Actually I think batteries will be the cheapest option for a very long time. They can be produced at a much higher scale than today (I wouldn't be surprised if

Actually I think batteries will be the cheapest option for a very long time. They can be produced at a much higher scale than today (I wouldn't be surprised if we see 10x the production in the next five to ten years and consequently prices below $30/kwh) and they can be setup incrementally. Most alternatives are fixed-size all-or-nothing affairs. Oh and the biggest downside of batteries, their low energy density doesn't really matter for stationary storage.