A review of energy storage technologies for large scale photovoltaic power plants

Energy storage can play an essential role in large scale photovoltaic power plants for complying with the current and future standards (grid codes) or for providing market oriented services. But not all the energy storage technologies are valid for all these services. So, this review article analyses the most suitable energy storage technologies that can be used to provide the different services in large scale photovoltaic power plants. For this purpose, this article first summarizes the different characteristics of the energy storage technologies. Then, it reviews the grid services large scale photovoltaic power plants must or can provide together with the energy storage requirements. With this information, together with the analysis of the energy storage technologies characteristics, a discussion of the most suitable technologies is performed. In addition, this review also discusses how to locate the energy storage within the photovoltaic power plant. The results show that (i) the current grid codes require high power - medium energy storage, being Li-Ion batteries the most suitable technology, (ii) for complying future grid code requirements high power - low energy - fast response storage will be required, where super capacitors can be the preferred option, (iii) other technologies such as Lead Acid and Nickel Cadmium batteries are adequate for supporting the black start services, (iv) flow batteries and Lithium Ion technology can be used for market oriented services and (v) the best location of the energy storage within the photovoltaic power plays an important role and depends on the service, but still little research has been performed in this field.