It isn't supposed to make sense
It's just trendy tat to sell to e-hipsters.
Battery storage is supposed to smooth out the spikes associated with PV and wind, but it is pretty inefficient. New batteries will only give you around 80% efficiency at optimal usage. Worse when the batteries get hot/cold/old or the load is not exectly matched.
Pump storage has been used for the same purpose for decades, has similar efficiency to new batteries and has a better ROI.
The scheme I am most familiar with is
http://en.wikipedia.org/wiki/Drakensberg_Pumped_Storage_Scheme. This has been operating now for 34 years with only relatively minor maintenance and has the added benefit of being able too use surplus electricity to pump water into a different watershed for agricultural use.
Biting the hand that feeds IT
