Commercial storage system (non-residential ones), are becoming very popular thanks to the spread of lithium batteries. They are composed of a series of battery modules in one or more shelves, with the opportunity of having from few tens of kWh capacity up to some MWh, with tens of MW as power, according to the costumers’ needs.
Sometimes it is possible to fit these systems in containers, which are already cabled and ready to be used.
How they can be employed:
» optimize self consumption for activities with a PV plant;
» provide peak shaving functions, like reduction of peaks of energy taken by the network in order to reduce costs of electric supply;
» provide load shifting functions, meaning the reduction of energy taken by the network in specific moments;
» provide back up functions;
» optimization of systems with combustion generators;
» off-grid systems in network-isolated regions with the opportunity of managing the various energetic sources, form PV to wind power and hydroelectric;
» stabilize electric energy, by network operators.
In the market there are multiple available solutions and configurations with an “ad hoc” design, according to the many different demands, considering the installation location, the type of service, users’ consumption etc…
Since these systems are made up by a large number of batteries, the BMS functionality (Battery Management System) becomes essential. It is used to optimize discharge and balance the charging status of each single cell of the battery, ensuring security and protection functionalities. All this occurs keeping low energy consumption during standby.
The way in which cells are managed is very important to guarantee the forecasted performances and duration.
Design of the system
In addition to stored energy, also maximum power supplied by the system must be considered. This parameter influences the longevity of the entire system.
In many islands, diesel generators are staring to be substituted by PV systems combined with lithium storage systems.