What? The entire premise was that it is cheaper at night. Thanks for jumping into the middle of the convo though and trying to jerk the wheel.
If household power purchase price doesnt change with time/generation cost, then there is not ability to act faster than the power company.
It may or may not make sense depending on your location. Many utilities would prefer to make customer-owned solar a very poor financial choice thru rate design (e.g. very high minimum charges, per-kw-installed solar charges, low daytime rates relative to evening rates, wholesale-rate compensation for exported production, etc). Some succeed.