Photovoltaic power converter systems and methods are described. In one example, a method for use in operating a solar power converter includes sampling a DC link voltage of a DC link during a first cycle of an alternating output voltage of a second stage at one instance when the alternating output voltage is crossing zero volts in a first direction. A voltage difference a voltage difference between the DC link voltage sampled during the first cycle and a DC link voltage sampled during a previous cycle when the alternating output voltage was crossing zero volts in the first direction is determined. A DC link power is estimated based at least in part on the determined voltage difference. The AC power output by the second stage in a second cycle is controlled based at least in part on the estimated DC link power.