Optimisation of photovoltaic–diesel–battery stand-alone systems minimising system weight

Abstract

This article shows a new method for the optimisation of stand-alone (off-grid) hybrid systems (photovoltaic–diesel–battery) to supply the electricity of mobile systems such as non-governmental organization hospitals, temporary camps or other mobile facilities to be placed temporally in remote or conflictive areas. If there is difficult or dangerous access, the most important objective to be minimised is the total weight of the system. Also, the cost is an important variable to minimise. Nowadays, the majority of these systems are diesel-only or diesel-battery systems. However, depending on the duration of the temporary system, a photovoltaic–diesel–battery system can have a lower weight and/or cost. Three types of optimisation are considered: (i) minimisation of the weight of the system; (ii) minimisation of the cost; and (iii) minimisation of both weight and cost. The two first are conducted by genetic algorithms, and the last one is performed using multi-objective evolutionary algorithms. An example of application of this method to a temporary hospital in Central African Republic is shown, concluding that in the cases of more than 90days photovoltaic (flexible crystalline silicon panels)+diesel+battery is the solution which minimises weight. When minimising cost, all the cases include photovoltaic with high penetration.