Grid Scale Energy Storage
Grid scale storage is energy storage that is directly connected to the grid, and whose output is ultimately managed by grid operators.
Grid scale storage constitutes large chunks of storage (typically MW or tens of MWs, sometimes hundreds of MWs), and aims at solving large scale problems in energy management and distribution.
Grid Edge Energy Storage
Grid edge storage is on the customer side of an electric meter, and, in general, aims at solving distribution issues for the customer whose meter it is.
In most cases, the customer is an industrial customer with significant energy consumption. However, with the recent spread of grid edge solar photovoltaic generation (6 of the top 10 builders in the US now offer solar PV options), residential customers are now starting to install local energy storage to store their solar PV energy.
Grid edge storage for industrial customers typically ranges in 10s to 100s of kWs, while storage for residential customers focuses in the kWs to the low tens of kWs.