Comment by mayama

To be specific, solar with 4hr storage is price competitive with grid right now. Storage becomes expensive after that at 8hrs even with projected sodium or lithium prices. For a datacenter usage they probably need couple of days storage at 50hrs like the planned google datacenter. Only alternate chemistry batteries that could be scaled up easily like flow, iron air, zinc etc. could be competitive for multi day storage, though most of these are still at experimental or pilot stages.