The disclosure relates to technology for providing power, voltage, and/or current from a combination of DC sources. The DC sources may be photovoltaic panels. One aspect includes a stack of DC power sources (e.g., photovoltaic modules) with a DC to DC converter (e.g., power optimizer) associated with each DC power source. An output capacitor of a DC to DC converter is connected in series with its DC power source. Thus, there is a string of DC power sources and output capacitors connected in electrical series. The DC output of the system is a series connection of the DC power sources and the output capacitors. This reduces stress on the output capacitors, while allowing for efficient power generation by the DC power sources.