Grid
Tie system – these systems are very intelligent, usually
bigger systems, and a Battery backup does not form part of
the greater system.
These
systems are usually not practical for homes/dwelling but
more for offices - which have only day-time occupancy.
These systems are Grid-tied in such a way that whenever
photovoltaic power is available, it will use that power as
first priority, but when no photovoltaic power is available,
it is then drawn from Eskom.
The
Solar Array on these systems is usually linked to the rating
of the inverter itself. E.G. a 3KW inverter will have a 3kW
solar array. Power from the alternative source is thus only
available when the sun is shining, or with certain wind
turbine systems, when the wind is blowing.
Inverters
used here are typically SMA, Victron and for Big systems of
100KW upwards - Hitachi/ Siemens.
It
would not make sense to have such a system with a 3kW panel
array when the average power usage for instance is only 1KW
per hour, as the additional energy is then simply not used
and thus wasted (unless it can be fed back, or sold back, to
the Grid). On bigger system however, although not legislated
in SA yet (but in progress) , that additional power can be
sold back to the grid. (In contrast, the Hybrid power
backup system will store the extra energy in the battery
bank for use at a later stage).
The Understanding of these differences between the various
systems is very important in order to understand the
respective cost implication associated with each system.