combination of solar photovoltaic cells from which the inverter 10 draws power the ac grid 20 represents the utility into which power is sourced by the inverter 10 a zero cross detector 22 provides a clock signal clk used to synchronize execution of an rms voltage calculation by an rms converter 24 anti islanding detection by the anti islanding controller 18 and execution of an mppt algorithm by the mppt system 14 a direct current dc to alternating current ac converter 26 operates to convert the dc output of the solar grid 16 to ac which is supplied to the ac grid 20 the mppt algorithm of the present invention is illustrated in greater detail in fig3 the mppt algorithm uses an improved form of the u201c perturb and observe u201d method that is implemented on a discrete time basis in particular the mppt algorithm makes a decision to increment step s 6 or decrement step s 7 the ac output current every n zero crossings of the ac grid voltage every n 2 cycles of the ac grid 20 where the zero crossings are determined by the zero cross detector 22 the power from the solar grid 16 power_sum is calculated between the last two zero crossings regardless of the output current update period n zero.