Grid interconnection of renewable energy sources: Spanish legislation

The present production and use of energy are causing depletion of resources and serious environmental problems. Accordingly, more and more countries are examining a whole range of new policies and technology issues to make their energy futures “sustainable,” thus increasing governmental incentives for technology providers and utility mandates to incorporate significant levels of renewable resources. Hand-in-hand with the sustainable development initiative, in recent years the concept of a “Smart Grid” for the delivery of energy to consumers has emerged. Existing distribution networks were not designed to accept extensive distributed generation (DG). The actual paradigm may change in the near future impelled by a worldwide increasing of DG penetration in distribution grids. This paper presents the status and content of Spanish legislation on DG. Fundamental considerations are first discussed, exclusively regarding the grid-interconnection requirement. This paper also analyses the relationship between that guidelines and recognized international standard in a systematic way. Major requirement areas include general specifications, safety and protection strategies, and power quality requirements. This study reveals the diversity of requirements for DG grid connection coexisting, considering both the national and the international context; this stresses the urgent need for international harmonization. It is interesting to note that in Spain (as in most of the European countries), protections for LV photovoltaic systems are defined but not for the rest of the distributed generation technologies in low voltage. Thus, one could conclude from this study that probably the most important barriers are the lack of adequate requirements and procedures.