I recommend you study the following paper. I have read it in detail for several times. Its data regarding Energy Storage Systems (ESS) would definitely be helpful for your research.
Regards,
Morteza Shabanzadeh
http://mortezash.blogfa.com/
Article Analysis of the Cost per Kilowatt Hour to Store Electricity
I just found a really cool link on the internet and since I had seen this question before I thought maybe you still need the information about actual installed energy storage facilities. You can select country, zoom in through the map and find the details such as technology uses, owner, contractor, manufacturer, funding sources, capital costs and many more. Here you go: