DIY battery for load-shifting ONLY

I have an enphase solar system already - solar only, no batteries. My electric utility has introduced a new plan where grid power is half-price from 11pm-5am. I want to look into the possibility of buying batteries to load-shift... charge for cheap at night, and then discharge during the day. I want this to be grid-tied and automatic. I do NOT need battery back-up for my home, and I'm not trying to go off-grid. This would be purely for load-shifting. I also don't need the capability for solar to charge the batteries... they would charge exclusively from the grid at night.

Can this be done DIY? Can someone point me in the right direction for components to buy? I want to figure out prices and then decide if it could pay for itself in utility savings. Thanks!