be provided by the PV (especially a

be provided by the PV (especially at night!) it is imported from the grid.
In other words the PV system and grid act in harmony and there is an
automatic, seamless back - and - forth fl ow of electricity according to sunlight
conditions and the electricity demand.
In more detail the various items numbered 1 – 8 in the fi gure have the following
functions:
1. PV combiner unit. This acts as a junction box connecting the
modules in the desired confi guration.
2. Protection unit. This unit houses a DC switch to isolate the PV array
and antisurge devices to protect against lightning. Alternatively,
these functions may be incorporated into units 1 or 3.
3. Inverter. At the heart of the grid - connection system, the inverter
extracts as much DC power as possible from the PV array and converts
it into AC power at the right voltage and frequency for feeding