Page 338 - A Comprehensive Guide to Solar Energy Systems

Chapter 16 • Small-Scale PV Systems Used in Domestic Applications 343

FIGURE 16.9 Grid-connected current source inverter with feed forward control and ideal current waveforms.

Although the existing PV system topologies can offer acceptable solutions at relatively
higher conversion efficiency for residential applications, the developments in power elec-
tronics are likely to offer step changes while addressing the conversion efficiency and protec-
tion of PV modules at the cell level. Due to the advances, there are now opportunity for MPPT
at the most localized PV cell level. This reduces power and voltage levels and also the size of
both active (switches) and passive elements (inductors and capacitors) in the power circuit.
The potential benefits of integrated power electronics will be robustness to shading, mis-
match, ageing, cell damage, flexibility of placement, fault tolerance, and ease of installation.

16.4 Configurations of Grid-Tied PV Systems

After selecting the correct voltage and power levels for an application in a PV system, MPPT
control can be done on string (array), module or cell levels. however, it is always desirable
to consider localized control as it can improve energy extraction by compensating shad-
ing, cell mismatch, and aging. In Fig. 16.10, four fundamental PV inverter systems suited
for MPPT in residential installations are given.
The configuration shown in Fig. 16.10A is the most common inverter system installed
in the residential settings. The string inverter in this topology generates the grid-level DC
voltages required by connecting PV modules in series, and it is inverted to AC by a centrally