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The entry into force of Royal Decree-Law 1/2012 has led to the elimination of the support schemes to promote the use of the energy from renewable energy sources existing to date in Spain, and thus, certain standstill of this sector activity. In this context, some renewable technologies, mainly photovoltaic solar, can find in self-consumption an alternative for promoting their development and use. The self-consumption in the form of net-metering is mainly characterized by the possibility that the consumer can generate in situ part of the consumed electricity and use the network as storage or supply system. This option is still under study by the Government, so that there is a draft of Royal Decree that has not yet been approved. The aim of this paper is to analyze the economic viability of the net-metering mode in dwellings with small power photovoltaic facilities, considering those options that can contribute to make them viable.

This paper describes the confi guration, modelling and control of a new hybrid propulsion system for the Zaragoza tramway.The new tramway confi guration is composed by a Proton-Exchange- Membrane Fuel-Cell (PEM FC) as main energy source and a Li-ion battery and an Ultra-Capacitor (UC) as energy storage systems. Thus, the battery supports to the FC during the starting and absorbs the power generated by the regenerative braking. Otherwise, the UC, which is the element with the fastest dynamic response, acts mainly during power peaks which are beyond the operation range of the FC and battery. The FC, battery and UC provide with DC/DC converters which allow their connection to the DC bus and control the energy exchange. The new energy management system described is composed by three control loops in cascade for the FC converter and two control loops for the battery and UC. This control system has been evaluated for the real driving cycle of the tramway. The results show how the control system is valid for its application in this hybrid system.