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Multilevel inverters for photovoltaic energy systems in hybrid-renewable energy systems 95

Figure 5.14 Circuit diagram for the H5 method.

One of the pioneer companies in PV systems that proposed a solution to the issue
was SMA solar technology company who patented the method in 2005 [12]. Since
the leakage current from the inverter to PV panels is flown during zero state (when
the polarity generation part is in short circuit to apply zero to the output) this patent
inserts an extra switch (S5) to the PV panels that is disconnected during this time.
Therefore, there will be no path from the inverter to the PV panels during zero state
and the leakage current will be avoided. The circuit diagram of the method is illus-
trated in Fig. 5.14.
However, this method adds another switch in the current path that will add to the
power dissipation of the inverter. Therefore, in 2006 Sunways company proposed a
new method called highly efficiency and reliable inverter concept (HERIC) that over-
came the problem [13]. The general circuit diagram is depicted in Fig. 5.15.

Figure 5.15 Circuit diagram for HERIC method.