The present invention is directed to an apparatus and method for improving the power output of a solar energy system. A field level inverter controller is described that may improve the power output of individual solar energy systems in a field of solar energy systems by controlling the inverter voltage applied to strings of solar energy units in a solar energy system connected in parallel to an inverter. An inverter load voltage for an improved power output may be calculated or derived empirically. An algorithm stored in the controller may calculate an improved load voltage for the inverters based on factors such as string geometry, solar movement and shade patterns generated by surrounding structures. Improved power output may be empirically determined by the field level inverter controller when the inverter controller directs an inverter to sweep a range of voltage values until a maximum output is detected.
