No. The price differential isn't enough to offset the cost of the battery. If the battery cost fell by 75% it might be, but then you'd rapidly see off peak demand rise and peak demand shrink as everybody did this, the price difference would shrink and thus it would become uneconomic after you'd invested in the battery.
Also, because the standing charges of the network and central generation wouldn't change by much, the regulator would need to step in and institute the sort of complex charging that businesses are subject to, so you'd have a standing charge, a maximum capacity charge, a maximum actual current charge, and a unit charge, and thus the variable element of the bill would fall and the fixed element creep up (again undermining the price arbitrage).
The underlying financial case for local battery storage relies on beneficiaries benefiting at the the expense of other users. This isn't apparent at low levels of market penetration, but when a lot of people do it becomes a real problem. In much the same way that poor people in flats currently pay higher electricity prices to subsidise wealth pensioners getting PV or "renewable heat" subsidies.
Biting the hand that feeds IT
