The basic principles of solar PV can be explained quickly and simply:
Solar PV panels are designed to be directed towards the suns natural light, this light energy is absorbed and changed in to electricity. This electricity is sent from the panels through DC electric cabling down to an inverter, the inverter converts the electricity from DC to AC (the type used in your home).
The AC electricity then goes from the inverter and down to the consumer unit within your home, the electricity takes the path of least resistance and therefore goes to any electrical demand within the property, any excess goes down the wires to the National Grid.
Solar PV often will now have battery storage added to it, this basically means that the electricity produced from the solar panels that is not used in the home when it is made, can then be stored in batteries rather than going out to the national grid.