Interesting read, page-5

I have been working on a utility scale battery/inverter system, big enough to supply the whole of a small country town during network outages. My role is to design the the integration of the battery/inverter with the network from a protection and control perspective. Hence, yes, grid scale use of batteries is happening, but in Australia at least the uptake is not rapid at present due to the cost of battery/inverter systems. However, as the costs reduce, it is probable that grid scale battery/inverter systems will be used more widely.

No doubt domestic scale battery/inverter systems will experience rapid growth, and perhaps battery/inverter systems that can augment the supply to individual business customers will be popular, but I expect the uptake of grid scale battery/inverter systems will be slower.

In Europe it is a different scenario because Europe has a large quantity of unused wind energy. That is, during light electrical load periods there is an excess of wind powered electrical energy. Hence, if the excess energy can be stored during light load periods, and subsequently released during peak electrical load periods, the reliance upon fossil fuels and nuclear power will be diminished. However, at present the battery/inverter scale is insufficient to store the very large excess of wind powered electrical energy. Hence, the mainstream push at present is for hydrogen storage. That is, use the excess electrical energy to create hydrogen, then later use the hydrogen as an energy source to create electrical power during peak load periods. In addition, it is expected that the hydrogen can be mixed with natural gas, albeit at a low percentage, to increase the volume of gas available for use at the retail level. I attended a seminar regarding the hydrogen option a few months ago, and while the concept is sound, I have reservations as to whether it will be implemented on a large scale due to the inherent danger of hydrogen. Hence, while Tesla's 20 MW (80 MW.hr) proposal is small from a utility network perspective, it could lead to much bigger things.

Australian utilities are presently running trials for PV/battery/inverter systems as a replacement for a SWER supply, but due to the inconsistency of the sunlight, these trials also include a diesel generator. At present the cost of these systems is too large for individual farmers to foot the bill, but with the network utility avoiding network upgrade and maintenance costs, the trials could result in a modest uptake in remote areas. By the way, 1 MW.hr on a farm is not realistic, the trials are for units up to 20 kW.hr.