Load matching of photovoltaic field orientation in stand-alone distributed power systems

The problem of optimizing the photovoltaic field orientation in stand-alone photovoltaic-hydrogen-powered distributed power systems (PHP-DPS) is treated in this paper. The system is supposed to be composed of a photovoltaic field, as energy source, and of a hydrogen energy backup subsystem including a hydrolyser, a hydrogen tank and a PEM fuel cell. Given the characteristics of the solar panels, of the switching converters and of the backup subsystem, three different load profiles have been considered with three typical irradiation diagrams corresponding to as many different typical days in a year. For each case study, the best photovoltaic field orientation, which involve the minimum number of panels to ensure the load power and energy requirements, has been found. Results of simulations allows to single the best configuration out, both whenever the system is supposed to work all the year round and if its operating period does not include winter. The paper puts in evidence that panels´ orientations chosen according to the load time profile allow to reduce the plant cost, in terms of number of panels and backup size, and to save some amount of energy that is not processed by the backup subsystem. To this regard, the paper also highlights that the best design of a stand-alone PHP-DPS maximizes the flux of energy that goes straight from source to load, as the energy production matches the load needs as much as possible. This objective is particularly important in PHP-DPS that are characterized by a low efficiency back-up path.