A power converter circuit comprising: a buck plus boost converter and a controller configured to peak power track one or more strings of solar cells coupled to inputs (914, 916) of the buck plus boost converter, and configured to operate the buck converter and the boost converter to set an input voltage and an input current at the inputs (914, 916) of the buck plus boost converter to a maximum power point of the one or more strings of solar cells, wherein the buck plus boost converter includes a buck converter followed by a boost converter with an inductor shared between the buck converter and boost converter, wherein the buck plus boost converter comprises a positive input lead, a negative input lead, a positive output lead and a negative output lead, that the buck converter comprises a first switch between said positive input lead and the buck side of the inductor and a second switch between said negative input lead and the buck side of the inductor, each switch having a parasitic body diode (926, 924), that the boost converter comprises a third switch between the boost side of the inductor and said negative output lead and a fourth switch between said positive output lead and the boost side of the inductor, each switch having a parasitic body diode (944, 946), and wherein the power converter further comprising a first current blocking element between the negative input lead and the buck side of the inductor, and a second current blocking element between the boost side of the inductor and the positive output lead, both coupled with a polarity such that a current may not backflow into the converter from the positive output lead and such that in the case of component failure a current path from the negative output lead through said first current blocking element, the inductor, said second current blocking element to the positive output lead is provided. a buck plus boost converter and a controller configured to peak power track one or more strings of solar cells coupled to inputs (914, 916) of the buck plus boost converter, and configured to operate the buck converter and the boost converter to set an input voltage and an input current at the inputs (914, 916) of the buck plus boost converter to a maximum power point of the one or more strings of solar cells, wherein the buck plus boost converter includes a buck converter followed by a boost converter with an inductor shared between the buck converter and boost converter, wherein the buck plus boost converter comprises a positive input lead, a negative input lead, a positive output lead and a negative output lead, that the buck converter comprises a first switch between said positive input lead and the buck side of the inductor and a second switch between said negative input lead and the buck side of the inductor, each switch having a parasitic body diode (926, 924), that the boost converter comprises a third switch between the boost side of the inductor and said negative output lead and a fourth switch between said positive output lead and the boost side of the inductor, each switch having a parasitic body diode (944, 946), and wherein the power converter further comprising a first current blocking element between the negative input lead and the buck side of the inductor, and a second current blocking element between the boost side of the inductor and the positive output lead, both coupled with a polarity such that a current may not backflow into the converter from the positive output lead and such that in the case of component failure a current path from the negative output lead through said first current blocking element, the inductor, said second current blocking element to the positive output lead is provided.