  Using Photovoltaic systems is gradually expanded by increasing energy demand.
Abundance and availability of this energy, has turned to one of the most
important sources of renewable energy. Unfortunately, photovoltaic systems have
two big problems: first, those have very low energy conversion efficiency (in
act between 12 and 42 percent under certain circumstances). Second, the power
produced by the solar cell depends on nonlinear conditions such as solar
radiation, temperature and charge feature. According to this, received power
maximum of photovoltaic cells depends on different non-linear variables, it is
necessary to be continuously traced, as maximum received power of the cell (by
controller). In this research, the increasing efficiency of photovoltaic
systems has been investigated by using Maximum Power Point Tracking (MPPT) in
two different modes contained connected to the Grid and disconnected from the
grid with simulation by MATLAB software. The obtained results showed that the
proposed technique is able to improve the current, voltage and power output of
photovoltaic cells.
