind the system and converts the DC electrical power from the solar modules into AC electricity to power your household appliances.
The inverter constantly monitors the mains voltage and then when possible increases the inverter output voltage to be higher than the mains, this means that any appliances you have on (e.g your lights, TV, washing machine, hair dryer etc) will draw their electricity preferentially from the solar array. This will directly reduce your electricity bill.
If the system isn't producing enough power (e.g. at night or over cast conditions) then your electricity is imported as usual from the National Grid. If the energy isn't used on site then it will be exported to the National Grid. The whole system is completely automatic and requires no intervention.
The system will involve having two additional meters: one records how much you export (the EXPORT meter) and the other measures how much you generate in total.
The diagram on the left demonstrates how Solar PV is connected to the grid.