The Duck Curve Characteristic and Storage Requirements for Greening the Island of Porto Santo

One of the barriers to a higher dissemination of renewable generation is the mismatch that may exist between availability and energy consumption. Also, when the penetration of solar generation is very high, and due to the natural variation of that energy source some challenging situations may occur if demand varies in the opposite direction, leading to what is called "duck curve". In this situation, conventional generation may be no longer able to accommodate the ramp rate and range needed to fully utilize solar energy in power systems with considerable amount of solar generation. It was revealed that this could result in "overgeneration" leading to generation curtailment, with consequent decrease in benefits and wasted investment Storage and demand-side management are tools that may be used for dealing with that discrepancy between solar and wind generation and the demand, including facilitating the accommodation of higher solar electricity, and at the same time to allow a more efficient operation of the power system. This paper explores the duck chart in Porto Santo island, examining how much photovoltaic generation might need to be cut off if additional grid flexibility operations are not taken into account. It is shown that the solar penetration as low as 40% of annual energy could lead to marginal curtailment rates that exceed 30% of the solar generation. However, employing energy storage systems allow much greater penetration of solar resources, achieving a 50% renewable portfolio standard.