Maybe this idea isn't so small scale. To store 1 kWh would require five or six 200AH batteries, which would take up a fair bit of space and would also present some safety issues. Feeding that back into the grid might only net you a few cents. To make that a few dollars a day you'd need 600 batteries... and the payback time (profit covers capital) would be measured in decades. The batteries won't last that long.
I think there's a simpler way. Some providers offer smart meters which will separately count kWh in peak and off peak periods, getting one installed and making some small changes to the appliances you use could save you. Since my computers are on 24/7 even a relatively short off peak period (say midnight-6am) could provide a significant saving. One real world example I saw had the off peak rate at about 70% less than the peak rate.
Hmmmmmmm....
