Abstract: An electrical energy storage device comprises an electrical connection arranged to detachably connect to a power distribution system on a site; an energy store having an input arranged selectively to charge the energy store from the distribution system, and an output arranged selectively to discharge the energy store to the distribution system; a processor arranged to monitor at least one condition relating to the site, and to monitor at least one condition relating to the energy store, and to control the energy store to charge or to discharge dependent upon the monitored conditions; and preferably a communication interface for the processor. Such a device could be provided in a domestic site, in particular a site having a generation capacity such as PV panels, in order for the energy consumer at the site to obtain an electrical energy supply more efficiently or more cheaply, and in order to smooth out fluctuations in energy supply and/or demand from the site.

Abstract: An electrical energy storage device comprises an electrical connection arranged to detachably connect to a power distribution system on a site; an energy store having an input arranged selectively to charge the energy store from the distribution system, and an output arranged selectively to discharge the energy store to the distribution system; a processor arranged to monitor at least one condition relating to the site, and to monitor at least one condition relating to the energy store, and to control the energy store to charge or to discharge dependent upon the monitored conditions; and preferably a communication interface for the processor. Such a device could be provided in a domestic site, in particular a site having a generation capacity such as PV panels, in order for the energy consumer at the site to obtain an electrical energy supply more efficiently or more cheaply, and in order to smooth out fluctuations in energy supply and/or demand from the site.